During the last quarter of the last century, the physiol-ogy of animal and human behavior made a decisive transi-tion from the ideology of the “reactive model,” based on theprinciples of biological determinism (stimulus – neurody-namics – response) to a model of the active organism. Thetransition was so dramatic that it became known as the “cog-nitive revolution” in the western literature [19]. Thisunavoidably required a return of concepts of consciousnessand unconsciousness to the categorial apparatus of humanbehavioral physiology before completely discarding themfrom further consideration. The need has arisen for psy-chophysiologists to define the concepts of consciousness,awareness, self-awareness, and many unconscious mentalmanifestations, in order to answer their questions.

For the psychophysiologist, the best definition of theconcept of consciousness is based on the theory of commu-nicativity – “knowledge with another person” [12, 13], i.e.,knowledge which can be transmitted, communicated toanother person with words, mathematical symbols, artisticimages, or voluntary actions substituting for these, such thatthey become an achievement for other members of society.

This is adequate for experimental studies of the regulatoryrole of consciousness in the cognitive activity of humansfrom the point of view of determinism. However, it isimportant to emphasize that consciousness is not only areflection of the features of the surrounding world, normerely some knowledge of these features, but also the rela-tionship of the subject with the surrounding world.Therefore, the subject of the concept of consciousness alsoincludes intrinsic mental phenomena and human experi-ence, i.e., it is not only a process of awareness of the exter-nal world and the ability to transmit knowledge about it toanother person, but also an awareness of the self, an abilityto give an account of what occurs in the individual’s mentalworld. Consciousness is analogous to a social contact of ahuman with himself, a process which involves the forma-tion of a defined concept not only of the external world, butalso of the self, the subjective image of “I”. This relation-ship of the subject to his awareness of being is conscious-ness. Thus, apart from the communicative role, anotherimportant aspect of consciousness must be recognized: itrepresents social contact of a human with himself as a resultof “generalization of internal mental forms of activity” [4].

Many experimental data and psychological and clini-cal observations have accumulated showing that “internalmental forms of activity” can form at the unconscious level

Neuroscience and Behavioral Physiology, Vol. 37, No. 4, 2007

Significance of the Context of Cognitive Activity in the Formation of Unconscious Visual Sets

É. A. Kostandov

0097-0549/07/3704-0321 ©2007 Springer Science+Business Media, Inc.

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Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 92, No. 2, pp. 164–177,February, 2006. Original article submitted July 1, 2005.

Experimental data from healthy humans on the context dependence of cognitive activity involved in theprocess of substituting a previously formed unconscious set with a new set appropriate to the altered con-ditions are discussed. The mobility/rigidity property of the visual set changes depending on the nature ofthe additional task introduced into the context (stimulus recognition or identification of the spatial posi-tion of a stimulus). It is hypothesized that the process of set substitution is facilitated when the context ofcognitive activity includes alternation of the involvement of the ventral and dorsal visual systems in infor-mation processing.

KEY WORDS: cognitive set, dorsal and ventral visual systems, unconsciousness, working memory, visual illusions,“word blindness.”

Institute of Higher Nervous Activity and Neurophysiology,Russian Academy of Sciences, 5a Butlerov Street,117485 Moscow, Russia.

and play an important role in controlling voluntary behav-ior in humans. Their origin is not obligately associated withthe emotions and unconscious inclinations, as claimed byFreud. In the contemporary psychophysiological literature,these are referred to using the single general and quite unde-fined concept of the “internal state.” There are also concreteterms: set, context, scheme, internal representation, hypoth-esis. All of these are combined into a single fundamentalcase: the actions of conscious and unconscious stimuli on ahuman create an integrated image in the higher parts of thebrain which, according to Uznadze [14] and Beritashvili[2], is termed the set. Psychological studies of the set areassociated with the name of Uznadze [14]. Beritashvili [3]used this concept, in particular, to explain the phenomenonof conditioned reflex switching. He regarded the set as afunctional state in the form of a tonic increase in excitabil-ity in the corresponding nerve centers of the brain, creatingreadiness for a particular behavior and determining thedirection of the overall behavior in a concrete situation.

The abundance of terms appears to be explicable not somuch by the variety of internal states as by the poor level ofstudy of their neurophysiological bases. Scientific study of“internal states” has only been started in recent years and isstill largely at the level of obtaining phenomenologicaldescriptions of the facts of their influences on the functionsof perception and the search for brain structures with keyroles in their formation. We believe that the term cognitiveset provides the most complete reflection of the phe-nomenology of the manifestation, which is directly relatedto the sphere of cognitive activity.

The phenomenon of the set has been described duringthe perception of stimuli of different modalities, both non-verbal and verbal. All types and forms of sets unite a singlebasic position: repeated perception of a concrete stimulusand the situation in which it acts on a person has the resultthat a functional state forms in the higher parts of the brain;this has the form of an increased excitability of particularneuron complexes, which to a significant extent organizethe readiness of the subject to perceive this stimulus, antic-ipating solution of the perceptual task and, thus, having aregulatory action on the subject’s behavior.

