Consciousness and Cognition 18 (2009) 628–638

Contents lists available at ScienceDirect

Consciousness and Cognition

journal homepage: www.elsevier .com/locate /concog

In what sense ‘familiar’? Examining experiential differenceswithin pathologies of facial recognition

Garry Young *

Division of Psychology, Nottingham Trent University, Nottingham, UK

a r t i c l e i n f o

Article history:Received 2 March 2009Available online 22 July 2009

Keywords:ProsopagnosiaCapgras delusionFacial recognition pathologyOvert and covert routesSense of familiarityFamiliarity of beingSCR measure

1053-8100/$ - see front matter � 2009 Elsevier Incdoi:10.1016/j.concog.2009.06.006

* Corresponding address: Division of Psychology,

1 Capgras delusion: the belief that relatives and/oLachaux, 1923). In addition, although it was Bauer (1Capgras delusion.

2 According to Schweinberger and Burton (2003)respectively.

3 PINs contain semantic information for the identifialso provide an entry point into associative memoryperson’s favourite football team, or where we first m1986).

a b s t r a c t

Explanations of Capgras delusion and prosopagnosia typically incorporate a dual-routeapproach to facial recognition in which a deficit in overt or covert processing in one con-dition is mirror-reversed in the other. Despite this double dissociation, experiences ofeither patient-group are often reported in the same way – as lacking a sense of familiaritytoward familiar faces. In this paper, deficits in the facial processing of these patients arecompared to other facial recognition pathologies, and their experiential characteristicsmapped onto the dual-route model in order to provide a less ambiguous link betweenfacial processing and experiential content. The paper concludes that the experiential statesof Capgras delusion, prosopagnosia, and related facial pathologies are quite distinct, andthat this descriptive distinctiveness finds explanatory equivalence at the level of anatom-ical and functional disruption within the face recognition system. The role of skin conduc-tance response (SCR) as a measure of ‘familiarity’ is also clarified.

� 2009 Elsevier Inc. All rights reserved.

1. Introduction

Since its inception in 1990, Ellis and Young’s ‘dual-route’ model of overt and covert facial recognition has formed the basisfor a number of explanations of prosopagnosia and the Capgras delusion1 (see Bayne & Pacherie, 2005; Bortolotti, 2005; Colt-heart, 2007; Davies & Coltheart, 2000; Gilleen & David, 2005; Klee, 2004; Stone & Young, 1997; Young & de Pauw, 2002; Young,2008a). The function of the overt route matches closely Bruce and Young’s (1986) original sequential system in which facialcharacteristics are first encoded and then processed by the Face Recognition Unit (FRU), before activating Person Identity Nodes(PINs) (in the case of familiar faces).2 Activation of a particular PIN enables contextual semantic and biographical informationrelating to that face (person) to be accessed, including as a final step the person’s name.3 Ellis and Young contribution to thisprocess was to include a second, covert and parallel pathway which subserves our affective response to familiar faces. In morerecent versions, however (see Breen, Caine, & Coltheart, 2000; Ellis & Lewis, 2001), the covert route forms part of a dual system

. All rights reserved.

School of Social Sciences, Nottingham Trent University, Burton Street, Nottingham, NG1 4BU, UK.

r significant others have been replaced by an impostor (originally documented by Capgras & Reboul-984) who originally proposed the dual-route model, it was Ellis and Young who adopted it to explain the

, the anatomical location for the FRU and PINs is the fusiform gyrus and anterior temporal region,

cation of individuals, such as occupation or the context in which we typically encounter them. But they, where more general or peripheral, or even episodic information, may be accessed – for example, theet (at a football match), which may link to more general football related information (Bruce & Young,

G. Young / Consciousness and Cognition 18 (2009) 628–638 629

of processing post FRU.4 In other words, faces are processed along a single route until they reach the FRU. After that, familiarfaces which are matched to a stored representation by the FRU not only activate PINs but also produce heightened autonomicarousal, an indices of which is increased skin conductance response (SCR).5

The connection between SCR and the facial recognition pathologies of prosopagnosia and the Capgras delusion6 has beenmuch discussed. It is well documented, for example, that prosopagnosic patients typically show an increase in SCR when pre-sented with images of familiar faces despite a failure to identify the face as belonging to someone they know (Bauer, 1984; Tra-nel & Damasio, 1985). Similarly, research has shown that Capgras patients do not show heightened SCR when presented with afamiliar face (Ellis, Young, Quayle, & de Pauw, 1997; Hirstein & Ramachandran, 1997; Brighetti, Bonifacci, Borlimi, & Ottaviani,2007). What is less extensively discussed, however, is the relationship between SCR and the experiences of these patient-groups.Ellis and Young claim that SCR is a measure of covert recognition – present in prosopagnosia and absent in the Capgras delusion.But what is less clear – and certainly less coherently described – is the manner in which this presence or absence of covert rec-ognition manifests itself within the patient’s experiential content.

The aim of this paper is to examine the relationship between SCR and experience more closely; not only by comparingsimilarities and differences in the experiential, anatomical and functional states and processes of prosopagnosic and Capgraspatients, but also by presenting other case study examples of facial recognition pathologies, as well as research findings fromwork within the recognition without identification (RWI) paradigm. Together, these comparisons will help us understand,with a greater degree of clarity and coherence, what these experiences entail and how they can best be explained with ref-erence to functional deficits within the most recent dual-route model (that of Ellis & Lewis, 2001). The paper also aims todisambiguate what it is that the SCR is a measure of in cases of prosopagnosia and the Capgras delusion.

Before discussing these issues further, however, some preliminary groundwork must be done. In the next section, I willmap the anatomical and functional structure of the dual-route model, and introduce the double dissociation characteristic ofEllis and Young’s original mirror-image account of prosopagnosia and the Capgras delusion (which is maintained by Ellis &Lewis). The material presented in this section is well documented and much discussed; but as it forms the basis for the argu-ments to follow, it is important to present of overview – however rudimentary – of our understanding to date. In addition, asthe focus of this paper is on patient experience, particularly phenomenal content, it is important to clarify how the terms‘experience’ and, ‘phenomenal experience’ are being used. Put simply, experience should be understood as synonymous withconsciousness. When a person experiences x, he/she is conscious of x. Phenomenal experience concerns the what-it-is-like-ness (Nagel, 1974) of experiencing x – in other words, the manner in which x pervades consciousness, the nature of itssalience.

2. The anatomical and functional basis for a double dissociation

Put simply, the prosopagnosic patient’s inability to consciously recognise (as in, identify) familiar faces7 is believed tostem from damage to the ventral route of the visual system subserving conscious visual recognition. Yet when presented witha familiar face, despite a failure to experience any conscious recognition of that face, prosopagnosic patients nevertheless ex-hibit an increase in SCR (see Bauer, 1984; Tranel & Damasio, 1985).8 This is often reported as a measure of unconscious or covertrecognition, said to be caused by the intact ventral-limbic structure projecting to the amygdala. In the case of the Capgras pa-tient, damage to these two structures is ‘mirror-reversed’ (Ellis & Young, 1990), such that the ventral route is functional but notthe connecting ventral-limbic structure (see Breen et al., 2000, for a more detailed discussion on this, and also Haxby, Hoffman,& Gobbini, 2000; 2001).9 As such, when presented with a familiar face, Capgras patients demonstrate no increase in SCR. In-stead, they exhibit what Fine, Craigie, and Gold (2005) refer to as emotional hyporesponsiveness; (see also Ellis et al., 1997; Hir-stein & Ramachandran, 1997; Brighetti et al., 2007).10 The absence of increased SCR when in the presence of a familiar person,along with their still intact ability to overtly recognise who the person is meant to be11 (despite their belief to the contrary) is

