Mental rotation of tactual stimuli

Acta Psychologica 73 (1990) 245-257

North-Holland 245

MENTAL ROTATION OF TACTUAL STIMULI *

Anna DELLANTONIO and Filippo SPAGNOLO

University of Pndua, Italy

Accepted June 1989

Three experiments involving different angular orientations of tactual shapes were performed. In

experiment 1 subjects were timed as they made ‘same-different’ judgments about two successive

rotated shapes. Results showed that no rotation effect is obtained, i.e., reaction times and error percentages do not increase linearly with rotation angle. The same negative results were found in

experiment 2, in which subjects were similarly timed while they made mirror-image discrimina-

tions. In experiment 3 a single-stimulus paradigm was used and subjects were asked to decide if a

rotated stimulus was a ‘normal’ or ‘reversed’ version. Reaction times increased linearly with

angular departure from the vertical. Therefore, for tactual stimuli too, this study confirms previous results, which suggest that a mental rotation strategy only occurs if it is facilitated by

both type of task and type of stimulus. Results also show a significant difference between hands,

and between hands and type of response. Implied hemispheric differences are discussed.

Introduction

Reaction times (RTs) for visual judgments of sameness or difference are known to be longer if the stimulus figure is rotated with respect to the target. In Shepard and Metzler’s (1971) work, two three-dimensional figures were presented and subjects were asked to decide whether the pair was the same or different. RTs for ‘same’ judgments increased linearly as a function of angular departure between the orientations of the two figures, suggesting a mental rotation process: subjects mentally rotated one figure into congruence with the other before making their judgments.

* This research was supported by 60% contributions from the Italian MPI.

Many thanks are due to S. Bettella for computer programming, U. Toffano for technical assistance and Gabriel Walton for revision of the English text, and to the referees for their

valuable criticism.

Requests for reprints should be sent to A. Dellantonio. Universita degli Studi di Padova, Via 8 Febbraio 2, 35122 Padua, Italy.

Elsevier Science Publishers B.V. (North-Holland)

246 A. Delhmmo, F. Spagnolo / Mentd rot&on of’tnctual strmuli

The first purpose of our research was to test whether this is the case when the figures to be matched are tactually explored. The use of tactual stimuli in rotation tasks has yielded opposing results. Warm and Foulke (1968) reported data which showed a lack of spatial orientation effects on RTs recorded for correct scores, and O’Connor and Hermelin (1975) maintained ‘ the apparent rotation independence of touch compared with sight’.

In a different research context Heller (1980, 1981) failed to show the effect of orientation on symbol recognition when letters or numbers were drawn on the palm of the hand, although later (1986) he showed that tactual reading is very poor if orientation varies, even if it is announced before each trial. Conversely, in a sameedifferent tactual judgment task, Marmor and Zaback (1976) found that RTs for the sighted, adventitiously blind and congenitally blind increase as a linear function of angular disparity between stimuli. These results suggest that, since both sighted and blind subjects show orientation effects, they use a rotation strategy which does not depend on visual imagery. Carpenter and Eisenberg (1978) obtained similar results and concluded that mental rotation may operate on spatial representation without specifically visual components. On the basis of these data, it may be hypothesized that the absence of rotation effects in the results of Warm and Foulke (1968), O’Connor and Hermelin (1975) and Heller (1980, 1981) does not depend on the fact that the task is tactual, but on the strategy subjects use to carry it out. A rotated image may be identified on the basis of its salient characteristics (in this case, the comparison between rotated images is in any case slower and more difficult than that between non-rotated images) or by means of a holistic strategy (imaginary rotation) which makes RTs vary linearly with variation in rotation angle. In previous literature, results indicative of mental rotation were obtained when subjects adopted a holistic strategy, as in mirror-image discriminations (Cooper 1975; Cochran et al. 1983). When stimuli are compared on the basis of individual features, as in the same-different judgment task, subjects do not afwu_ys seem to be induced to use strategies involving mental rotation (see Corballis and McLaren (1984) for an analytical discussion).

