How the intentions of the draftsman shape perception of a drawing

The interaction between the recovery of the artist’s intentions and the perception of an artwork is a classic topic for philosophy and history of art. It also frequently, albeit sometimes implicitly, comes up in everyday thought and conversation about art and artworks. Since recent work in cognitive science can help us understand how we perceive and understand the intentions of others, this discipline could fruitfully participate in a multidisciplinary investigation of the role of intention recovery in art perception. The method I propose is to look for cases where recovery of the artist’s intentions interacts with perception of a work of art, and this cannot be explain by a simple top-down influence of conscious propositional knowledge on perception. I will focus on drawing and show that recovery of the draftsman’s intentional actions is handled by a psychological process shaped by the motor system of the observer.     

Emotional intelligence and social perception

One of the key facets of emotional intelligence (EI) is the capacity of an individual to recognise emotions in others. However, this has not been tested cross-culturally, despite the body of research indicating that people are better at recognising facial affect of members of their own culture. Given the emotion recognition aspect of EI, it would seem that EI should be related to correctly identifying emotion in others regardless of race. In order to test this, a social perception inspection time task was carried out in which participants (41 Caucasian and 46 Far-East Asian) were required to identify the emotion on Caucasian and Far-East Asian faces that were happy, sad, or angry. Results from this study indicate that EI was not related to correctly identifying facial expressions. The results did confirm that participants are better able to recognise people of their own ethnicity, though this was only applicable to negative emotions.     

Functional equivalence of masking and cue reduction in perception of shape at a slant

The present study was undertaken to investigate the effects of syllabic stress and segment structure on selective adaptation in speech. To this end, a CV place of articulation test continuum was selectively adapted by seven different adapting stimuli; the monosyllables [ba] and [ga], two disyllabic stimuli containing equal stress on both syllables, [baga] and [gabal, and three disyllabic stimuli ([baga]) in which stress placement varied and was cued by the acoustic parameters of fundamental frequency and duration. Results for the two adapting stimuli demonstrated significant [b] adaptation for the stimulus [ba] and significant [g] adaptation for [gal. Of the five other adapting stimuli, only [g] adaptation for the stimulus [bagá] was found to be significant. These findings indicate that the operation of detector mechanisms susceptible to fatigue by an adapting stimulus are even more constrained than has heretofore been suggested. It appears that the adapting and test stimuli must not only have the same phonetic and syllable structure, but also the same syllabic organization.     

Anisotropy in haptic curvature and shape perception

An investigation was undertaken into whether haptic comparison of curvature and of shape is influenced by the length/width ratio of the hand. For this purpose three experiments were conducted to test the curvature matching of curved strips (experiment 1), the curvature matching of cylindrically curved hand-sized surfaces (experiment 2), and the shape discrimination of elliptically curved hand-sized surfaces (experiment 3). The orientation of the stimuli with respect to the fingers was varied. The results of the two matching experiments showed that a given curvature is judged to be more curved when touched along the fingers than when touched across the fingers. The phenomenal flatness along and across the fingers was found to be different and subject dependent. The results of the shape-discrimination experiment showed that the orientation of ellipsoidal surfaces influences the judgments of the shapes of these surfaces. This influence could be predicted on the basis of results of the second matching experiment. It is concluded that similar mechanisms underlie the (anisotropic) perception of curvature and shape. For the major part the trends in the results can be explained by the length/width ratio of the hand and the phenomenal flatnesses.     

On the perception of shape from shading

The extraction of three-dimensional shape from shading is one of the most perceptually compelling, yet poorly understood, aspects of visual perception. In this paper, we report several new experiments on the manner in which the perception of shape from shading interacts with other visual processes such as perceptual grouping, preattentive search (“pop-out”), and motion perception. Our specific findings are as follows: (1) The extraction of shape from shading information incorporates at least two “assumptions” or constraints—first,that there is a single light source illuminating the whole scene, and second, that the light is shining from “above” in relation to retinal coordinates. (2) Tokens defined by shading can serve as a basis for perceptual grouping and segregation. (3) Reaction time for detecting a single convex shape does not increase with the number of items in the display. This “pop-out” effect must be based on shading rather than on differences in luminance polarity, since neither left-right differences nor step changes in luminance resulted in pop-out. (4) When the subjects were experienced, there were no search asymmetries for convex as opposed to concave tokens, but when the subjects were naive, cavities were much easier to detect than convex shapes. (5) The extraction of shape from shading can also provide an input to motion perception. And finally, (6) the assumption of “overhead illumination” that leads to perceptual grouping depends primarily on retinal rather than on “phenomenal” or gravitational coordinates. Taken collectively, these findings imply that the extraction of shape from shading is an “early” visual process that occurs prior to perceptual grouping, motion perception, and vestibular (as well as “cognitive”) correction for head tilt. Hence, there may be neural elements very early in visual processing that are specialized for the extraction of shape from shading.     