One further important position should be emphasized:the subject is aware of neither the set itself nor the fact of itsformation, and does not experience it at the conscious level.This was demonstrated in experiments in which contextualtests were performed in humans in the state of hypnoticsleep. Despite being in this state, subjects showed the effectof the set in critical tests [14]. These and many other dataprovide grounds for agreeing with the general theory ofUznadze, that the set forms without involving conscious-ness and is not a phenomenon of consciousness, but reflectsbrain processes which organize the internal state at theunconscious level; the internal state to a significant extentanticipates solution of the cognitive task at the consciouslevel, such that in a given concrete situation the subject’s

approach to a particular activity and his readiness for theappropriate form of response are pre-formed.

Contemporary models of cognitive behavior regardperception of an external object as a process of comparisonof sensory information with an internal representation, i.e.,knowledge of these objects stored in a human’s workingmemory – a set. At the unconscious level, this mechanismensures initial rapid extraction of representations or con-cepts of a defined class from memory, i.e., those showingthe greatest correspondence to the type of stimulus acting.The result is preliminary analysis, classification, and inter-pretation of incoming information at the early stages of theprocess of perception with subsequent transmission ofthe results of information processing from the prefrontalareas to the cortical structures responsible for the final, nowconscious, recognition of a verbal or nonverbal stimulus.In cases in which sensory information coincides with anexisting set, cognitive activity is significantly facilitated.This is clearly evident from the example of experimentsusing pseudowords.

Reading of meaningless pseudowords consisting ofLatin letters, with time pressure created by the experimen-tal conditions, imposes some degree of mental tension onhumans [5]. Those subjects who form a sufficiently stableset for pseudoword recognition have an advantage. Asshown by data on reaction times for test stimuli, such peo-ple can switch more quickly to another cognitive activityand, judging from EEG data, experience less mental ten-sion. However, when the situation changes such that sub-jects have to recognize common Russian words instead ofpseudowords, the stable set previously formed on readingpseudowords serves to interfere with the recognition of nor-mal words: so-called “word blindness” is seen during aseries of trials – the subject, in clear consciousness, does notrecognize common words but continues to perceive them aspseudowords. In these trials, there is an obvious discor-dance between the incoming sensory information and thepreviously formed internal representation, i.e., the set –between the ascending and descending nervous spikestreams, whose interaction and integration organize the pro-cess of stimulus recognition. Similar results were obtainedin experiments involving the formation of a nonverbal visu-al set in which the subjects had to evaluate the relative sizesof two circles. In these cases, discordance between the newstimuli and the set led to distortion of perception, with theappearance of contrast-type visual illusions [7].

Thus, two aspects of the unconscious set in the corticalorganization of cognitive functions can be defined. On theone hand, concordance of incoming sensory informationwith the set held in working memory significantly facili-tates cognitive activity, i.e., recognition of the stimulus, itsevaluation, and decision-taking; this occurs in conditions ofa more ordered operation of the higher parts of the centralnervous system, on the background of “calmer” corticalelectrical activity, as compared with cases in which a stable

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set has not been formed. This is the essence of the organi-zation and regulatory role of the set in cognitive processes.This requires the set to be formed in a sufficiently stableform. On the other hand, formation of a rigid set, changesin the situation, and incoming stimuli can result in discor-dance between the new stimulus and this set, which is nolonger appropriate to the changing situation, which resultsin distortions which hinder the process of perception (illu-sions, “word blindness”). In these cases, the process ofstimulus recognition apparently comes to be dominated bydescending spike streams originating in the rigid set storedin the human’s working memory.

This leads us to agree with the position formulated byUznadze [14], that in a constantly changing environment,successful cognitive activity is supported by a particularoptimum in the mobility of sets – their ability to undergoextinction and replacement by new sets appropriate to thechanging situation. It seems to follow that the process ofintegration of ascending and descending nerve spikestreams, as the basis of the function of awareness of exter-nal signals [22], depends on the functional state of uncon-scious sets, particularly stable (rigid) sets. It is important toemphasize that quantitative measurements can be made ofthis property of the cognitive set, by counting the numberof trials showing impaired perception and assessment ofnew stimuli presented in place of old stimuli. The greaterthe number of trials showing distorted perception after stim-ulus substitution, the greater the stability (inertness, rigidi-ty) of the set.

From this it is evident that the most important problemin experimental studies of internal states – sets – is the iden-tification of the factors responsible for the stability of sets.Studies of personality characteristics using the Kettel ques-tionnaire [18] showed that subjects with a rigid set have lowindependence. They are conscientious, careful, precise, andaccurate, love order in everything, try not to break rules, but

are not very penetrative, even naive, tending to take muchon trust. Subjects with relatively mobile sets are morequick-thinking, operate easily with abstract concepts, andrapidly assimilate novelty. They are emotionally equilibrat-ed, independent in decision-taking, penetrative, criticallytuned to surrounding activity, independent in their judg-ments, and resistant to limitation of personal initiative.Difficulties in this important and interesting problem ofstudying the role of individual personality characteristics inthe formation of sets are to a significant extent associatedwith limitations to obtaining reliable measures of an indi-vidual’s personality. New and more objective assessmentmethods are needed.