4 For an alternative view, see de Haan, Bauer, and Greve (1992).5 Skin conductance response (SCR) is often identified in the literature as galvanic skin response (GSR). However, SCR will be used throughout this paper. In

addition, an alternative electrophysiological indicator of covert recognition is ERP (event-related potential) – see Renault et al., 1989 and Bobes et al., 2003.6 I am not claiming here that Capgras delusion is just a pathology of facial recognition. I acknowledge that there is an additional delusional element to the

condition. However, the focus of this paper is on the underlying phenomenology only.7 The type of prosopagnosia discussed throughout this paper is associative, in which faces are recognised as faces, and even gender identified. I will not be

discussing apperceptive prosopagnosia, characterised by the inability to recognise a face as a face.8 Stormark (2004) even measured increased SCR in preschool children (26–48 months) when presented with faces of former playmates compared to

unfamiliar faces, despite a lack of overt recognition.9 Originally, conscious recognition was believed to involve the ventral route which projects from the primary visual cortex to the inferotemporal cortex (see

Bauer, 1984). Conversely, in the case of Capgras delusion, the underlying aetiology of delusional beliefs — the anomalous phenomenal experience — wasbelieved to stem from damage to the dorsal route which projects, again, from the primary visual cortex, only this time to the posterior parietal cortex. Breenet al. (2000), however, suggest that covert recognition is subserved, not by the dorsal route (which they argue plays no part in visual recognition), but bypathways that connect the ventral stream to the limbic system (ventral limbic structure) and, in particular, the amygdala. (I shall adopt Breen et al.’s revisionhere.)

10 The earlier studies by Ellis et al. and Hirstein and Ramachandran used famous faces rather than faces of the patient’s family and friends. This discrepancywas corrected by Brighetti et al. who found the same reduced SCR during the presentation of personally familiar faces.

11 Young (1999) notes that there have been reports of Capgras patients who claim to perceive differences in the ‘impostor’. However, when pressed on whatexactly these differences are, they have difficulty pointing them out.

630 G. Young / Consciousness and Cognition 18 (2009) 628–638

said to produce within the Capgras patient an anomalous experience – a ‘bizarre’ underlying phenomenology signifying thatsomething is wrong/not quite right.

The dual-routes approach to facial recognition, especially the proposed function of the covert (affective) pathway and theextent to which SCR is a measure of this function, has created a degree of ambiguity within explanatory and descriptive ac-counts of prosopagnosia and the Capgras delusion. This ambiguity has been previously noted. Breen et al. (2000), for exam-ple, comment on the fact that SCR is simply ‘‘a non-specific physiological response that occurs when a subject is aroused insome way” (p. 57). As such, how one interprets its increase – particularly as a measure of cognitive function or (I am arguing)phenomenology – is ‘‘far from obvious” (p. 57). Likewise, Hohwy (2004) notes that, in the context of the Capgras delusion,reduced SCR ‘‘does not explain the character of the subjective experience” (p. 66). After all, one does not have a ‘reduced SCRexperience’.

To date, the connection between the SCR of either patient-group and the phenomenal character of their experience is, atbest, ambiguous; and, as I have detailed below, typically reported in a manner that closer inspection reveals to be somewhatpuzzling. Stone and Valentine (2003), for example, attest to the fact that the prosopagnosic patient has an inability to gain asense of familiarity from a known face. Ellis and Young (1990) likewise maintain that, to the prosopagnosic patient, ‘‘faceslook normal enough but evoke no sense of familiarity” (p. 240). A similar view is endorsed by Brédart and Young (2004)who assert that, with prosopagnosia, ‘‘there is no sense of overt recognition that this face is that of a familiar person” (p.184). Yet Phillips (2002), notes a similar experience in the case of Capgras delusion, stating that the patient ‘‘may recognisethe face without the tone of familiarity” (p. 61). Gerrans (1999), for his part, adds: the Capgras delusion involves ‘‘a form ofneurological deficit which damages a discrete capacity to generate feelings of familiarity” (p. 596). Finally, Ellis and Lewis(2001) describe the Capgras delusion as involving, in part, a ‘‘failure to receive a confirmatory feeling of familiarity”. (My ital-ics in all quotations.)12

In each of these examples, the descriptions are consistent irrespective of pathology. Moreover, I am confident that even acursory glance through the voluminous literature on prosopagnosia and the Capgras delusion will confirm that they are alsorepresentative of the consensus view – that the phenomenal characteristic of both conditions is typically described as a lackof a sense familiarity toward familiar faces (persons). Now, in itself, this hardly constitutes a major anomaly or puzzle. Rather,the puzzle arises when one considers that, with the Capgras delusion, a lack of a sense of familiarity is said to result fromdamage to the covert pathway of the face recognition system, whereas, in propsopagnosia, the exact same experience is saidto stem from damage to the overt pathway. Thus, when matching the phenomenal description of each condition to the cor-responding functional disruption, a disparity occurs. One is therefore left to puzzle over why it is that, in the absence of afunctioning covert pathway, the Capgras patient lacks a sense of familiarity, but in a system in which this function is intact(prosopagnosia) the patient fails to experience a corresponding sense of familiarity. In short, why is it that in the presence of‘mirror-reversed’ disruption (as posited by the mirror-image model), each patient-group incurs the same, rather than theopposite, experiential state of familiarity?

It could be, of course, that the term ‘‘a sense of familiarity” is simply referring to something different in each condition – adifferent sort of familiarity. Thus, the sense of familiarity characteristically absent from the prosopagnosic patient’s experi-ence is that associated with physical recognition. For the prosopagnosic patient, there is nothing-it-is-like to distinguishfamiliar from unfamiliar faces (qua identifiable from unidentifiable) based on physical appearance. The absence of a senseof familiarity in this context is simply an experience which corresponds to the inability to identify, and therefore distinguishbetween, those faces which are known from those which are not. (Interestingly, some prosopagnosic patients can broadlydistinguish ‘famous’ from ‘unknown’ faces – a point we shall return to in Section 5.) Conversely, the sense of familiarity ab-sent from the Capgras patient’s experience is not the something-it-is-likeness of physical recognition – that is, identificationbased on the person’s physical features – rather, it is an experience that would seem to equate to an inability to recognisesomeone as being the person they claim to be. Capgras patients, then, fail to experience some form of familiarity of being – anexperiential state of connectedness with the other person – that is independent of physical recognition (see Section 6).

If such experiential differences are possible then a number of questions arise:

(i) If an experience of familiarity of being is independent of physical recognition, then what must it be like to have thissense of familiarity in the absence of physical recognition?

(ii) Conversely, what must it be like to physically recognise x without experiencing familiarity of being toward x, as seemsto be the case with the Capgras delusion?

(iii) If a failure to experience familiarity of being toward x is related to disruption in the covert pathway, then why does theprosopagnosic patient (whose covert pathway is intact) not experience familiarity of being independent of (that is, inthe absence of) physical recognition? Why is the prosopagnosic patient unable to distinguish between faces towardwhich he experiences familiarity of being, and those toward which he does not, despite having a pathological inabilityto identify (as in, physically recognise) one face from another?

A closer examination of the dual-route model of face recognition will, I contend, shed some light on these questions; andin conjunction with discussion on other related pathologies and the findings of recognition studies help clarify the experi-

12 See Young (2007a) for a more detailed discussion on this issue.

G. Young / Consciousness and Cognition 18 (2009) 628–638 631

ences of prosopagnosic and Capgras patients. In the next two sections I will address questions (i) and (iii), paying particularattention to what is involved in experiencing a sense of familiarity toward someone in the absence of identification. Afterthat, I will go on to discuss why this sense or experience of familiarity – this familiarity of being (I will use these terms inter-changeably) – is not experientially salient in prosopagnosia.