Symmetry in haptic and in visual shape perception

Four experiments tested the hypothesis that bilateral symmetry is an incidental encoding property in vision, but can also be elicited as an incidental effect in touch, provided that sufficient spatial reference information is available initially for haptic inputs to be organized spatially. Experiment 1 showed that symmetry facilitated processing in vision, even though the task required judgments of stimulus closure rather than the detection of symmetry. The same task and stimuli failed to show symmetry effects in tactual scanning by one finger (Experiment 2). Experiment 3 found facilitating effects for vertically symmetric open stimuli, although not for closed patterns, in two-forefinger exploration when the fore-fingers had previously been aligned to the body midaxis to provide body-centered spatial reference. The one-finger exploration condition again failed to show symmetry effects. Experiment 4 replicated the facilitating effects of symmetry for open symmetric shapes in tactual exploration by the two (previously aligned) forefingers. Closed shapes again showed no effect. Spatial-reference information, finger movements, and stimulus factors in shape perception by touch are discussed.     

Further studies in the perception of a changing shape

Koffka's hypothesis of “invariant relation” holding between tilt and perceived shape of an object is discussed from the standpoints both of logical tenability and of experimental findings.

After discussion of certain shortcomings in the method of investigation devised by Stavrianos, two experiments are suggested, the first, of a simple character, intended to follow out in practice the hypothetical conclusions of Koffka's argument, the second to test the hypothesis under conditions which attempt to ensure the preservation of the perceptual object throughout the arc of tilt. For this purpose subjects attempt to match two shapes, one of which is stationary whilst the other revolves at a constant speed. The comparison shapes cover the range of the possible arc of tilt.

The results of the first experiment, whilst appearing to contradict the requirements of the hypothesis, are by no means conclusive. The second experiment, though not absolutely conclusive, gives little support to Koffka. The main conclusion drawn is that there occur non-systematic variations in perceptual constancy throughout the arc of tilt. These are of a phasic character and are qualitatively different from results obtained by matching stationary shapes. There appears to be no simple function which would result in exhibiting a uniform constancy value for the entire arc of orientation.     

Light source position in the perception of object shape

The apparent relief of monocularly viewed surfaces reversed when the order of light and shade was reversed relative to the position of a lamp observed the moment earlier. The pattern of shading was reversed either by illuminating from a direction opposite to that of the apparent direction of illumination or by inverting the illuminating image relative to the light source. The combination of both of these manipulations restores the original juxtaposition of light source and shading and reestablished accurate perception of relief. These results demonstrate that the perception of the relief of physical surfaces depends upon the remembered position of an apparent light source.     

Personality profiles at various levels of athletic participation

Various grades of athletes (265 male and 134 female) were administered the German version of the EPQ. The entire group was characterized by being more extraverted and less neurotic (compared to population norms); sex differences were exhibited, female profiles being higher on emotionality and lower on Psychoticism (tough-mindedness) with no significant difference being observed in mean Extraversion scores. When grouped in terms of ‘level of competitive involvement’, top-class male athletes were shown to be significantly more tough-minded and less stable than middle- or lower-class participants, an almost opposite trend being found in females, where top athletes were liable to be more extraverted, less neurotic and less aggressive and tough-minded than the other classes.     

The perception of a rotating shape

A regularly rotated shape was matched to given shapes set in the frontal parallel plane position, under conditions which yielded practically zero constancy. It was found that increases in the rate of rotation resulted in increases in the angular settings at which the subjects matched the rotating shape to the given standard shapes. Thus Langdon's (1951) experimental results were confirmed. However, since matches to the “real” shape also increased with increases in the rate of rotation, Langdon's interpretation of his experimental results is considered to be incorrect. Further theoretical discussion is advanced in support of this conclusion: namely, that regular rotation of a shape, viewed under conditions which usually yield zero constancy, does not restore constancy.     

The perception of a changing shape

Under specified conditions a pair of simple shapes are matched by a subject when almost all supplementary textural and space cues of depth vision have been removed. Under such conditions it is found that shape constancy is no longer present. However, the effect of regular rotatory motion of the shape is sufficient to restore constancy in the continued absence of other cues. Degree of perceptual constancy appears to be correlated with rate of change of shape. It is suggested that an explanation of the phenomenon is to be sought along the lines of Michotte's concept of “object creation” rather than in terms of gradient variables.     

On the perception of shape from shading.