The second aim of our experiments was to clarify the relationship between internal representation of tactual shapes and the different performance of each cerebral hemisphere, using rotated and non-rotated figures. Right hemisphere specialization for spatial tasks is well-known

A. Dellantonio, F. Spagnolo / Menial rotation of tactual stimuli 247

(for a review, see De Renzi 1982), and left visual field (LVF) superiority for alphanumeric characters (Cohen 1975) and non-verbal stimuli (Corballis and McLaren 1984) presented in different orientations has already been reported, reflecting the specialization of the right hemisphere in mental rotation tasks. Ratcliff (1979) reported results with the same significance on tests carried out by subjects with cerebral damage: right-brain damaged subjects performed worse than left-damaged ones on controls on mental rotation tasks. Although not all results agree on this point (Le Doux et al. 1977), in the context of researches on transformation of visual mental images Kosslyn (1987) has recently rehypothesized that the right hemisphere is specialized in rotation operations for internal representations too. For this reason, it seemed pertinent to gather data on the relationships between the right hemisphere and mental rotation of tactual stimuli.

Experiment 1

Experiment 1 was merely preliminary and designed to test whether, in a simple task of same-different comparison of rotated tactual stimuli, (i) RTs increase in proportion with increasing angle of rotation of the stimulus figure with respect to the target, (ii) left-hand (right-hemisphere) performance is better than right-hand (left-hemisphere) performance.

Method

Procedure Two same or different tactual shapes were presented one after the other. The second

shape (test stimulus) was rotated in the plane around its baricentre with respect to the first shape (target stimulus) and s,ubjects were asked to give a ‘same’ or ‘different’ judgment to the second shape. There were three shapes (see fig. l), formed with pin heads following the procedure of Warm and Foulke (1968). Vertical and horizontal spacing between the centers of adjacent pin heads was 4 mm; dot diameter was 1.5 mm.

A B C

. . . . . . . . . . . ..* . . . . . . . . . . . . . . . .

Fig. 1. Stimuli A, B and C (see text for description).

248 A. Dellantonio. F. Spagnolo / Mental rotation of tactual stmulr

b c I

bip bip bip

bip

Fig. 2. Sequence of each trial in experiments 1 and 2. a: index finger explores test stimulus for 4

set; b: finger is raised; c: stimulus is changed at interstimuli intervals of 2 set; d: double beep

indicates that finger must explore target and timer starts; finger explores stimulus and presses it, thus stopping timer (see Method in text).

These stimuli were displayed on two small trays in a partially enclosed box, placed

on a table between subject and experimenter. In each trial the subjects, who could not

see the shapes, slipped their right or left hand into the box. The experimenter touched

that hand and the subject first explored the target stimulus with the index finger of the

touched hand for 4 set, then the test stimulus as soon as a computerized beep was

heard. An electric millisecond counter started at the beginning of the test signal and

stopped when the subject pressed the test stimulus after having explored it. The test

stimulus was placed on a tray directly connected to the computer (see later). The

interstimulus interval was 2 set, and response times and errors were recorded by the

computer for each, subject. The sequence of stimulus presentation is shown in fig. 2.

On every trial and for each pair of shapes (AB, BC, CA, AA, BB, etc.) the first

shape was always presented in the same position (O”, base downwards and distinctive

outline upwards), while the second shape was randomly presented at 0 O, 60”. 120 O,

180”, 240 o or 300 O. The three possible Same pairs were presented twice in the six

orientations, in order to obtain 36 Same trials. For the 36 Different trials, three

combinations were presented twice (AB, BC, CA) in the six different orientations to

half the subjects and the reverse combinations (BA, CB, AC) to the other half. Half the

trials were carried out asking subjects to use the left index finger and half with the right

index finger. Half the subjects responded Same by pressing the test stimulus once and

Different by pressing it twice; the other half responded using the reverse arrangement.

The timer stopped at the first press and recorded the time used; an automatic control

circuit registered Same responses after the first press and Different responses after the

second press, annulling them if they occurred more than 2 set after the first press. If

subjects made errors or if their response latencies exceeded an arbitrarily set global

limit of 6 set, these trials were discarded but not replaced. A computerized mechanism

was used to check false judgments.