An interesting and at first glance unexpected relation-ship was found between set rigidity and the level of a sub-ject’s motivation in relation to the results of his activity.Increases in motivation were found to be able to lead toincreases in the inertness of formed unconscious sets [5].Increases in set inertness on the background of increasedmotivation had the result that in a significant number of tri-als, subjects (students at an élite institute) were unable tosolve a simple cognitive task consisting of adequate evalu-ation of the sizes of equal circles. They demonstrated con-trast-type visual illusions, as the effect of the set persisted.At this point, it is appropriate to cite Anokhin [1], whobelieved that the most likely neural mechanism increasing“pre-existing cryptic dominance” was the action of ascend-ing activatory influences from the hypothalamus and retic-ular system, which “read” this dominant. The suggestionthat “motivated” subjects have more marked ascending acti-vatory influences from motivation-related subcortical struc-tures, based on the fact that these solve cognitive tasks inthe state of mental tension, was supported by spectral anal-ysis of cortical electrical activity in experiments involvingthe formation of visual set [11].

Increases in the rigidity of a visual set, i.e., increaseshindering its replacement by a new set appropriate to thechanging conditions seen when the subject’s motivationincreased, can have a negative effect: the inert internal state(the dominant) prevents appropriate perception and correctassessment of new visual stimuli as the situation changes.This possible negative effect of increased motivation inhumans in relation to the result of their ongoing activitymust be considered, especially in cases in which operativework is associated with a changing situation and cognitivetasks.

Numerous experiments have demonstrated a clear rela-tionship between the extent of set rigidity and the complex-ity and volume of cognitive activity being performed by thesubject. This has been shown in experiments in whichthe subject had to solve two sequential tasks in a single trial:one consisting of recognition of a pseudoword/word, fol-lowed by another involving identification of the ratio of thesizes of two circles displayed on a monitor screen 1 secafter the verbal stimulus, pressing a key in response to the

Significance of the Context of Cognitive Activity in the Formation of Unconscious Visual Sets 323

Fig. 1. Distribution of subjects in terms of the numbers of trials with con-trast-type illusions in experimental series with circles (light columns) andcircles + words (dark columns). The vertical axis shows the numbers ofsubjects; the horizontal axis shows the numbers of trials with illusions.

test stimulus (a point of light at the center of the screen) andthen say out loud the pseudoword/word read and report theassessment of the sizes of the circles. As compared withexperiments in which only the verbal stimulus recognitiontest was performed, increases in the complexity of the con-text significantly increase the load on working memory: thesubject has to read the pseudoword/word to himself,remember it, compare the sizes of two circles, decide whichis the larger, remember the result of this decision, and thenpress a key when the test stimulus appears, then sayingthe pseudoword/word read in the test out loud and report theassessment of the sizes of the circles.

These experiments showed that increases in the com-plexity of the mental activity, when a human subject has tosolve several cognitive tasks sequentially in a short periodof time, significantly increase the inertness of the uncon-scious visual sets formed during this activity. Substitutionof this set by a new set appropriate to the changing condi-tions occurs with difficulty, requiring a larger number of tri-als (Figs. 1 and 2). This increases the duration of the periodof discordance between the new stimuli and the previouslyformed internal state, which in our experiments leads tolonger-lasting “word blindness” or contrast-type illusions.

Special experiments showed that the inertness of bothverbal and nonverbal visual sets is not significantly relatedto their positions in the context of the cognitive tasks beingsolved by the subject [5, 7]. These results provide groundsfor considering that the factor switching selective attentionis not of decisive importance in increasing set inertness asthe number of cognitive tasks increases. It is possible thatthe minor role for the function of selective attention isbecause the sets investigated in our studies do not form atthe unconscious level without the involvement of con-sciousness. Another suggestion seems appropriate: setrigidity is to a significant extent determined by the volumeof operative information which has to be held in working

memory for “on-line” solving of a series of cognitive tasks.We note that working memory is a special type of memoryactively storing memory traces – engrams – after a relevantstimulus ends, along with information retrieved from long-term memory for the short time needed for its use in sup-porting cognitive activity. This type of memory is unam-biguously associated with structures in the prefrontal cortex[20, 21, 23, 24, 27, 41], which are also key structures for theformation of cognitive sets.