The extraction of three-dimensional shape from shading is one of the most perceptually compelling, yet poorly understood, aspects of visual perception. In this paper, we report several new experiments on the manner in which the perception of shape from shading interacts with other visual processes such as perceptual grouping, preattentive search ("pop-out"), and motion perception. Our specific findings are as follows: (1) The extraction of shape from shading information incorporates at least two "assumptions" or constraints--first, that there is a single light source illuminating the whole scene, and second, that the light is shining from "above" in relation to retinal coordinates. (2) Tokens defined by shading can serve as a basis for perceptual grouping and segregation. (3) Reaction time for detecting a single convex shape does not increase with the number of items in the display. This "pop-out" effect must be based on shading rather than on differences in luminance polarity, since neither left-right differences nor step changes in luminance resulted in pop-out. (4) When the subjects were experienced, there were no search asymmetries for convex as opposed to concave tokens, but when the subjects were naive, cavities were much easier to detect than convex shapes. (5) The extraction of shape from shading can also provide an input to motion perception. And finally, (6) the assumption of "overhead illumination" that leads to perceptual grouping depends primarily on retinal rather than on "phenomenal" or gravitational coordinates. Taken collectively, these findings imply that the extraction of shape from shading is an "early" visual process that occurs prior to perceptual grouping, motion perception, and vestibular (as well as "cognitive") correction for head tilt. Hence, there may be neural elements very early in visual processing that are specialized for the extraction of shape from shading.     

Fechner, information, and shape perception

How do retinal images lead to perceived environmental objects? Vision involves a series of spatial and material transformations—from environmental objects to retinal images, to neurophysiological patterns, and finally to perceptual experience and action. A rationale for understanding functional relations among these physically different systems occurred to Gustav Fechner: Differences in sensation correspond to differences in physical stimulation. The concept of information is similar: Relationships in one system may correspond to, and thus represent, those in another. Criteria for identifying and evaluating information include (a)?resolution, or the precision of correspondence; (b)?uncertainty about which input (output) produced a given output (input); and (c)?invariance, or the preservation of correspondence under transformations of input and output. We apply this framework to psychophysical evidence to identify visual information for perceiving surfaces. The elementary spatial structure shared by objects and images is the second-order differential structure of local surface shape. Experiments have shown that human vision is directly sensitive to this higher-order spatial information from interimage disparities (stereopsis and motion parallax), boundary contours, texture, shading, and combined variables. Psychophysical evidence contradicts other common ideas about retinal information for spatial vision and object perception.     

The time course of perception and retrieval in matching and recognition

A four-part experiment was carried out to study the relationship between the time course of object-feature perception and the time course of retrieval of object information from memory. The experiment consisted of 2 perceptual matching tasks, and 2 perceptual recognition tasks. In all 4 tasks, participants provided speeded judgments of the identity of 2 objects. A stochastic feature-sampling model was used to estimate the time needed for feature perception and the time needed for retrieval of feature information. No evidence was found for a systematic relationship between perception times and retrieval times for individual features. Indeed, the model applications indicated that retrieval times were constant for different features, whereas perception rates varied across the features.     

Development of the perception of invariants: substance and shape

Three experiments investigated the perception of substance and shape as invariant properties of objects by three-month-old infants. In experiment 1, infants were habituated to two differently shaped objects undergoing a rigid motion. After habituation of the infants, the objects were presented undergoing a different rigid motion, or undergoing a deforming motion, or undergoing the same rigid motion. Habituation was maintained to the new rigid motion, indicating that the two rigid motions were perceived as sharing an invariant property. Dishabituation, on the other hand, occurred when a deforming motion followed a rigid one. In experiment 2, infants were habituated to one shape undergoing two different rigid motions. After habituation, the shape was changed but the same two motions continued. Dishabituation occurred, compared to a group with no shape change, indicating that shape is distinguished as an invariant property over two rigid motions. In experiment 3, habituation to a shape undergoing two rigid motions was followed by a new shape presented motionless, or the same shape presented motionless. Cessation of motion did not prevent recognition of shape as invariant. Two properties of an object, substance and shape, thus appear to be detectable as invariant in an event sequence, an instance of "phenomenal doubling" at an early age.     

Common mechanisms in apparent motion perception and visual pattern matching

There are close functional similarities between apparent motion perception and visual pattern matching. In particular, striking functional similarities have been demonstrated between perception of rigid objects in apparent motion and purely mental transformations of visual size and orientation used in comparisons of objects with respect to shape but regardless of size and orientation. In both cases, psychophysical data suggest that differences in visual size are resolved as differences in depth, such that transformation of size is done by translation in depth. Furthermore, the process of perceived or imagined translation appears to be stepwise additive such that a translation over a long distance consists of a sequence of smaller translations, the durations of these steps being additive. Both perceived and imagined rotation also appear to be stepwise additive, and combined transformations of size and orientation appear to be done by alternation of small steps of pure translation and small steps of pure rotation. The functional similarities suggest that common mechanisms underlie perception of apparent motion and purely mental transformations. In line with this suggestion, functional brain imaging has isolated neural structures in motion area MT used in mental transformation of size.