The stimulus pairs were presented in a completely random sequence: hand (left,

right) x type or response (Same, Different) x orientation (O-300 o in 60 o steps). Writ-

ten instructions requested subjects to respond as quickly and accurately as possible: no

feedback was given. The experimental sessions lasted about 50 min and began after

practice trials during which subjects familiarized themselves with the stimuli and

A. Dellantonio, F. Spagnolo / Mental rotation of tactual stimuli 249

learned to press the keyboard in the ‘same’ or ‘different situations, in different conditions of stimulus orientation.

Subjects

Subjects were 16 male university students between the ages of 19 and 26 (mean age 23 years), all right-handed according to Oldfield’s (1971) Handedness Inventory; none had left-handed parents.

The same selection criteria for handedness were also followed in experiments 2 and 3.

Results

The analysis of variance carried out on percentages of errors (E) transformed into arcsin (Winer 1971) showed a significant type of response effect, F(1, 15) = 12.478, p -C 0.05: Different responses were more accurate than Same responses (32% vs. 45%). Moreover, the orientation effect, F(5, 75) = 3.388, p < 0.01, and the interaction type of response x orientation, F(5, 75) = 2.611, p i 0.05, were significant. Post-hoc compari- sons showed a significant difference (p < 0.05) for Same responses between orientations of 0 o and 120 O, 180 o and 240 O; no difference was found for Different responses (see fig. 3).

A within-subjects analysis of variance was carried out for correct RTs (median values of all analyses, in experiments 2 and 3 too) on three factors: hand (left, right), type of response (same, different), and orientation (0 O, 60 O, 120 O, 180 O, 240 O, 300 o ) and showed the following significant values: main orientation effect, F(5, 75) = 12.641, p < 0.001; type of response x orientation, F(5, 75) = 9.98, p < 0.001.

All other sources of variability gave F > 1. Tukey’s post-hoc analysis (Winer 1971) on the interaction type of response x orientation (fig. 3) showed that, for Same responses, RTs at O” were significantly shorter (p < 0.01) than those at all other orientations; RTs at 60’ were significantly longer than those at 180°. No statistical significance was found for Different responses.

On the whole, in the Same responses, the orientation effect on RTs and Es concerned only the difference between orientation at 0” and all other orientations,