3. What is it to have a sense of familiarity without identification?

Experientially, there is clearly a difference between being in a room full of people I am acquainted with and the sense offamiliarity identified by Cleary and Specker (2007) as tartling13 – to sense that a face is familiar without being able to retrieveassociated information, such as the person’s name or other relevant semantic or biographical details.14 Thus, Lyon (1996) con-cludes, the familiarity of tartling will only strike one if it is unexpected” (p. 89). Whether something is expected (or not) is oftendictated by context, as is well illustrated by the butcher-on-the-bus example (Mandler, 1980). Encountering the butcher out ofcontext (on the bus) means that those additional identity cues, more typically associated with his shop (the place I expect to seehim), are unavailable. On the bus, I experience the salience of tartling; I am struck by a sense of familiarity in a way that I am notwhen presented with the butcher in his more usual surroundings. So how might we distinguish the familiarity of the butcher-in-the-shop from the tartling of the butcher-on-the-bus? As already noted, context is an important antecedent; but a more sub-tle relationship, is that between an item looking familiar and feeling familiar. As Lyon states:

There is. . . a distinctive experience of familiarity of appearance, of looking familiar, which is arguably common to most, ifnot all, instances of the experience of a perceived person seeming familiar. (1996, p. 89).

For Lyon, familiarity of appearance is synonymous with the ‘‘nature of the sensory perception” (p. 89). This, I suggest,equates to FRU processing. Importantly, this does not mean that items that are familiar or unfamiliar in appearance haveintrinsically different sensory natures; rather, its means that their ‘‘manner of achievement is noticeably different” (p. 93; ital-ics in original). By ‘manner of achievement’, Lyon means ease and speed of processing. (In the discussion to come, this will belinked to ease and speed of processing from FRU to PINs.) Thus, for a face to appear more familiar to me is simply for it to beprocessed in less time and with less cognitive effort (including the allocation of fewer attentional resources) than if it wereunfamiliar. There is, however, a caveat to Lyon’s comments: ease and speed of processing may distinguish a familiar facefrom an unfamiliar one when (as a result of the ease and speed of processing) identification is achieved; but a failure of iden-tification may still result in a pervasive sense of familiarity – tartling. Does processing fluency play a role in the experience oftartling? If so, are different senses of familiarity mediated solely by differences in processing fluency?

Like Lyon, Jacoby and colleagues claim that experiential states of familiarity are mediated by processing fluency (see Ja-coby & Dallas, 1981; Johnston, Dark, & Jacoby, 1985; Jacoby & Whitehouse, 1989; Kelly & Jacoby, 1990). However, Morris,Cleary, and Still (2008) provide evidence to suggest that it is not perceptual fluency per se but, rather, the physiological arousalassociated with perceptual processing that is more directly responsible for feelings of familiarity. As they note:

[T]he feeling of familiarity is not a direct result of activation of memory representations, nor is it an attribution based onprocessing fluency. Instead, the feeling of familiarity stems from one’s awareness of the autonomic arousal associatedwith the allocation of resources toward recollection. (p. 1379)

In particular, Morris et al. are interested in tartling (what they call recognition without identification); the expression ofwhich they claim can be linked to an increase in autonomic arousal as measured by SCR. They also share the view notedearlier that the interpretation of SCR – that is, what it is judged to be a measure of – can be ambiguous. SCR can be influencedby novelty and familiarity (amongst other things), depending on the nature of the task, and therefore requires context to helpdisambiguate what it is it is meant to be an indicator of.15 As Morris et al. explain: if a task involves identification (having tostate what is it that you see) then SCR may increase in response to the presentation of a novel rather than familiar item (assuccessful identification of the former may require the allocation of additional cognitive resources). In contrast, if the task in-volves recognition (having to state whether the item had been presented previously, rather than what it is) then a familiar (pre-viously presented item) may produce increased arousal, and with it increased SCR.

To test the claim that increased arousal corresponds to an increase in the allocation of cognitive resources, and that this,in turn, produces a sense of familiarity, Morris et al. devised a study based on the recognition without identification (RWI)paradigm (Cleary & Greene, 2000; Peynircioglu, 1990). Participants were asked to identify words from a rapidly presentedlist, some of which had been previously studied (each word was presented for 30 ms so as to hinder identification).16 As well

13 The word ‘tartling’, we are told by Cleary and Specker, has its roots in the Scottish language.14 Yovel and Paller (2004) noted that when participants experienced familiarity without identification, the magnitude of neural response (ERP) was reduced

and occurred for a shorter duration, suggesting an absence of the type of context/biographical retrieval processing characteristic of identification (see also Groh-Bordin, Zimmer, & Ecker, 2006.

15 Denburg, Jones, and Tranel (2009), for example, measured an increase in SCR in a patient suffering from simultanagnosia. The increase corresponded to thepresentation of negatively-charged stimuli (e.g. an image of a burned and bloodied body), despite the patient being unable to consciously identify what theimage was. In this context, the large amplitude SCR was interpreted as the covert recognition of the (negative) affective valance of the image.

16 In the original study, there were in fact two separation conditions for word presentation – one at 30 ms (as noted here), the other at a slightly longerduration of 50 ms. However, the reason for this difference in presentation times need not concern us here.

632 G. Young / Consciousness and Cognition 18 (2009) 628–638

as trying to identify the words, participants were also required to rate each word on the likelihood that it had been previouslystudied (using a scale of 0–10). The study was designed to distinguish between autonomic arousal associated with identificationand autonomic arousal associated with recognition. Morris et al. reasoned that there should be at least a minimal level identi-fication preceding recognition. Therefore, autonomic arousal associated with identification (short-latency SCR;<1.75 s) shouldprecede any autonomic arousal associated with recognition (long-latency SCR; > 1.75 s): adding, the longer-latency effect, alone,should correspond to a feeling of familiarity.

Two of the study findings are of particular interest to this paper. First, words given a higher recognition rating (a higherlikelihood of been previously studied) were associated with longer-latency SCRs irrespective of whether they had in factbeen previously studied (the converse occurring in the case of those associated with shorter-latency SCRs). Second, theauthors note that whether the word was correctly identified or not did not affect recognition rating in cases of longer-latencySCR. From this, it was concluded that the longer-latency effect is not a result of successful recollection (identification) but,rather, ‘‘more consistent with [the] proposal that longer-latency SCRs reflect the allocation of resources toward recollection”(p. 1382; italics in original). Morris et al. also report similar results when testing participants on their rating of faces ratherthan words.17 From this they concluded that it is appropriate to refer to familiarity as a feeling which stems from the ‘‘auto-matic arousal that accompanies the allocation of processing resources in support of recollection” (p. 1384), rather than process-ing fluency per se.

What we can take from this study, certainly in response to question (i) (What must it be like to have a sense of familiarityin the absence of physical recognition?), is that to experience familiarity in the absence of identification is to experience tar-tling. But, moreover, the study also indicates that it is not the presence of SCRs per se that correspond to tartling; rather, it isSCR latency length: for in cases of short-latency SCRs, the corresponding sense of familiarity was low (based on ratings, atleast). Might this difference in SCR offer some insight into question (iii)? (Why do patients with prosopagnosia, despite hav-ing intact covert pathways (and showing increased SCR), fail to experience familiarity of being toward familiar faces?) If it isnot the presence of increased SCR per se that is important but latency length (because this is a measure of increased auto-nomic arousal brought on by resource allocation), then this would seem to match what we know about prosopagnosia – thatthere exists a deficit in identification. It seems reasonable to conjecture that this deficit stems from a dysfunction in resourceallocation.