fMRI studies of cortical activity have supported ourhypothesis regarding the relationship between the mobilityof unconscious visual sets and the magnitude of loading onworking memory. Thus, increases in loading on workingmemory by supplementation of a semantic task with anoth-er – a visuospatial task – significantly increased bilateralactivation of the dorsolateral prefrontal cortex in healthysubjects [23]. It is interesting that when the load on work-ing memory was not increased but the single semantic taskwas made more complex, this increase in activity in the pre-frontal cortex did not occur, though activity in other corticalzones did increase. The authors of this study concluded thatthe dorsolateral prefrontal cortex is specifically involved incortical activity when there is a need to solve two sequen-tial cognitive tasks within a short period of time. Each ofthese alone produced no such effect. The authors believedthat this cortical structure is involved in the displacementand coordination of attention resources – a process based onworking memory which is needed for the performance ofmultiple cognitive functions.

fMRI studies have demonstrated that increases in theactivity in the same parts of the lower prefrontal cortex areassociated with the function of working memory and theformation of a cognitive set using the Wisconsin test [32,33, 38]. The authors of these studies concluded that the pre-frontal cortex is involved both in functions changing cogni-tive sets and in working memory, which support flexibleadaptation to changing environmental conditions. Thispoint of view was supported by data obtained in patientswith organic lesions of the frontal lobes [40]. These patientshave impairments in the card-sorting test and the Wisconsintest in relation to identifiable criteria which they have toacquire on the basis of feedback (“correct” – “incorrect”).These impairments are particularly marked when subjectshave to change the internal criteria which they have formedin accord with the new conditions of the task. These patientsare not in a switching state, i.e., a state to form new criteriaappropriate to the changing conditions and continue tosolve the task using the previous criteria.

Indirect but strong evidence for a relationship betweenthe prefrontal cortex and the processes of the formation andsubstitution of cognitive sets is also provided by ontogenet-ic studies [40]. This investigation showed that the formationand substitution of nonverbal visual sets (experiments withimages of circles in children aged 9–10 years) were not sig-nificantly different from those observed in adults. Accor-

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Fig. 2. Distribution of subjects in terms of the numbers of trials in whichthey failed to recognize verbal stimuli in experiments with pseu-dowords/words (light columns) and experiments with pseudowords/words+ circles (dark columns). The vertical axis shows the numbers of subjects;the horizontal axis shows the numbers of trials showing word blindness.

ding to data obtained by Tsekhmistrenko [16], a significantmaturation of the structural organization of the frontal areasof the cortex occurs at this age, particularly with an increasein the size of pyramidal neurons: virtually all neuronsacquire a specialized shape and fibers in sublayer 3, whichsupport intracortical horizontal connections, developintensely. Structural rearrangements by age 9–10 yearscomplete the development of the mechanism of voluntaryattention (in terms of EEG parameters), which supports theprocess of recognition of significant signals [15, 34]. Thisage is regarded as a “sensitive period in the formation ofvoluntary attention and, on this basis, completion of thefunctional organization of different types of voluntary activ-ity, which significantly increases the efficiency of their per-formance” ([15], p. 100). It should be noted that in childrenof preschool age, from 5.3 to 6.1 years, the set was signifi-cantly more inert and that substitution of one set by a newset, appropriate to the changing conditions, occurred signif-icantly more slowly than in children aged 9–10 years. Thesedata show that successful support of changes of setsrequires morphofunctional maturation of the frontal cortex.

Thus, a series of experimental facts were obtainedwhich indicated that the process of substitution of uncon-scious sets is associated with the function of working mem-ory: increases in loading on working memory hinder theextinction of the old set and the formation of the new setmore appropriate to the changing conditions. It shouldagain be noted that both of these functions occur with theinvolvement of the same structures of the prefrontal cortex[22, 24, 33, 38]. However, during experiments on the rela-tionship between unconscious visual sets and the context ofcognitive activity it was noted that this relationship is not asstraightforward as we previously believed: in trials in whichthe load on working memory was increased by introducingan additional visuospatial task of the “where?” type (identi-

fication of the position of a target stimulus), changes in therigidity of the visual set were significantly different fromthose affecting this set property when the additional taskconsisted of recognizing the stimulus, i.e., was of the“what?” type (recognition of two circles and assessment oftheir size ratio).

Measures of the rigidity of a nonverbal visual set werecompared in three series of experiments: 1) controls, withpresentation only of set stimuli (images of circles); 2) anadditional task consisting of recognizing pseudowords/wordswas introduced into the context of experiments with imagesof circles; 3) the additional task consisted of identifying thespatial position of a target stimulus in a matrix of letters.Comparison of the numbers of trials producing contrast-type illusions in these three series of experiments (Figs. 1and 3) showed what we believe to be an interesting obser-vation: a significant reduction in the rigidity of the nonver-bal set on addition of a visuospatial task and, conversely, anincrease in the rigidity of this same set on addition of a testbased on recognition of stimulus quality. It is interestingthat facilitation of the change in set to one more appropriateto the new conditions was also seen in comparison with thefirst series of experiments, in which there was no addition-al task.