1 I I 0” 60” 1200 lao" 240* 3od 0” 60” 120° wo” & 300”

~~~IENTATI~~~ Fig. 3. Trend of results of experiment 1. RTs expressed in set (median values), errors in percent of

responses (ERR).

250 A. Deilmtonro. F. Spagnolo / Mentul rotatwn of tactuul strmulr

while the RTs of the Different responses did not show significant variations. Thus. no linear rotation effect was found either for the Same or for the Different trials. However, the task is more difficult for Same than for Different responses. Same responses also tended to be slower, except for condition 0”. in which the situation is reversed. Subjects’ introspective reports reflected the experimental data and help to explain them. The majority stated that they had tried to find the distinctive features of the test stimulus: if feature-analysis was positive, then subjects responded ‘Same’; if negative, they responded ‘Different’. When the stimulus was rotated, subjects reported the same difficulty. These results therefore do not agree with a mental rotation process, as found in the results of Warm and Foulke (1968) and O’Connor and Hermelin (1975). Our data also suggest that a holistic strategy is not used spontaneously and uniformly, as was found in similar visual tasks, according to Corballis and McLaren

(1984). Our interpretation may also explain the absence of differences between right- and

left-hand scores. Lastly, an analysis of variance with a between-subjects variable was carried out. The

stimulus effect (A vs. B vs. C) was not significant (F z 1). The types of stimuli did not interact significantly with any other factor. (The same analysis was also repeated for the stimuli of experiments _ 7 and 3 and the same negative results were obtained.)

Experiment 2

Experiment 2 was designed to determine whether similar results are obtained when a mental rotation strategy is used, by presenting symmetrical or asymmetrical tactual shapes rotated horizontally or vertically, as suggested by Cooper and Shepard (1973). In experiment 2 the stimuli had to be recognized as Same when they were rotated on the horizontal plane and Different when turned over.

Method

Procedure Four stimuli ~ A and B of experiment 1 and two mirror-images of A and B (formed

in the same way) - were presented in four orientations (0 O, 60 ‘. 120 O. 180 o ), clockwise for half the subjects and counterclockwise for the other half. The word ‘rotation’ was not used in the instructions. Subjects were asked to establish as quickly and accurately as possible whether the test stimulus was the ‘same’ or ‘reversed’. regardless of irs orientation. In each trial the first (target) stimulus was always presented at O”, while the second (test) stimulus could assume different orientations. The experimental set-up and procedure were identical to those of experiment 1. The four pairs (two Same and two Reversed) were presented four times for a total of 64 trials in a completely random hand X type of response X orientation sequence.

Formal testing began after a warm-up during which subjects learned to recognize the Same-Reversed versions of the stimuli and to press the keyboard in response to Same or Reversed (mirror-image) stimuli.


Subjects

Sixteen male students between 18 and 26 (mean age 24 years), all right-handed.

None had taken part in experiment 1.

Results

A three-way within-subjects analysis of variance was carried out on percentages of

errors (E) (arcsin). The three factors were hand (left, right), type of response (same,

reversed), and orientation (O”, 60”. 120°, 180° ). The main effects of type of response

and orientation were significant, F(1, 15) = 16.879. p < 0.001 and F(3, 45) = 17.333,

p -C 0.001, respectively. Same responses were more accurate than Reversed ones (21%

vs. 46%). No other sources reached statistical significance. The Tukey-A procedure

showed that responses at 0” were significantly more accurate ( p < 0.01) than those at

all other angles; the 60°-180” difference (31% vs. 48%) was also significant (fig. 4).

The within-subjects analysis of variance carried out for RTs on the same three

factors showed that the main effects of type of response and orientation were

significant, F(1, 15) = 16.45, p < 0.001 and F(3, 45) = 16.91, p i 0.001, respectively.

Same responses were faster than the Reversed ones, and RTs were significantly faster

( p c 0.01) at 0 o than at other orientations (fig. 4).

Moreover, the interaction type of response X orientation was significant, F(3,

45) = 8.78, p < 0.001, and the RTs of the Same responses were significantly different at

0 O, as opposed to 60 O, 120 o and 180 O, and of the Reversed responses not significantly

different at any orientation (fig. 4). The F ratio for the main effect of hand tended

towards significance, F(1, 15) = 4.3, p < 0.054) showing faster RTs for left than for

right hand (3,825 vs. 4,312 msec).

In one important aspect, the results of experiment 2 were similar to those of

experiment 1, in that neither RTs nor Es for Same or Reversed responses were linearly

affected by the factor orientation, suggesting that a mental rotation strategy is not

directly connected with mirror-image discriminations. One possible reason for this may

be the high level of difficulty of the trials, both for Same and Reversed responses, with