Unfortunately, research reporting increases in SCR – whether in prosopagnosic patients, other related pathologies, or evenin ‘normal’ samples – does not indicate SCR latency length (as Morris et al. have done). Ellis and Lewis (2001) note, for exam-ple, that a peak SCR occurs somewhere between 1 and 5 s after exposure to the face. Consequently, it is difficult to comparedirectly, Morris et al.’s findings with those reporting SCRs based solely on amplitude. However, whilst acknowledging this,one might still speculate thus: if long-latency SCR is a measure of the autonomic arousal produced by resource allocation (inrecognition tasks) which pervades consciousness as a familiarity of being, and as prosopagnosic patients do not experiencefamiliarity of being, then what might their increased SCR (toward familiar faces) be a measure of, and in what form, if any,does it pervade consciousness?

A study by Greve and Bauer (1990) should prove useful in answering this question. Greve and Bauer presented a prosop-agnosic patient with pairs of unknown faces, although on each occasion one of the pair had been studied by the patient ear-lier. When asked to select the previously studied face accuracy was 53%: not significantly above chance (as one might expectfor someone with prosopagnosia). However, when asked to select the preferred face, the face that had been studied previ-ously was selected 70% of the time, significantly above chance. Thus, when instructed to state a preference, as this taskdid not require a sense of recognition (after all, it is possible to state which of two unrecognised faces one prefers), a signif-icant match occurred between prior exposure and preference. This raises the question: why did the prosopagnosic patientprefer previously seen but consciously unrecognised faces?

Stone and Valentine (2003) explain this in terms of the exposure effect (see Zajonc (2001) for a review) in which preferencefor a stimulus increases simply as a result of one’s repeated exposure to it. Changes in affect therefore depend upon a par-ticipant’s objective history of exposure and not on his ability to consciously recognise the object (Zajonc, 1980, 2000); somuch so that the exposure effect increases even when conscious recognition is not possible. This is certainly compatible withthe prospopagnosic patient’s demonstration of increased SCR when in the presence of familiar (based on increased exposureto) faces. But, importantly, and in relation to question (iii) (Why does the prosopagnosic patient not experience some form offamiliarity of being independent of physical recognition?), the positive affect does not manifest itself as conscious recognition,or as an feeling of familiarity of being from which one can infer recognition. Instead, it is said to produce a general (or diffuse)positive affect state (Zajonc, 2001) which, I am suggesting here, pervades consciousness as a feeling of preference, at least inthe context of a forced-choice preference task.

Continuing with question (iii), in the next section I will draw a comparison between prosopagnosia and other pathologiesof facial recognition, in the hope that such a comparison with offer further insight into why the prosopagnosic patient fails toexperience familiarity of being when in the presence of a familiar person.

17 Cleary and Specker (2007) likewise presented a series of faces to participants and asked them to judge which had been presented previously using twotypes of item-based recognition. They found that participants recognised previously studied items either by directly recalling that the face had been previouslystudied (recognition through direct recall), or ‘‘on the basis of a sense of familiarity with the test item” (p. 1610) – the stronger the sense of familiarity, thehigher the rating given. Previously studied items tended to be rated as more familiar than unstudied items, even when neither could be directly recalled ashaving been studied or not.

G. Young / Consciousness and Cognition 18 (2009) 628–638 633

4. Feelings of familiarity in related pathologies

In the RWI task, Morris et al.’s participants were not, of course, prosopagnosic; yet, because of speed of presentation(30 ms), they were not always successful at identifying the item. In terms of individual items, familiarity did not correspondto successful identity, but latency. One might speculate, then, that the allocation of resources (of which the longer-latencySCR is said to be a measure) was triggered by some feature of the item: a feature that was able to initiate the allocation ofresources toward the goal of identification without necessarily (in all cases) achieving that goal. Support for this suggestioncan be found, I contend, in cases of false recognition based on right hemisphere damage (in the absence of prosopagnosia).

Rapcsak and colleagues discuss patients with right hemisphere lesions whose face processing impairment is such that itcreates a ‘‘false. . . sense of familiarity with an unfamiliar face” (1994, p. 574; see also Rapcsak, Polster, Glisky, & Comer,1996). They also describe how the structural encoding of facial information is anatomically and functionally independent.The left hemisphere is responsible for the processing of local or component facial features (such as the nose or mouth),whereas the right hemisphere processes these items together in the form of a global or configurational feature (see also Ta-naka & Farah, 1993; Rossion et al., 2000; Barton, 2008). In patients WJ and BH, severe right hemisphere infarctions resultedin an inability to process global facial information. However, each patient’s intact left hemisphere allowed the encoding oflocal features. The disruption in their facial processing manifest itself as a tendency to misrecognise unfamiliar faces asfamiliar. Rapcsak, Polster, Comer, and Rubens (1994) suggest that the processing of local features in the absence of any formof global constraint results in the activation of the FRU. Activation of the FRU subsequently triggers activity in the PINs whichact to retrieve specific person-identity information from memory. Failure to successfully identify the face (owing to the lackof global facial processing) produces an unspecified sense of familiarity.18 Based on the findings of Morris et al., I would arguethat the sense of familiarity is a product of the increase in autonomic activity brought about by the allocation of resources to-ward the retrieval of additional specific person-identity information, triggered incorrectly by the encoding of local (only) facialfeatures.

A similar demonstration of inappropriate feelings of familiarity was reported by Vuilleumier, Mohr, Valenza, Wetzel, andLandis (2003), but in relation to contrasting neurological impairment. Vuilleumier et al. describe a case of hyperfamiliarity ina patient (JR) who experienced an ‘‘abnormal feeling of familiarity” (p. 903) toward strangers. JR presented with damage tothe left hemisphere (the lateral temporo-occipital junction). As well as having a strong sense of familiarity toward unfamiliarpeople, JR was impaired at processing local facial features (the opposite of that shown by Rapcsak et al.’s patients). Vuilleu-mier et al. suggest that her hyperfamiliarity was in part a result of her ability to process faces based on their global features(a product of right hemisphere function). In the absence of specific and disconfirmatory encoding of local facial features, Iconjecture that the processing of global features is sufficient to activate the FRU. In the absence of more specific person-iden-tity information (owing to a failure on the part of her PINs to retrieve such information, because there is none to retrieve), butas a result of the increase in autonomic activity that stems from the allocation of resources to this task, a pervasive sense offamiliarity ensues.

Anecdotal evidence from JR herself is suggestive of this increase in cognitive processing. She states that on those occa-sions when she truly recognised someone, it was ‘‘more automatic, more natural” (p. 893). Appropriate recognition wastherefore more ‘‘confident and associated with immediate retrieval of a specific identity” (p. 893). JR’s experience whenin the presence of familiar people suggests processing fluency. Despite not being able to encode the specific, local featuresof a face, the global features of the familiar face are nevertheless sufficient to allow a match to be found (where one is to befound) through the activation of a corresponding PIN (via the FRU). On the occasion of a familiar person being present, iden-tification requires the allocation of fewer resources to the task. Experientially, this can be contrasted with those occasionswhen a stranger is present and a false sense of familiarity pervades consciousness: something akin to tartling, I suggest.

As a final example, Rapcsak, Reminger, Glisky, Kaszniak, and Comer (1999) describe patients (JS and BW) who, as a resultof frontal lobe damage, engage in false recognition of unfamiliar faces owing to their inability to attribute the ‘‘experience offamiliarity to its appropriate source” (p. 285; see also Rapcsak, Nielsen, & Littrell, 2001; Verstichel, 2005). As Rapcsak et al.explain:

[F]rontal lobe participation becomes critical under conditions of uncertainty when the face cue does not directly elicitrelevant contextual information, leaving the source of familiarity unspecified. (1999, p. 286)

Right prefrontal damage results in a failure of the frontal executive system to suppress false recognition. By monitoringactivity in the system responsible for facial recognition (particularly the FRU and PINs), the central executive is able to make‘executive’ decisions regarding the appropriateness of this activity. If the FRU is activated and, because of a failure to retrievespecific person-identity information immediately, there is an increase in resource allocation and subsequent autonomicarousal, then the result is (as I have argued) an experience of tartling. On such an occasion, according to Rapcsak et al.,the ‘‘frontal executive system must initiate a strategic memory search in order to reinstate the appropriate context forthe feeling of familiarity evoked by the face” (1999, p. 286).19 If, after the strategic search, no specific context and person-iden-tity information is produced, then this should result in the suppression of the sense of familiarity. Of course, when processing is

18 Rapcsak et al. do report that, on occasion, a patient may mistakenly identify an unfamiliar face based on a single local feature – they may claim that theforehead or eyes (or whatever) look familiar, stating ‘‘ah, it’s such and such. . . from such a place”.