We assigned ourselves the difficult task of understand-ing the neurophysiological basis of differences in the stabil-ity of the unconscious visual set depending on the contextof the cognitive tasks being solved. It was necessary to findan explanation for the experimental facts showing oppositechanges (depending on the nature of the complication of thecognitive activity) in the rigidity of the unconscious setsformed. It should be noted that addition of a visuospatialtask to the concept, as we believe, imposes at least as greata loading on working memory as the situation in which theadditional task is associated with recognition of verbal stim-uli. It became evident that changes in the ability to changethe set to one more appropriate to the new conditions can-not be explained in terms of the working memory loadingfactor alone. We suggested the hypothesis that there is arelationship between the inertness of visual sets and thecontext of the cognitive tasks whose solutions predomi-nantly involve different visual systems.

As long ago as 1982, Mishkin et al. [37] identified twovisual information processing systems in the cerebral cor-tex: the ventral stream and the dorsal stream (Fig. 4).Subsequent neuropsychological and clinical-morphologicalstudies of patients with organic lesions and experiments onmonkeys supported the existence of two major projectionsfrom the occipital visual areas of the cortex [28–30, 35, 36].

The ventral stream projects to the inferior temporalcortex. This system is responsible for processing visualinformation relating to the properties of perceived objects,converting the information into visual images and support-ing the identification of the objects, i.e., it answers the ques-tion of “what” the human or animal sees. The dorsal stream

Significance of the Context of Cognitive Activity in the Formation of Unconscious Visual Sets 325

Fig. 3. Distribution of subjects in terms of the numbers of trials with con-trast-type illusions in experiments with circles (light columns) and experi-ments with circles + visuospatial task (dark columns). The vertical axisshows the numbers of subjects; the horizontal axis shows the numbers oftrials with illusions.

of nerve spikes from the occipital zones of the visual cortexarrives in the posterior parietal cortex. This system relatesto the processing of visual information identifying the loca-tion and disposition of external objects at a specific point intime, i.e., it answers the question “where?” The ventral anddorsal visual systems evidently operate in tight cooperation,performing on the one hand the function of stimulus recog-nition and assessment of stimulus significance and, on theother hand, the location of the stimulus in space, forthe organization of directed behavior.

There are good grounds to believe that the activity ofeach of these visual systems is modulated by two differentneural mechanisms of selective attention: the anterior, i.e.,the prefrontal cortex-mediobasal nucleus of the thalamus(ventral system), and the posterior parietal (dorsal system).The inferior parietal cortex (Brodman field 7) is involved inmediating voluntary focused visual attention. This area con-tains gaze fixation and visual following neurons not direct-ly associated with the oculomotor apparatus [39]. Thisstructural-functional formation comprises the requiredcomponent of the dorsal system associated predominantlywith the performance of visuospatial functions.

EEG coherence analysis in the three series of experi-ments discussed above, with formation of a nonverbal visu-al set, showed that changes in the spatial frequency organi-zation of cortical electrical activity differ significantlydepending on the nature of the additional task (Fig. 5). If theadditional task was to recognize a verbal stimulus, coher-ence relationships between cortical potentials in the alpharange increased (as compared with data in the first series ofexperiments, without the additional task) in the frontal-tem-poral-parietal zone of the left hemisphere. Supplementationof the context with a visuospatial task resulted in greaterincreases in coherence connections in the anterior areas ofthe right hemisphere. It should be noted that these differ-ences were most clearly apparent in the low-frequency sub-

range of the alpha rhythm (8–10 Hz). This suggests thatchanges in the coherence of potentials in the alpha rangereflect different types of cognitive activity: recognition of averbal stimulus in one case and identification of the spatialposition of a target object in the other [8].

Thus, the results obtained in three series of experi-ments allowing analysis of the rigidity of nonverbal visualsets provided grounds to conclude that relatively rapid sub-stitution of sets occurs in conditions in which, in the contextof cognitive activity, there is alternation of tasks of differentnature whose solution involves the alternating predominantinvolvement of the ventral and dorsal visual systems and,accordingly, the anterior and posterior cerebral selectiveattention systems.

It was necessary to determine whether there is a simi-lar relationship between the set and the context of cognitivetasks on formation of verbal visual sets. Experiments havedemonstrated that a relationship does undoubtedly exist.In studies using pseudowords/words, the situation in whichthe additional task consisted of the recognition and dis-crimination of two circles, the verbal set formed in theseconditions was markedly more rigid as compared with thesituation in experiments without an additional task [7].The effect of this was that at the test stage of the experi-ment, the subject could not recognize a common word in alarge number of trials, perceiving it as a pseudoword inaccord with the set previously formed in response to theperception of pseudowords.