the exception of Same responses at 0”: in this condition the requested comparison

60

40s d

B 20

3

ANGULAR ORIENTATION

Fig. 4. Trend of results of experiment 2. RTs expressed in set (median values), errors in percent of responses (ERR).

252 A. Dellantonio, F. Spngnolo / Mental rotation of tuctuol stimulr

regarded two shapes which were identical in form and orientation, so that responses were faster because of the Same effect (Bamber 1969; Bagnara et al. 1985). Even the estimated difference between hands did not turn out to be relevant, probably owing to the length of time involved on the task. The task of encoding, maintaining and retrieving tactual stimulus representations probably induced subjects to isolate critical features that did not vary with respect to the angular orientation: consequently, it seemed that, as long as the shape was salient in the matching task, subjects’ strategy contrasted with the mental rotation interpretation. Accordingly, experiment 3 was designed to reduce the influence of feature-analysis in tactual mirror-image discriminations.

Experiment 3

The main aim of experiment 3 was to induce subjects to adopt a holistic strategy of mental rotation in a tactual ‘normal-reflected’ judgment task. As in Carpenter and Eisenberg (1978). subjects were presented before the trial with a single shape to be remembered. Then, this shape was presented at various orientations between 0” and 180°. Subjects were asked to determine whether it was the same or a mirror-image (reflected). We believe that this paradigm has the advantage of directing subjects’ attention towards the orientation of the shape. As only one shape (Same or Reversed) was presented throughout one trial, it was reasonable to expect that comparison between its internal representation and the steady mental representation of the target essentially depended on its orientation.

Again, a secondary concern in this experiment was to clarify the role played by both cerebral hemispheres in a mental rotation task.

Method

Procedure

The stimuli were identical to those of experiment 2 and were presented at four orientations (0”, 60°. 120°, 180° ), clockwise from the vertical for half the subjects and counterclockwise for the other half.

Subjects were tested in one 50-min session divided into two blocks: 48 trials with stimulus A only, and 48 with stimulus B only. Subjects therefore knew the identity of the stimulus before each experimental block and were timed while they haptically explored each shape. Subjects were asked to determine whether the shape was the same or the reflected (mirror-image) version, regardless of its orientation and as quickly and accurately as possible. The order of presentation of the two blocks was balanced across subjects. Subjects started to inspect the stimulus when they heard a computerized beep (point d in fig. 2). An electric millisecond counter started at the beginning of this acoustic signal and stopped when subjects pressed the keyboard (see method in experiment 1).

There were 48 Same and 48 Reflected responses, half explored using the left and the other half using the right index finger. Stimuli were presented in a random hand X type of response X orientation sequence.

A. Dehntonio, F. Spagnolo / Mental rotation of tnctual stimuli 253

Subjects

Sixteen male university students between 19 and 25 (mean age 23 years), all right-handed. None had taken part in experiments 1 or 2.

Results

The mean percentage of errors (E) was 13%; only three subjects made 27% errors. A three-way within-subjects analysis of variance (hand X type of response X orientation) on the Es (arcsin) yielded a significant main effect for orientation, F(3, 45) = 8.702,

p < 0.001. Post-hoc analysis using the Tukey-A procedure showed ( p < 0.01) that responses at

0 o were more accurate than those at 120 o and 180 O, and responses at 60 o and 120 o were more accurate than those at 180” (5%, 8%, 14% and 24% respectively). No other factor approached significance. Errors in Same responses occurred in 11% of the trials and in 14% of the Reflected responses. Performance level in this task far exceeded chance expectations, and the RT scores for correct responses were more consistent in each experimental condition and for each subject.

A three-way within-subjects analysis of variance on correct RTs yielded significant effects for orientation and hand, F(3, 45) = 15.91, p < 0.001, and F(1, 15) = 18.14, p < 0.001, respectively.

The Tukey-A procedure indicated (p < 0.05) that the RTs for upright shapes (0” ) were significantly shorter than those for shapes at 60 O, 120 o and 180 O. Moreover, RTs at 60 o differed significantly from those at 120° and 180”. The differences between 120 o and 180 o were considerable, although not significant. This suggests that subjects mentally rotated an internal representation of each shape to an appropriate vertical position before making the Same-Reflected discrimination: differences in latency did occur between 60 o (and/or 120° ) and 180 o rather than between only 0 o and the other orientations: 13 out of 16 subjects showed this pattern of results. The F ratio on RTs to test linear trend (Winer 1971) was significant, F(1, 45) = 49.48, p < 0.001, and