19 For more recent research and discussion on this, see Pannu, Kaszniak, and Rapcsak (2005).

634 G. Young / Consciousness and Cognition 18 (2009) 628–638

fluent and identity retrieval immediate, the executive system need not be activated (as is the case most of the time). As notedearlier, typically, we are not constantly struck by a sense of familiarity when wandering around a room full of friends. Undersuch circumstances, there is no increase in processing, no increase in arousal, and no need to initiate a strategic memory search.However, in cases of right prefrontal lobe damage, there is a general failure to activate the executive system, and therefore afailure to suppress tartling. Consequently, when presented with an image that is, say, similar to a familiar face, or perhapsslightly distorted, instead of the patient concluding that despite the initial sense of familiarity the face is in fact unknown,he mistakenly judges it to be someone he knows.20

In experimental studies measuring the RWI effect, or pathological case study reports of misrecognition or hyperfamiliar-ity, individuals make recognition judgements based on a salient sense of familiarity.21 What I have argued, thus far, is that thissense of familiarity stems from an increase in autonomic arousal that, itself, is the product of increased resource allocation with-in the face recognition system. It is the increase in autonomic arousal that pervades consciousness as a sense of familiarity, ortartling; and it is this increase in autonomic arousal that contributes to an elevated SCR. But as noted earlier, our interpretationof what the SCR is a measure of is largely dependent on the differentiating features of the task – whether the participant is re-quired to identify novel stimuli or recognise familiar (as in, previously studied) items, for example. The study by Morris et al.distinguished between short- and long-latency SCR, and concluded that long(er)-latency SCRs, alone, corresponded to higherratings of familiarity.

Returning specifically to question (iii), the task dependency of the SCR provides some insight into why prosopagnosic pa-tients, despite increased SCR when in the presence of familiar faces, do not experience familiarity of being from which theycan differentiate familiar from unfamiliar faces (even if they are still unable to provide identify-specific information). Theelevated SCR levels produced by prosopagnosic patients are not the product of autonomic arousal brought on by resourceallocation within the face recognition system; rather, they are a measure of the exposure effect noted earlier. In addition,it is not the case that the change in autonomic arousal that underlies the prosopagnosic patient’s elevated SCR does not per-vade consciousness at all; rather, it is that it does not present itself as a feeling of familiarity. However, based on the findingsof Greve and Bauer, it does pervade consciousness as a feeling of preference in forced-choice tests. Recall that the prospog-nosic patient was unable to differentiate familiar from unfamiliar faces above chance, but was able to state a preference forpreviously seen (but unrecognised) faces above chance level. It is my contention that this choice was guided by a sense ofpreference that corresponds to increased SCRs which are, themselves, a measure of the exposure effect.

5. Mapping the discussion points onto a model of facial recognition

The evidence and argument presented thus far, although compatible with the more recent model of facial recognitionproposed by Ellis and Lewis (2001) nevertheless directs us towards minor but not insignificant refinements that need tobe made. The cases of misidentification reported by Rapcsak et al. (1994), for example, inform us of a functional divide inface encoding that is subserved by areas of the right and left hemispheres, respectively. The structural encoding of the faceprior to FRU processing is based on global and local features. Importantly, what is suggested by the phenomenal experienceof Rapcsak et al.’s patients, and also by the hyperfamiliarity reported by Vuilleumier et al. (2003), is that either global or localfeature encoding is sufficient to activate the FRU. The FRU, in turn, initiates a more specific search for the retrieval of person-identity information – PINs access contextual semantic/biographical details, and even name retrieval. The similarity of localor global features to a known face stored in the FRU is sufficient to activate this component of the face recognition system,but is not sufficient to enable more specific person-identity information to be accessed via the PINs and related units. How-ever, the allocation of resources to the retrieval of person-identity information increases autonomic arousal which is mea-sured as elevated SCR. A lack of specific person-identity detail, in conjunction with heightened autonomic response, isregistered by the ‘integrative device’22 (a feature of Ellis and Lewis’ model), and pervades consciousness as a sense of familiar-ity in the form of tartling.

The key functional difference between the patients of Rapcsak et al. and Vuilleumier et al., and those suffering from pros-opagnosia, is that in the latter case there is disrupted activation of the pathway between the FRU and PINs (Breen et al.,2000). Consequently, prosopagnosic patients are either unable to allocate resources to access person-specific information,or initiate only limited processing. However, because there is some activation of the FRU, in certain cases, prosopagnosic pa-tients can distinguish between famous and unknown faces. The limited sense of familiarity experienced by such patientsduring this discriminatory task could be, I suggest, either a measure of the disrupted/weak activations of the PINs, (view en-dorsed by Breen et al.) or the exposure effect (to famous faces). Either way, it falls short of the tartling evident in cases ofhyperfamiliarity, etc. discussed here.

Within the face recognition model, an affective response to familiar faces can manifest itself in different ways with dif-ferent corresponding measures of SCR. To reiterate, one manifestation might occur as a result of resource allocation toward

20 He may then claim to not have available any further information concerning the individual, or extrapolate further and compound the mistake.21 Of course, a sense of familiarity in the form of tartling is a common enough occurrence, even in the absence of pathology or away from the control of an

experimental environment, as the butcher-on-the-bus examples illustrates. For further details on these more ‘everyday’ examples, see Young, Hay, and Ellis(1985).

22 The integrative devise was proposed by Ellis and Lewis as a way of allowing output from the FRU and the ‘affective component’ of the system to beintegrated, thereby allowing a comparison to be made against stored representations.

G. Young / Consciousness and Cognition 18 (2009) 628–638 635

the retrieval of specific person-identity information, another as a result of the exposure effect (recall Morris et al. recordedboth long- and short-latency responses, depending on task). I have argued that the affective response elicited through theexposure effect pervades consciousness as a feeling of preference. This occurs through the integrative device which, inthe case of prosopagnosia, amounts to an absence of the sort of autonomic arousal brought on by resource allocation, alongwith the subsequent absence of specific person-identity information; but the presence of an affective response elicited by theexposure effect. In the context of forced-choice tasks involving judgements of preference, what is salient is a feeling of pref-erence; it is this feeling that, when contextualised, pervades consciousness and guides the choice.

6. Examining the phenomenology of the Capgras delusion

In the case of the Capgras delusion, the patient is able to encode the face in terms of global and local features; the FRU isactivated and specific person-identity information is easily accessed. Of course, the Capgras patient denies that this person iswho they claim to be. Nevertheless, in terms of the face recognition model, PINs are able to access relevant contextualsemantic/biographical information – including a name – based on physical identity alone. If the putative impostor did notclosely (exactly) match the Capgras patient’s wife (for example) then he would not be troubled by her presence in theway he is. After all, the Capgras husband’s denial that the woman in front of him is his wife does not stem from the fact thatshe ‘‘looks nothing like her”. A Capgras patient’s ‘lack of recognition’ is not based on a failure to recognise the physical sim-ilarity between the putative impostor and who he/she is meant to be; rather, the Capgras patient – a husband, in this case –judges the woman in front of him to be an impostor because he does not recognise her as being his wife.23 The fluency ofprocessing in the stages from activation of the FRU to retrieval of specific person-identity information means that there is noincrease in arousal based on additional allocation of resources. What the Capgras patient experiences, one might conjecture,is the opposite of tartling, at least based on the type of functional dissociation evident here. However, it is my view that tounderstand what the Capgras patient actually experiences we must consider again the findings of Greve and Bauer.