Substitution of the additional task by a visuospatialtask analogous to that used in the experiment with the non-verbal set, unlike these latter experiments, did not lead tofacilitation of the substitution of verbal sets but, converse-ly, increased their rigidity, i.e., essentially the same picturewas seen as that when the additional task consisted of rec-ognizing circles. In other words, the facilitation of the pro-cess of set substitution predicted by our hypothesis in con-ditions of alternation of involvement of the ventral and dor-sal visual systems in information processing in the contextof cognitive activity. Two explanations can be suggestedfor this: 1) our hypothesis applies only in relation to non-verbal cognitive activity and is not applicable to sets of theverbal type, whose organization involves other, more com-plex, structural-functional systems in the human brain;2) the approach used for measuring the spatial position ofthe target letter in the matrix did not adequately excludethe need to recognize and discriminate the letters, i.e., theinvolvement of the ventral visual system. We note that inthese experiments, as in those described above on the non-verbal set, the signs in the matrix consisted of two differ-ent letters in green and red and, before identifying the posi-tion of one of the letters (a red letter T), the subject had todifferentiate it from the other signs on the matrix. In thepresent case, a small proportion of cortical informationprocessing evidently involves the “what?” visual system,i.e., the ventral system.

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Fig. 4. Diagram of the ventral (light arrows) and dorsal (dark arrows) visu-al streams in the human cerebral cortex. From http://www/ssc/uwo/ca/psychology/faculty/goodale/research.

With the aim of verifying our views, a variant of theadditional task was proposed, in which the need to recog-nize and discriminate letters was minimized by makingthe only significant characteristic of the target stimulus (thecolor of the sign) easily detectable in the matrix and ensur-ing that the subjects were already familiarized with the task.In addition, the visual-spatial task itself was made signifi-cantly more complex. We believe that this made it possibleto discuss more precisely the predominant involvement ofthe dorsal visual system in cognitive functions.

The new version of the additional visual-spatial taskshowed a clear facilitation of the process of substitution ofverbal sets: at the test stage of the experiments, the numberof trials in which the word was not recognized was signifi-cantly smaller than when the supplementary task was notapplied (χ2 = 8.5; df = 5; p < 0.05), and particularly as com-pared with the first version, where the subject had to recog-nize and discriminate the target stimulus (χ2 = 13.5; df = 5;p < 0.005).

These experimental data provide convincing supportfor our hypothesis on the relationship between the substitu-tion of unconscious sets, both nonverbal and verbal, and thecontext of the cognitive functions whose performance pre-

dominantly requires involvement of the ventral and dorsalvisual systems.

The cerebral mechanisms of the relationship betweenthe process of set substitution and set rigidity/mobility on theone hand and the context of cognitive activity predominantlyinvolving the ventral or dorsal visual systems on the other canonly be addressed by logical suggestions based on indirectdata. In trials in which both visual tasks are solved with theinvolvement of structures of the ventral system, it is possiblethat cognitive activity predominantly involves the anteriorfrontothalamic voluntary attention system with its limitedfunctional resources. In these situations, the need to distributeattention between two tasks during a relatively short period oftime may lead to decreases in the activity of structures in theprefrontal cortex associated with the process of set substitu-tion [33, 38]. A different picture is seen in experiments inwhich cognitive tasks are solved by different visual systems,i.e., by the alternating involvement of the anterior frontotha-lamic selective attention system (the ventral visual system)and the parietal visual following structure, which is closelyassociated with the dorsal visual system.

Sequential involvement of the two cerebral visualattention systems in cognitive activity evidently creates

Significance of the Context of Cognitive Activity in the Formation of Unconscious Visual Sets 327

Fig. 5. Plots showing coherence relationships between potentials in the alpha-1 range (8–10 Hz) at different stages of the set in dif-ferent experimental situations. A) Series of experiments with circles; B) circles + pseudowords/words; C) circles + visuospatial task.1) State of “operative rest” (baseline after subjects received instructions); 2) set formation; 3) actualization of the set (presence ofcontrast-type illusions); 4) no visual illusions, i.e., the effect of the set, assessed verbally, has been extinguished.

more favorable conditions for the operation of prefrontalstructures involved in substitution of unconscious cognitivesets when situations change. These essentially theoreticalconsiderations are supported by data from coherence analy-sis of cortical electrical activity in the alpha range obtainedin experiments involving the formation of a nonverbal visu-al set [19]. In trials in which the additional task consisted ofrecognizing a verbal stimulus, coherence relationships weremarked in the frontal-temporal-parietal zone of the lefthemisphere. When a visuospatial task was added to the con-text, coherence relationships were more marked in the ante-rior areas of the right hemisphere. Solution of cognitivetasks requiring the involvement of the ventral or dorsalvisual systems evidently involves various visual attentionbrain structures – the anterior and posterior, as described inthe 1970s [26, 39, 42].

CONCLUSIONS

The relationship seen between the conservatism ofnonverbal and verbal visual sets and the context of cognitiveactivity leads to several conclusions.

The ability to substitute visual sets in response tochanges in the situation or incoming stimuli depends on thefunction of working memory – this has been demonstratedexperimentally. However, significant importance is attachedto the context of cognitive activity whose performanceinvolves a greater or lesser degree of participation of theventral and dorsal visual systems.