.

ANGULAR OFtlENTATlON

Fig. 5. Experiment 3: RTs (in set) for left (full dots) and right (empty dots) hands as a function of angular orientation of shape from the vertical. Equation for best-fitting straight line is y = 0.49x

+ 2.1.

254 A. Dellantonio, F. Spagnolo / Mental rotation of tuctual .rtrmulr

- rtght hand

t -- left hand

5

2

54 L I l

*_____----______a

Fig. 6. Experiment 3: trend of results for left and right hands as a function of type of response

(same, refl.)

accounted for about 98% of the variance. The residual 2% was not significant and the estimate of the mental rotation rate was approximately 120 “/sec.

As regards the hand effect, the left hand was significantly faster (about 0.5 set) than the right (3,656 vs. 4,225 msec); 14 subjects showed this pattern of response times. However, the interaction hand X orientation was not significant: left-hand RTs were faster than right-hand RTs across all orientations (fig. 5), although there was a significant interaction between hand and type of response, F(1, 15) = 5.542, p < 0.05 (fig. 6). The Tukey-A procedure showed that right-hand RTs were longer in Reflected than in Same responses (4,390 vs. 4,060 msec) while left-hand RTs were practically identical (3,638 vs. 3,684) and, in both cases, lower than those for the right hand. No other source of variability reached statistical significance.

Discussion

The results of experiment 3 suggest that, in order to compare one

tactually presented stimulus with its internal representation, a mental

rotation strategy is used. The orientation functions plotted in fig. 5

resemble those reported in visual studies of mental rotation.

There is an increase of about 1.5 set in latency from 0” to 180 O, and

the speed of mental rotation (120 O/set) is slower than other estimates

reported with nonsense shapes. This is probably due to the greater

complexity of the shapes we used. The structural characteristics of our

pin-figures may have made it more difficult to define the internal axis

of orientation and, as Cooper and Shepard (1973) claimed, ‘in order to

preserve the essential structure of the object’s shape, they (subjects) could carry out this imagined rotation at no faster than a certain

limiting rate’. In the experiments of Marmor and Zaback (1976) and

Cooper (1975), two plexiglass shapes and eight random nonsense


shapes, generated by Atteneave’s Method I, were presented. In both cases, subjective directional cues could be assigned to each shape, with or without practice. Obviously, for a well-known shape such as a familiar letter, identification of the conventional upright orientation is far more immediate, as in the experiments of Carpenter and Eisenberg (1978) in which latencies increased by about 0.5 set from 0” to 180” rotation.

Moreover, in experiment 3, as in experiments 1 and 2, subjects did not seem to represent the haptic shapes visually. They all stated that they had generated some representation of the pin-figures during the experiment, but not as they saw them with their own eyes after the experiment. It is interesting to examine these introspective reports. Most subjects stated that they often mentally rotated certain features, e.g., the right or left ‘L’ of shapes A and B respectively. Other subjects reported using a logical strategy: for example, when exploring shape A at 180” they first located its base and distinctive outline and then found that the ‘L’ on the left was really on the right. Three subjects did not mention mental rotation at all.

These results show that, in haptic tasks, subjects code salient features into a spatial representation containing their relative positions, but do not always translate this code into a visual representation (Carpenter and Eisenberg 1978; Marmor and Zaback 1976). Mental rotation may operate more efficiently on visual representation, with a consequently faster mental rotation rate when the stimuli are schematic or visually experienced. When spatial representation is not visual and stimuli are complex and only tactually experienced, the mental rotation rate is slower.

The second aim of the present research was to investigate the hemispheric differences in mental rotation tasks. In previous studies with tactual stimuli (Warm and Foulke 1968; O’Connor and Hermelin 1971; Marmor and Zaback 1976; Carpenter and Eisenberg 1978), the hand factor was not studied. Instead, our subjects were asked to explore tactual shapes and to make their responses with the same hand. In experiment 3, left-hand RTs were significantly shorter than right- hand ones, producing a constant advantage across all orientations. These results are in accordance with the view that the right cerebral hemisphere (RH), directly connected with the left hand, is specialized for spatial tasks and nonsense stimuli (e.g., Cohen 1975; De Renzi 1982). However, although it can also carry out orientation operations

256 A. Dellmtonro, F. Spagnolo / Mental rotntmn oftmtuul stimuli

faster than the left hemisphere (LH), the RH-LH difference is constant even when the angular distance between oriented and vertical positions is increased. This means that the LH is also influenced by orientation effects in task-solving, although it operates more slowly.