Recall that Greve and Bauer’s study demonstrated that the prosopagnosic patient did not make arbitrary choices aboutwhich face he preferred; rather, selection was based on a sense of preference – there was something-it-was-like for himto prefer one face over the other, even if he could not articulate what it was about the face that he preferred. In contrast,I contend that the Capgras patient, despite recognising who the putative impostor is meant to be, lacks the something-it-is-likeness of preference for this person. By this I mean that he has no increase in SCR when presented with the ‘shouldbe familiar’ individual (which, evidence suggests, and I have argued, guides preference choices as a measure of the exposureeffect). Of course, it may be that the Capgras patient would fail to demonstrate the sort of heightened autonomic arousalcharacteristic of increased resource allocation, and therefore fail to demonstrate an increase in SCR, when in a butcher-on-the-bus situation, for example. (It would be interesting to discover if Capgras patients ever experience tartling.) Theimportant point is that they do not experience increased SCR as a measure of the exposure effect; and it is in this respectthat they are dissociated from prosopagnosic patients. But, importantly, whereas the heightened arousal is salient as a senseof preference in the prosopagnosic patient, the absence of arousal is likewise salient, but in a different way, for the Capgraspatient.

But how can the absent or presence of a sense of preference be a feature within the experience of the Capgras patient?After all, to state a preference do we not need to choose between stimuli? Who, then, is the Capgras patient choosing be-tween? He chooses between the currently presented, putative impostor wife, and his memory of his ‘real’ wife. To explain,I draw on an example originally used by Campbell (2001) but in a slightly different context. Campbell argued that in claiming‘‘That woman is not my wife”, what the husband is saying is ‘‘That [currently perceived] woman is not my wife”, and in orderto claim this the husband must be comparing the currently perceived woman with his conscious recollection of the woman(which is in fact his conscious recollection of his wife). Thus, the claim that the woman is not his wife becomes: ‘‘That [cur-rently perceived] woman is not that [remembered] woman (which he remembers as being his wife)”. Because the Capgraspatient recognises the face of the woman as that which is meant to be his wife, he must have compared this perception withhis memory of his wife and, I presume, accessed a whole host of information relating to her (his actual wife) in the process. Itis reasonable to conjecture that these memories are themselves associated with affective states – states pertaining to hisfeelings for her and, presumably, her preferential status (to put it crudely). I say pertaining to his feelings for her becauseit is not clear from research conducted at present whether Capgras patients respond to memories of their wives (or whoeveris considered the impostor) with increased autonomic arousal. However, let us speculate that they do, or at least that theypossess declarative memories of these favourable feelings (they recall that they are fond of their wives, for example).

What the currently perceived face does not do, for the Capgras patient, is induce the same state of autonomic arousal inhim that research has shown typically influences the prosopagnosic patient’s preference choice. Even though the Capgraspatient is not being instructed directly to choose, what he is in fact doing is showing a preference for the memory of his wife

23 Cases of blind patients with Capgras delusion have been documented (e.g. Dalgalarrondo, Fujisawa, & Banzato, 2002; Reid, Young, & Hellawell, 1993) whichsuggests that the deficit in recognition is not restricted to faces and is therefore multi-modal. This has led Lewis, Sherwood, Moselhy, and Ellis (2001) to proposea voice recognition unit (VRU) which operates (mutatis mutandis) much like the FRU with connections to the PINs. It also suggests that double dissociationsbetween modes of recognition can occur. To date, this has not been formally tested but has received some anecdotal support in the case of the Capgras patientwho claimed that the person in front of him was not his father, but did recognise him as such when later speaking to him on the telephone (Ramachandran &Blakeslee, 1998).

636 G. Young / Consciousness and Cognition 18 (2009) 628–638

over the currently perceived wife. Moreover, the Capgras patient also experiences overt recognition. This is important be-cause for the prosopagnosic patient there is no overt recognition; therefore his preference choice is merely a preferencefor one stranger over another. In contrast, because the Capgras patient recognises the physical features of the person in frontof him as those of his wife (or whoever), then, importantly, the absence of autonomic arousal, as measured by SCR, is expe-rienced not as a lack of affective response but as a loss (Young, 2008b). Not only does this create a sense of preference for thewife qua memory but, importantly, it amounts to a sense of estrangement (Young, 2007a, 2007b), because it is not simply thatthe affective response is not present; it is missing.

[O]ne’s spouse is recognised as looking like one’s spouse, but the normal feeling of familiarity is absent (and, indeed, afeeling of unfamiliarity is present) (Bayne & Pacherie, 2004, p. 3).

The negation is salient; it is ‘‘itself part of the experience”; something one is ‘‘struck by” (Ratcliffe, 2004, p. 36).To be clear, then, the patient does not experience an absence of autonomic arousal per se. In other words, the salient nat-

ure of the phenomenal content is not ‘absence of autonomic arousal’; rather, the absence of autonomic arousal pervades con-sciousness as a sense of estrangement. It is this sense of estrangement that is salient: salient qua a loss of preference oremotional connectedness with the person presented, at least compared to how one should feel if this truly were one’s wife(or whoever).

In response to question (ii) (What must it be like to physically recognise x without experiencing familiarity of being towardx?), I would say that the Capgras patient experiences estrangement. The Capgras husband is able to physically recognise x –as someone who looks just like his wife – but at the same time lacks the feeling of connectedness to x that typically guide hispreference choice. The conflict that occurs as a result of recognising the physical similarity between this woman and his wife(qua memory of her), and the preference he feels for the memory of his wife, manifests itself as a feeling of estrangementtowards the putative impostor.

7. Conclusion

To conclude, in the first part of this paper I outlined what I claimed was something of a puzzle within the reported expe-riences of prosopagnosic and Capgras patients. Each is described as lacking a sense familiarity toward familiar faces (per-sons); yet this (apparent) uniform absence occurs in conjunction with an anatomical and functional dissociation in whichdisruption to the ventral-limbic structure (covert route) of the Capgras patient remains unaffected in cases of prosopagnosia.Thus one is left to puzzle over why, if an absence of a sense of familiarity in the Capgras patient is caused by disruption to theventral-limbic structure, the functioning of this same structure does not produce a sense of familiarity in patients withprosopagnosia.

Without wishing to understate the fact, what I hope to have demonstrated is that the experiences of prosopagnosic andCapgras patients are the product of a complex interaction that cannot be understood solely in terms of the isolated disrup-tion of one neural structure over another; neither does each equate to an absence of a sense of familiarity that is experien-tially equivalent. In fact, each experiential state can be distinguished from other states of familiarity that are related tofurther facial recognition pathologies or even findings within the RWI paradigm.

With prosopagnosia, resource allocation is not possible because the pathway between the FRU and PINs is, to a lesser ofgreater extent, dysfunctional; consequently, there can be no experience of tartling.24 The increase in SCR to the presence of afamiliar face is not, in this case, a measure of additional resource allocation to the task of facial identification. Instead, it is ameasure of the exposure effect. This can pervade consciousness when given the appropriate contextual outlet – such as the feel-ing of preference in a forced-choice task – but does not produce the sort of autonomic arousal that is made salient as tartling. Incontrast, the autonomic arousal that occurs in the case of RWI (and also hyperfamiliarity) is based on resource allocation. Thecorresponding SCR (longer-latency, at least in the case of Morris et al.’s study) is therefore a measure of arousal that is not basedon the exposure effect. The combination of absence of physical identification, along with arousal based on resource allocation,produces a sense of tartling, or familiarity of being.

