Jan B. Deregowski

Description of White and Black Faces by White and Black Subjects

Abstract A previous experiment by Shepherd, Deregowski and Ellis (1974) showed that white subjects are better at remembering white faces than black faces, and that black subjects are superior at recognizing black compared with white faces. The present experiment was designed to investigate the frequencies with which white and black subjects use different facial features when describing faces. It was found that black and white subjects did differ in their descriptions of faces, which was interpreted as reflecting differences in attention to the various aspects of facial detail. The difference in attention deployment is suggested as a possible basis for the earlier reported differences in recognition memory for white and black faces by white and black subjects.

Learning to See the Impossible

Four experiments investigating childrens ability to detect the impossibility of impossible figures are reported. In the first, children were required to identify the impossible figure from a pair of corresponding possible and impossible figures. Whilst seven-year-old children were able to detect the impossibility of certain impossible figures, their overall level of performance was lower than that of older children. Regardless of age, the impossibility of some types of figure was found to be relatively easy or difficult to detect. Experiment 2 confirmed this pattern of results using a task that required children to copy possible and impossible figures from memory. Experiment 3 showed that, when the impossibility of an impossible figure is not readily detected, this is not due to failure to understand the conventions used in that figure to represent depth and solidity. In experiment 4 predictions from different hypotheses concerning the principal factor responsible for the detection of impossibility were tested. Results support the view that the detection of impossibility requires the construction of a mental representation (internal model) of the interrelationships of the constituent parts of the depicted object. It is suggested that the construction of such internal models may be of general importance in picture perception.

Teaching African Children Pictorial Depth Perception: In Search of a Method:

Data, suggesting that the exposure of pictorially relatively unsophisticated subjects to stereograms is likely to alleviate their difficulties in perception of pictorial depth in ordinary stimuli, are presented. It is suggested that this remedial measure may prove efficacious in populations that are experiencing such difficulties and are hence handicapped in their use of visual aids.

Efficacy of objects, pictures and words in a simple learning task

Abstract Adult subjects were required to memorise positions associated with twelve common objects, their pictures and their names. Both written and spoken names were used. It was found that learning was fastest with the objects and slowest with verbal symbols, and that pictures occupied an intermediate position. The data suggest that the errors observed are partly due to differential forgetting of various types of stimuli and partly perhaps to differential difficulty in making deductions from them.

A Cross-Cultural Comparison of the Use of a Gestalt Perceptual Strategy

The ability to discriminate whether pictured box shapes (parallelopipeds) are projections of three-dimensional rectangular forms has been demonstrated by Perkins and Cooper in US populations and interpreted as a symptom of a general Gestalt strategy in perception. Deregowski suggested earlier that this perceptual strategy might not appear as strongly in less ‘carpentered’ cultures, among perceivers less familiar with Western modes of depiction. A study is reported in which the performance on the discrimination by US children in grades 1, 4, and 7; and children from Zimbabwe, Africa, in grades 1, 2, 4, and 7—children of less experience with pictures and urban environments—has been examined. All groups evinced the discrimination at high levels of statistical significance. However, the findings disclosed much less accurate performance in the Zimbabwe groups at all grade levels, and no improvement with age either in the US or in Zimbabwe. The absence of improvement argues against an explanation of the difference between the US and Zimbabwe groups in terms of either a carpentered-world hypothesis or a difficulty with picture perception, at least when those interpretations are taken in their simplest forms.

On a changing perspective illusion within Vermeer's The Music Lesson.

The effect of line of sight on the perception of spatial configuration has been investigated in a well-known painting (The Music Lesson by Vermeer) and in two control patterns. In experiment 1, subjects indicated the perceived inclination of two major contours which defined the sidewall—floor and backwall—floor joints in (i) a projected image of the painting, (ii) a three-line representation of the major spatial elements of the painting, and (iii) a three-dimensional wire model of these same contours, when standing in each of eighteen positions on a line running parallel to the surface of the screen. Results indicated a significant change in the perception of the sidewall—floor, but not of the backwall—floor contour, as viewing angle changed, in both the painting and the three-line representation. However, the angular setting in the latter case was significantly less than when the painting was used, ie subjects underestimated the depicted inclination. Settings for the wire model did not deviate with viewing angle and reflected geometrically correct adjustments. In experiment 2, the results of experiment 1 were confirmed using enantiomorphs. These findings are discussed in the light of other view-dependent illusions in paintings.

A Study of Orientation Errors in Response to Kohs-Type Figures

Abstract In order to elucidate the nature of the orientation errors encountered when subjects are required to reproduce Kohs-type figures, subjects drawn from a culture where such errors are reported to be relatively common were required to reproduce orientation of simple figures. It was found that the responses made in the case of square figures showed a definite drift towards a “stable” orientation; the drift observed in the case of circular stimuli was too weak to permit an unambiguous interpretation. The relevance of these data to previous data on cross-cultural differences in responses to Kohs-type stimuli is briefly examined.

Coding and Drawing of Simple Geometric Stimuli by Bukusu Schoolchildren in Kenya

Bukusu schoolboys were asked to draw a cube and a tetrahedron, the stimulus being either in a form of a skeleton solid or its picture. Two response conditions were used: in one, subjects drew the drawing with model present; in the other, they drew after it had been removed from sight. No significant difference was observed between the responses made to the model, whether from recall or with model present. This finding also applied to drawings of a tetrahedron but not to drawings of a cube which, when time lapse between inspection and drawing was allowed, evoked responses similar to those evoked by the model. Drawings made without such a lapse of time differed significantly from those made in response to respective models.

“Principle of economy” and perception of pictorial depth: A cross‐cultural comparison

Abstract Two experiments were conducted to ascertain whether the “principle of economy” can be applied to perception of the third dimension in simple geometric diagrams, and whether such principle could be said to apply cross-culturally. Support for application of the principle was found in the case of one of the two sets of stimuli used. Cross-cultural investigation involving Ivorean and Scottish school children did not show cross-cultural differences in applicability of the principle.

Construction errors as a key to perceptual difficulties encountered in reading technical drawings

A large number of subjects drawn from a variety of populations was required to build simple models in response to diagrams. Their responses were evaluated with especial reference to the errors made. It seems that the errors were largely due to misperception of the drawings and therefore show what difficulties people are likely to find when required to use technical drawings. These difficulties range from inability to perceive elementary units correctly (a weakness characteristic of the least educated/sophisticated subjects) to inability to group the relations among such units. Examples of errors made are discussed and their significance for training in the usage of technical drawings stressed.