The lesser efficiency of the right hand (LH) is also revealed in experiment 3 by the fact that the right-hand RTs for Reflected responses were considerably longer (330 msec) than those for right-hand (LH) Same responses, whereas no left-hand (RH) differences were found (fig. 6). It should be recalled that, in experiment 1, subjects were asked to decide if a rotated shape was the same or different with respect to the target, and that no significant left-hand (RH) superiority was found, This pattern of results agrees with those of other authors. Simion et al. (1980) did not find a left visual field (RH) effect in a same-different classification task, while Corballis and McLaren (1984) Bradshaw et al. (1976) and Taylor (1972) found RH superiority with reflected visual patterns.

Our data confirm that both cerebral hemispheres can presumably process variously oriented tactual stimuli. However, in mirror-image discriminations, which imply the use of a more holistic strategy, the RH is more efficient at spatial orientation processing, while in same- different classifications which imply feature-by-feature analysis, the LH is more efficient at analytical processing. The lack of superiority of the LH in experiment 1 was probably due to the difficulty of the rotation task, which interfered with the sameedifferent task, and on the nature of the tactual nonsense stimuli.

More generally, the present research first confirms that, in tactual tasks, a mental rotation strategy depends on task demands, as observed in visual presentations (Eley 1982; Cochran et al. 1983). Second, mental rotation is a spatial operation that does not specifically require visual representation, and both cerebral hemispheres are probably involved in different ways.

References

Bagnara, S., F. Simian and C. Umiltk, 1985. ‘Perch6 si fa prima di dire “uguale”‘. In: W. Gerbino (ed.), Conoscenza e struttura. Bologna: I1 Mulino.

Bamber, D., 1969. Reaction times and errors for same-different judgements of multidimensional

stimuli. Perception and Psychophysics 6, 169-174.


Bradshaw, J., D. Bradley and K. Patterson, 1976. The perception and identification of mirror-re-

versed patterns. Quarterly Journal of Experimental Psychology 28, 221-246.

Carpenter, P.A. and P. Eisenberg, 1978. Mental rotation and the frame of reference in blind and

sighted individuals. Perception and Psychophysics 23, 117-124.

Cochran, E.L., A.D. Pick and H.L. Pick, 1983. Task-specific strategies of mental ‘rotation’ of

facial representations. Memory and Cognition 11, 41-48.

Cohen, G., 1975. ‘Hemispheric differences in the utilization of advanced information’. In: P M.A.

Rabbitt and S. Dornic (eds.), Attention and performance, V. London: Academic Press.

Cooper, L.A., 1975. Mental rotation of random two-dimensional shapes. Cognitive Psychology 7,

20-43.

Cooper, L.A. and R.N. Shepard, 1973. ‘Chronometric studies of the rotation of mental images’.

In: W.G. Chase (cd.), Visual information processing. New York: Academic Press.

Corballis, M.C. and R. McLaren, 1984. Minding one’s Ps and Qs: Mental rotation and mirror-

image discrimination. Journal of Experimental Psychology: Human Perception and Perfor-

mance 2, 318-327.

De Renzi, E., 1982. Disorders of space exploration and cognition. New York: Wiley.

Eley, M.G., 1982. Identifying rotated letter-like symbols. Memory and Cognition 10, 25-32.

Heller, M.A., 1980. Tactile retention: Reading with the skin. Perception and Psychophysics 27,

125-130.

Heller, M.A., 1981. Orientation and tactile symbol recognition. Perceptual and Motor Skills 53,

394-399.

Heller, M.A., 1986. Central and peripheral influences on tactual reading. Perception and Psycho-

physics 39, 197-204.

Kosslyn, S.M., 1987. Seeing and imagery in the cerebral hemispheres: A computational approach. Psychological Review 94, 148-175.

Le Doux, J.E., D.H. Wilson and M.S. Gazzaniga, 1977. A divided mind: Observations on the

conscious properties of the separated hemispheres. Annals of Neurology 2, 417-421.

Marmor, G.S. and L.A. Zaback, 1976. Mental rotation by the blind: Does mental rotation depend

on visual imagery? Journal of Experimental Psychology: Human Perception and Performance

2, 515-521.

O’Connor, N. and B. Hermelin, 1975. Modality-specific spatial coordinates. Perception and Psychophysics 17, 213-216.

Oldfield, R.O., 1971. The assessment and analysis of handedness: The Edinburgh inventory.

Neuropsychologia 9, 97-117.

Ratcliff, G., 1979. Spatial thought, mental rotation and the right hemisphere. Neuropsychologia 17.49-54.

Shepard, R.N. and J. Metzler, 1971. Mental rotation of three-dimensional objects. Science 171, 701-703.

Simion, F., S. Bagnara, P. Bisiacchi, S. Roncato and C. Umilta, 1980. Laterality effects, levels of

processing and stimulus properties. Journal of Experimental Psychology: Human Perception

and Performance 6, 184-195.

Taylor, R.L., 1972. Reading spatially transformed digits. Journal of Experimental Psychology 96, 396-399.

Warm, J.S. and E. Foulke, 1968. Effects of orientation and redundancy on tactual perception of form. Perceptual and Motor Skills 27, 83-89.

Winer, B.J., 1971. Statistical principles in experimental design. New York: McGraw-Hill.

Documents

Mental rotation of tactual stimuli