With the Capgras delusion, an interesting empirical question is whether these patients are able to experience tartling. Ifso, then this would suggest that they are likewise able to demonstrate increased autonomic arousal in response to the allo-cation of additional resources to the retrieval of person-identity information, should none be immediately forthcoming. Ifthey cannot, then this would suggest that any form of heightened autonomic response, based on the functioning of the facerecognition system in the retrieval of information via the PINs, is disrupted. As interesting as this question is, however, itis beside the point when it comes to our present focus – because, in the case of the Capgras patient, physical recognitionis immediate. Therefore, there is no need to allocate additional resources toward physical identification, and, consequently,no increase in arousal, irrespective of whether arousal of this kind could occur. The patient is not struck by an experience oftartling; but there is an absence of arousal that in conjunction with physical recognition combines to produce a negation inexperience that is equally salient – so much so that the patient is struck by its absence.

The absence of an increase in autonomic arousal toward the person the patient is currently faced with (his wife, say),alongside the retrieval of contextual semantic/biographical information pertaining to his wife (physical identification), col-

24 In cases of apperceptive prosopagnosia (not discussed in this paper), it is conjectured that the FRU itself is dysfunctional.

G. Young / Consciousness and Cognition 18 (2009) 628–638 637

lude to create an experiential state of preference for the memory of his wife over the currently perceived wife. The negationevident in relation to the currently perceived wife, in comparison to the memory of the wife, creates a sense of loss. A lack ofx is not salient, but its loss is; and its loss can only be experienced relative to some occasion when x was present. The feelingof preference for the wife qua memory results in a failure of an experience of familiarity of being with regard to the currentlyperceived woman/wife. This phenomenal state I have called estrangement. If one wishes to couch the explanation in neuro-logical terms, it is a state that can only be made salient when damage to the ventral-limbic structure occurs in conjunctionwith an intact ventral pathway. Or, in functional terms, it is brought about by a failure to trigger the affective component ofthe face recognition system whilst allowing immediate retrieval of person-identity details via the PINs.

As a final but nevertheless important point, the sense of estrangement experienced by the Capgras patient is not sufficientto produce the delusional belief that the person is an impostor; nor is it the whole story regarding the phenomenologyunderlying the condition; but it should be an integral component within any explanation proffered. The aim of this paperhas not been to provide a full account of how the underlying phenomenology constitutive of the Capgras delusion integrateswith other features of the condition (for a discussion on that, see Young, 2008a); rather, its aim has been to (i) untangle thedifferent descriptions of the phenomenal experiences of patients with two independent yet, according to Ellis and Young’s(1990) mirror-image model, neurologically and functionally related conditions, and (ii) couch any discussion within theframework provided by the most recent model of face recognition – that of Ellis and Lewis (2001).

References

Barton, J. J. S. (2008). Prosopagnosia associated with a left occipitotemporal lesion. Neuropsychologia, 46, 2214–2224.Bauer, R. M. (1984). Autonomic recognition of names and faces in propopsgnosia: A neuropsychological application of the guilty knowledge test.

Neuropsychologia, 22, 457–469.Bayne, T., & Pacherie, E. (2004). Bottom-up or top-down? Campbell’s account of monothematic delusions. Philosophy, Psychiatry, and Psychology, 11(1), 1–11.Bayne, T., & Pacherie, E. (2005). In defence of the doxastic conception of delusions. Mind and Language, 20(2), 163–188.Bobes, M. A., Lopera, F., Garcia, M., Diaz-Comas, L., Galan, L., & Valdes-Sosa, M. (2003). Covert matching of unfamiliar faces in a case of prosopagnosia: An ERP

study. Cortex, 39, 41–56.Bortolotti, L. (2005). Delusions and the background of rationality. Mind and Language, 20(2), 189–208.Brédart, S., & Young, A. W. (2004). Self-recognition in everyday life. Cognitive Neuropsychiatry, 9(3), 183–197.Breen, N., Caine, D., & Coltheart, M. (2000). Models of face recognition and delusional misidentification: A critical review. Cognitive Neuropsychology, 17(1/2/

3), 55–71.Brighetti, G., Bonifacci, P., Borlimi, R., & Ottaviani, C. (2007). Far from the heart far from the eye: Evidence from the Capgras delusion. Cognitive

Neuropsychiatry, 12(3), 189–197.Bruce, V., & Young, A. (1986). Understanding face recognition. British Journal of Psychology, 77, 305–327.Campbell, J. (2001). Rationality, meaning and the analysis of delusion. Philosophy, Psychiatry, and Psychology, 8(2/3), 89–100.Capgras, J., & Reboul-Lachaux, J. (1923). L’illusion des ‘soises’ dans un délire systématisé chronique. Bulletin de la Société Clinique de Médicine Mentale. In

M. D. Enoch & W. H. Trethowan (Eds.), Uncommon psychiatric syndromes (pp. 1979). Bristol: John Wright and Sons Ltd. (11, 6–16).Cleary, A. M., & Greene, R. L. (2000). Recognition without identification. Journal of Experimental Psychology: Learning, Memory and Cognition, 26, 1063–1069.Cleary, A. M., & Specker, L. E. (2007). Recognition without face identification. Memory and Cognition, 35(7), 1610–1619.Coltheart, M. (2007). The 33rd Sir Fredrick Bartlett lecture. Cognitive neuropsychiatry and delusional belief. The Quarterly Journal of Experimental Psychology,

60(8), 1041–1062.Dalgalarrondo, P., Fujisawa, G., & Banzato, C. E. M. (2002). Capgras syndrome and blindness: Against the prosopagnosia hypothesis. The Canadian Journal of

Psychiatry, 47(4), 287–388.Davies, M., & Coltheart, M. (2000). Introduction: Pathologies of belief. Mind and Language, 15(1), 1–46.de Haan, E. H. F., Bauer, R. M., & Greve, K. W. (1992). Behavioral and physiological evidence for covert recognition in a prosopagnosic patient. Cortex, 28,

7–95.Denburg, N.L., Jones, R.D., & Tranel, D. (2009). Recognition without awareness in a patient with simultanagnosia. International Journal of Psychophysiology, 72

(1), 5–12.Ellis, H. D., & Lewis, L. (2001). Capgras delusion: A window on face recognition. Trends in Cognitive Science, 5(4), 149–156.Ellis, H. D., & Young, A. W. (1990). Accounting for delusional misidentification. British Journal of Psychiatry, 157, 239–248.Ellis, H. D., Young, A. W., Quayle, A. H., & de Pauw, K. W. (1997). Reduced autonomic responses to faces in Capgras delusion. Proceedings of the Royal Society:

Biological Science, B264, 1085–1092.Fine, C., Craigie, J., & Gold, I. (2005). Damned if you do; damned if you don’t: The impasse in cognitive accounts of Capgras delusion. Philosophy, Psychiatry,

and Psychology, 12(2), 143–151.Gerrans, P. (1999). Delusional misidentification as subpersonal disintegration. The Monist, 82(4), 590–608.Gilleen, J., & David, A. S. (2005). The cognitive neuropsychiatry of delusions: From psychopathology to neuropsychology and back again. Psychological

Medicine, 35, 5–12.Greve, K. W., & Bauer, R. M. (1990). Implicit learning of new faces in prosopagnosia: An application of the mere exposure paradigm. Neuropsychologia, 28,