The paradigm of the unconscious visual set and its ver-bal and nonverbal variants may provide a suitable experi-mental model for identifying the role of the ventral and dor-sal visual systems in cognitive activity in the organizationof cortical functions of visual recognition at the consciouslevel.

The phenomenon of the set can be used in psycho-physiology as an effective model for experimental studiesof one of the most interesting and difficult problems in thecerebral organization of human behavior, i.e., the role ofunconscious types of neurological-mental activity in theconscious mental activity of humans.

REFERENCES

1. P. K. Anokhin, Biology and Neurophysiology of the ConditionedReflex [in Russian], Meditsina, Moscow (1968).

2. I. S. Beritov, Neural Mechanisms of Behavior in Higher Vertebrates[in Russian], Academy of Sciences of the USSR Press, Moscow(1961).

3. I. S. Beritov, “The psychoneural bases of the set action of the exter-nal context and individual behavior,” Fiziol. Zh. SSSR, 33, No. 2,301–312 (1947).

4. L. S. Vygotskii, Collected Writings [in Russian], Volume 1:Questions of the Theory and History of Psychology, Pedagogika,Moscow (1982).

5. É. A. Kostandov, N. S. Kurova, E. A. Cheremushkin, and I. A. Yako-venko, “Relationship between the verbal set on the context of cog-nitive activity,” Zh. Vyssh. Nerv. Deyat., 50, No. 3, 43–50 (2000).

6. É. A. Kostandov, N. S. Kurova, E. A. Cheremushkin, and I. A. Yako-venko, “Relationship between the stability of the visual cognitive setand motivation,” Zh. Vyssh. Nerv. Deyat., 51, No. 3, 304–309 (2001).

7. É. A. Kostandov, N. S. Kurova, E. A. Cheremushkin, and I. A. Yako-venko, “The role of working memory in the formation of the visualset,” Zh. Vyssh. Nerv. Deyat., 52, No. 3, 149–155 (2002).

8. É. A. Kostandov, N. S. Kurova, and E. A. Cheremushkin, “Changesin cortical electrical activity during the formation of the set in con-ditions of increased loading on working memory,” Zh. Vyssh. Nerv.Deyat., 54, No. 4, 448–454 (2004).

9. É. A. Kostandov, N. S. Kurova, E. A. Cheremushkin, and I. A. Yako-venko, “Relationship between the set and the involvement of theventral and dorsal visual systems in cognitive activity,” Zh. Vyssh.Nerv. Deyat., 55, No. 2, 156–163 (2005).

10. É. A. Kostandov, E. A. Cheremushkin, and M. L. Ashkenazi, “Chara-cteristics of the visual non-verbal set in children of preschool andschool age,” Zh. Vyssh. Nerv. Deyat., in press (2005).

11. N. S. Kurova, E. A. Cheremushkin, and M. L. Ashkenazi, “EEGspectral characteristics at different stages of an unconscious visualset at two levels of motivation,” Zh. Vyssh. Nerv. Deyat., 52, No. 4,406–416 (2002).

12. P. V. Simonov, “The light spot of consciousness,” Zh. Vyssh. Nerv.Deyat., 40, No. 6, 1040–1044 (1990).

13. P. V. Simonov, The Creative Brain [in Russian], Nauka, Moscow(1993).

14. D. N. Uznadze, “The experimental bases of the psychology of theset,” in: Experimental Studies on the Psychology of the Set[in Russian], Academy of Sciences of the Georgian SSR Press,Tbilisi (1958), pp. 5–126.

15. D. A. Farber, T. G. Beteleva, A. S. Gorev, N. V. Dubrovinskaya, andR. I. Machinskaya, “Functional organization of the developing brainduring the formation of cognitive activity,” in: Physiology of ChildDevelopment [in Russian], M. M. Bezrukikh and D. A. Farber (eds.),Education from A to Z, NPO, Moscow (2000), pp. 82–103.

16. T. A. Tsekhmistrenko, V. A. Vasil’eva, and N. S. Shumeiko, “Structu-ral rearrangements of the human cerebral cortex and cerebellum dur-ing postnatal ontogenesis,” in: The Physiology of Child Development[in Russian], M. M. Bezrukikh and D. A. Farber (eds.), Educationfrom A to Z, NPO, Moscow (2000), pp. 60–81.

17. D. A. Farber and M. M. Bezrukikh, “Theoretical aspects of the studyof the physiological development of children” in: The Physiology ofChild Development [in Russian], M. M. Bezrukikh and D. A. Farber(eds.), Education from A to Z, NPO, Moscow (2000), pp. 9–13.

18. E. A. Cheremushkin and I. A. Yakovenko, “The cognitive set and thecharacteristics of personality as per Kettel,” Zh. Vyssh. Nerv. Deyat.,47, No. 6, 1048–1050 (1997).