1035–1041.Groh-Bordin, C., Zimmer, H. D., & Ecker, U. K. H. (2006). Has the butcher on the bus dyed his hair? When colour changes modulate ERP correlates of

familiarity and recollection. NeuroImage, 32, 1879–1890.Haxby, J. V., Gobbini, M. I., Furey, M. L., Ishai, A., Schouten, J. L., & Pietrini, P. (2001). Distributed and overlapping representations of faces and objects in

ventral temporal cortex. Science, 293, 2425–2430.Haxby, J. V., Hoffman, E. A., & Gobbini, M. I. (2000). The distributed human neural system for face perception. Trends in Cognitive Science, 4(6), 223–233.Hirstein, W., & Ramachandran, V. S. (1997). Capgras’ syndrome: A novel probe for understanding the neural representation of the identity of familiarity of

persons. Proceedings of the Royal Society: Biological Sciences, B246, 437–444.Hohwy, J. (2004). Top-down and bottom-up in delusion formation. Philosophy, Psychiatry, and Psychology, 11(1), 65–70.Jacoby, L. L., & Dallas, M. (1981). On the relationship between autobiographical memory and perceptual learning. Journal of Experimental Psychology: General,

110, 306–340.Jacoby, L. L., & Whitehouse, K. (1989). An illusion of memory: False recognition influenced by unconscious perception. Journal of Experimental Psychology:

General, 118, 126–135.Johnston, W., Dark, V. J., & Jacoby, L. L. (1985). Perceptual fluency and recognition judgements. Journal of Experimental Psychology: Learning, Memory and

Cognition, 11, 3–11.Kelly, C. M., & Jacoby, L. L. (1990). The construction of subjective experience: Memory attributions. Mind and Language, 5, 49–68.Klee, R. (2004). Why some delusions are necessarily inexplicable beliefs. Philosophy, Psychiatry, and Psychology, 11(1), 25–34.

638 G. Young / Consciousness and Cognition 18 (2009) 628–638

Lewis, M. B., Sherwood, S., Moselhy, H., & Ellis, H. D. (2001). Autonomic responses to familiar faces without autonomic responses to familiar voices: Evidencefor voice-specific Capgras delusion. Cognitive Neuropsychiatry, 6(3), 217–228.

Lyon, G. (1996). The experience of perceptual familiarity. Philosophy, 71, 83–100.Mandler, G. (1980). Recognizing: The judgement of previous occurrence. Psychological Review, 87, 252–271.Morris, A. L., Cleary, A. M., & Still, M. L. (2008). The role of autonomic arousal in feelings of familiarity. Consciousness and Cognition, 17, 1378–1385.Nagel, T. (1974). What is it like to be a bat? Philosophical Review, 83(4), 435–450.Pannu, J. K., Kaszniak, A. W., & Rapcsak, S. Z. (2005). Metamemory for faces following frontal lobe damage. Journal of the International Neuropsychological

Society, 11, 668–676.Peynircioglu, Z. (1990). A feeling-of-recognition without identification. Journal of Memory and Language, 29, 493–500.Phillips, J. (2002). Arguing from neuroscience in psychiatry. Philosophy, Psychiatry, and Psychology, 9(1), 61–63.Ramachandran, V. S., & Blakeslee, S. (1998). Phantoms in the brain: Probing the mysteries of the human mind. New York: William Morrow.Rapcsak, S. Z., Nielsen, L., & Littrell, L. D. (2001). Face memory impairments in patients with frontal lobe damage. Neurology, 57, 1168–1175.Rapcsak, S. Z., Polster, M. R., Comer, J. F., & Rubens, A. B. (1994). False recognition and misidentification of faces following right hemisphere damage. Cortex,

30, 565–583.Rapcsak, S. Z., Polster, M. R., Glisky, M. L., & Comer, J. F. (1996). False recognition of unfamiliar faces following right hemisphere damage: Neuropsychological

and anatomical observations. Cortex, 32, 593–611.Rapcsak, S. Z., Reminger, S. L., Glisky, E. L., Kaszniak, A. W., & Comer, J. F. (1999). Neuropsychological mechanisms of false facial recognition following frontal

lobe damage. Cognitive Neuropsychology, 16(3/4/5), 267–292.Ratcliffe, M. (2004). Interpreting delusions. Phenomenology and Cognitive Sciences, 3, 25–48.Reid, I., Young, A. W., & Hellawell, D. J. (1993). Voice recognition impairment in a blind Capgras patient. Behavioural Neurology, 6(4), 225–228.Renault, B., Signoret, J., Debruille, B., Breton, F., & Bolgert, F. (1989). Brain potentials reveal covert facial recognition in prosopagnosia. Neuropsychologia, 27,

905–912.Rossion, B., Dricot, L., Devolder, A., Bodart, J. M., Crommelinck, M., De Gelder, B., et al (2000). Hemispheric asymmetries for whole-based and part-based face

processing in the human fusiform gyrus. Journal of Cognitive Neuroscience, 12, 793–802.Schweinberger, S. R., & Burton, MA. (2003). Covert recognition and the neural system for face processing. Cortex, 39, 9–30.Stone, A., & Valentine, T. (2003). Perspectives on prosopagnosia and models of face recognition. Cortex, 39, 31–40.Stone, T., & Young, A. W. (1997). Delusions and brain injury: The philosophy and psychology of belief. Mind and Language, 12(3/4), 327–364.Stormark, K. M. (2004). Skin conductance and heart-rate responses as indices of covert face recognition in preschool children. Infant and Child Development,

13, 423–433.Tanaka, J. W., & Farah, M. J. (1993). Parts and wholes in face recognition. Quarterly Journal of Experimental Psychology, 225–245.Tranel, D., & Damasio, A. R. (1985). Knowledge without awareness: An automatic index of facial recognition by prosopagnosics. Science, 228, 1453–1454.Verstichel, P. (2005). False recognition of faces associated with fronto-temporal dementia with prosopagnosia. Revue Neurologique, 16(8–9), 804–816.Vuilleumier, P., Mohr, C., Valenza, N., Wetzel, C., & Landis, T. (2003). Hyperfamiliarity for unknown faces after left lateral temporo-occipital venous

infarction: A double dissociation with prosopagnosia. Brain, 126, 889–907.Young, A. W., Hay, D. C., & Ellis, A. W. (1985). The faces that launched a thousand slips: Everyday difficulties and errors in recognizing people. British Journal

of Psychology, 76, 495–523.Young, A. W., & de Pauw, K. W. (2002). One stage is not enough. Philosophy, Psychiatry, and Psychology, 9(1), 55–59.Young, A. W. (1999). Delusions. The Monist, 82(4), 571–589.Young, G. (2007a). Clarifying ‘Familiarity’: Examining differences in the phenomenal experiences of patients suffering from prosopagnosia and Capgras

delusion. Philosophy, Psychiatry, and Psychology, 14(1), 29–37.Young, G. (2007b). In defense of estrangement. Philosophy, Psychiatry, and Psychology, 14(1), 51–56.Young, G. (2008a). Capgras delusion: An interactionist model. Consciousness and Cognition, 17(3), 863–876.Young, G. (2008b). Restating the role of phenomenal experience in the formation and maintenance of the Capgras delusion. Phenomenology and the Cognitive

Sciences, 7(2), 177–189.Yovel, G., & Paller, K. A. (2004). The neural basis of the butcher-on-the-bus phenomenon: When a face seems familiar but is not remembered. NeuroImage,

21, 789–800.Zajonc, R. B. (1980). Feeling and thinking: Preferences need no inferences. American Psychologist, 35, 151–175.Zajonc, R. B. (2000). Feeling and thinking: Closing the debate over the independence of affect. In J. P. Forgas (Ed.), Feeling and thinking: The role of affect in

social cognition (pp. 31–58). Cambridge: Cambridge University Press.Zajonc, R. B. (2001). Mere exposure: A gateway to the subliminal. Current Directions in Psychological Science, 10(6), 224–228.

Garry Young is currently a senior lecturer in the Division of Psychology, Nottingham Trent University. His research interests include concepts andexperiences of self in cyberspace, pre-conscious embodied interaction, the relationship between consciousness and knowledge, and delusional misi-dentification (particularly the Capgras delusion).