19. R. Kharre, “The second cognitive revolution,” Psikhofiziol. Zh., 17,No. 2, 3–15 (1996).

20. J. D. Cohen, W. M. Peristein, T. S. Braver, Y. E. Nystrom, D. C. Noll,J. A. Jonides, and E. E. Smith, “Temporal dynamics of brain activa-tion during a working memory task,” Nature, 386, 604–608 (1997).

21. S. M. Courtney, Y. G. Ungerleider, K. A. Kell, and J. M. Naxby,“Transient and sustained activity in a distributed neural system forhuman working memory,” Nature, 386, 608–611 (1997).

22. G. Deco and B. Schürmann, “A neuro-cognitive visual system forobject recognition based on testing of interactive attentional top-down hypotheses,” Perception, 29, 1249–1264 (2000).

23. M. D’Esposito, Y. A. Detze, D. C. Alsop, R. K. Shin, S. A. Atlas, andM. Grossman, “The neural basis of the central executive system ofworking memory,” Nature, 378, 279–281 (1995).

24. J. W. Fockert, G. Rees, C. D. Frith, and N. Yavie, “The role of work-ing memory in visual selective attention,” Science, 291, 1803–1806(2001).

Kostandov328

25. E. Paulesi, C. D. Frith, and R. S. J. Frackowiak, “The neural corre-lates of the verbal component of working memory,” Nature, 382,342–345 (1993).

26. J. M. Fuster and G. E. Alexander, “Firing changes in cells of thenucleus medialis dorsalis associated with delayed response behav-ior,” Brain Res., 61, No. 1, 79–91 (1973).

27. P. Goldman-Rakic, “Space and time in the mental universe,” Nature,386, No. 6625, 559–560 (1997).

28. M. A. Goodale, D. A. Westwood, and A. D. Milner, “Two distinctmodes of control for object-directed action,” Progr. Brain Res., 144,131–144 (2004).

29. J. W. James, G. K. Humphrey, J. S. Gati, et al., “Differential effectsof viewpoint on object-driven activation in dorsal and ventralstreams,” Neuron, 35, No. 4, 793–801 (2002).

30. J. V. James, J. Culham, G. K. Humphrey, et al., “Ventral occipitallesions impair object recognition but not object-directed grasping:an fMRI study,” Brain, 126, No. 11, 2463–2475 (2003).

31. V. A. F. Jamme and P. R. Roolfsma, “The distinct modes of visionoffered by feedforward and recurrent processing,” Trends Neurosci.,23, 571–579 (2000).

32. S. Konishi, M. Kawazu, I. Uchida, H. Kikyo, I. Asakura, andY. Miyashita, “Contribution of working memory to transient activa-tion in human inferior prefrontal cortex during performance of theWisconsin Card Sorting Test,” Cerebral Cortex, 9, 745–753 (1999).

33. S. Konishi, K. Nakajimita, I. Uchidal, M. Makeyoma, K. Nakahaza,K. Sekihaza, and Y. Miyashita, “Transient activation of inferior pre-frontal cortex during cognitive set shifting,” Nature Neurosci., 1,No. 1, 80–84 (1999).

34. R. I. Machinskaya, Brain Organisation of Voluntary SelectiveAttention in First-Grade Children with Learning Difficulties. Neuro-

nal Basis and Psychological Aspects of Consciousness, C. Taddei-Farrettia and C. Musio (eds.), World Science, Singapore (1999),pp. 343–347.

35. R. Malach, I. A. Yevi, and U. Hasson, “The topography of high-order human object areas,” Trends Cogn. Sci., 6, No. 4, 176–184(2002).

36. V. Meron, J. M. Ford, K. O. Kim, G. N. Glover, and A. Pfefferbaum,“Combined event-related fMRI and EEG evidence for temporal-parietal cortex activation during target detection,” Neuroreport, 8,No. 14, 3129–3037 (1997).

37. M. Mishkin, Y. Ungerlieder, and K. A. Macko, “Object vision andspatial vision. Two cortical pathways,” Trends Neurosci., 6, 414–417(1983).

38. O. Monchi, M. Petrides, V. Petre, K. Worsley, and A. Dagher,“Wisconsin card sorting revisited: distinct neural circuits participat-ing in different stages of the task identified by event-related func-tional magnetic resonance imaging,” J. Neurosci., 21, No. 19,7733–7741 (2001).

39. V. R. Mountcastle, “Some neural mechanisms for directed atten-tion,” in: Cerebral Correlates of Conscious Experience, P. Buser andA. Rougeul-Buser (eds.), Elsevier, North Holland Biomedical Press,Amsterdam (1978), pp. 37–51.

40. M. I. Posner and M. E. Raichle, Images of Mind, Scientific AmericanLibrary (A division of HPHYP), New York (1997).

41. E. Paulesi, C. D. Frith, and R. S. Y. Frackowiak, “The neural corre-lates of the verbal component of working memory,” Nature, 382,342–345 (1993).

42. C. S. Revert, “Slow potential correlates of anticipation in subcortexof the monkey brain,” EEG Clin. Neurophysiol., 31, No. 3, 299(1971).

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