Visual spatial perception and paternal deprivation

College men and women who were father deprived for at least 1 year from birth to 18 years of age or non-deprived were compared on the Spatial Relations Test of the Differential Aptitude Tests (DAT), the Identical Blocks Test (IBT) and the Water Level Test (WLT). There was a significant sex difference favoring men—as expected—on the IBT and WLT but not on the DAT. There was no significant effect of father deprivation on the mean performance on any test but there was a correlation between years of deprivation and WLT performance for men (r = 0.48,P < 0.001). No other correlation between deprivation and test performance was significant.     

Facilitation of learning spatial relations among locations by visual cues: generality across spatial configurations

Spatial pattern learning permits the learning of the location of objects in space relative to each other without reference to discrete visual landmarks or environmental geometry. In the present experiment, we investigated conditions that facilitate spatial pattern learning. Specifically, human participants searched in a real environment or interactive 3-D computer-generated virtual environment open-field search task for four hidden goal locations arranged in a diamond configuration located in a 5 × 5 matrix of raised bins. Participants were randomly assigned to one of three groups: Pattern Only, Landmark + Pattern, or Cues + Pattern. All participants experienced a Training phase followed by a Testing phase. Visual cues were coincident with the goal locations during Training only in the Cues + Pattern group whereas a single visual cue at a non-goal location maintained a consistent spatial relationship with the goal locations during Training only in the Landmark + Pattern group. All groups were then tested in the absence of visual cues. Results in both environments indicated that participants in all three groups learned the spatial configuration of goal locations. The presence of the visual cues during Training facilitated acquisition of the task for the Landmark + Pattern and Cues + Pattern groups compared to the Pattern Only group. During Testing the Landmark + Pattern and Cues + Pattern groups did not differ when their respective visual cues were removed. Furthermore, during Testing the performance of these two groups was superior to the Pattern Only group. Results generalize prior research to a different configuration of spatial locations, isolate spatial pattern learning as the process facilitated by visual cues, and indicate that the facilitation of learning spatial relations among locations by visual cues does not require coincident visual cues.     

Visual recognition memory for complex configurations

Previous studies of recognition memory for heterogeneous pictorial stimuli suggest an unusually large storage and retrieval capacity. In the first experiment, three series of homogeneous pictures (faces, ink blots, snow crystals) were presented to six independent groups of Ss, and recognition was tested immediately or 48 h later. Accuracy and sex were related to stimulus configuration; at both time intervals, accuracy was best for faces and poorest for snow crystals. Levels of accuracy were below those attained in studies using heterogeneous arrays. The results of two other experiments suggest the relative unimportance of verbal mediation in recognition of homogeneous pictorial stimuli.     

Visual form discrimination: Multidimensional analyses

Nonmetric multidimensional scaling techniques were used to evaluate discrimination latency as a similarity measure. A three dimensional Euclidian solution was found for a sample of random polygons. The dimensions were labeled compactness, jaggedness, and elongation. The spatial configuration was highly similar to results obtained from similarity estimates and the dimensions were systematically related to physical shape measures.     

Visual perception of collinearity

In a metrical space, there exists an intimate relation between collinearity and parallelity. In particular, in a Riemannian space collinearity is just a special case of parallelity. Is this true for visual space as well? We investigated the visual perception of collinearity by having subjects align two bars in the horizontal plane at eye height. The distances of the bars from the subject and the angles at which they were placed were varied. We found deviations of up to 22 degrees. The deviations of the left and right bars could be split into two independent components: namely, the sum and the difference of the deviations of the left and right bars. We found that the former depended only on the ratio between the distances of each bar from the subject, whereas the latter was largely independent of the positions of the bars. The difference in deviations corresponded to the deviation from parallelity. Compared with the results in the parallelity task (Cuijpers, Kappers, & Koenderink, 2000b), the deviations from parallel were much smaller. As a consequence, the results of the two experiments cannot be described by the same Riemannian geometry. This indicates that the intrinsic geometry of visual space differs across tasks. This is conceivable if the intrinsic geometry of visual space is operationally defined.     

Visual perception of markings

Markings, such as designs, writings, diagrams, and depictions, are expressive and communicative human artifacts. The conventional assumption that findings from the study of the visual perception of markings—in particular, of pictures—can be generalized to real-world perception is examined and found to be false. The processes involved in the visual perception of the world and in the visual perception of markings differ in significant ways, and generalizations from one to the other must be undertaken with caution. The visual perception of markings is an identifiable and separate area of study. Implications for a general theory of the perception of markings are examined, and the perception of markings is contrasted with real-world perception.     

Action influences spatial perception: Neuropsychological evidence

We present neuropsychological evidence indicating that action influences spatial perception. First, we review evidence indicating that actions using a tool can modulate unilateral visual neglect and extinction, where patients are unaware of stimuli presented on one side of space. We show that, at least for some patients, modulation comes about through a combination of visual and motor cueing of attention to the affected side (Experiment 1). Subsequently, we review evidence that action‐relations between stimuli reduce visual extinction; there is less extinction when stimuli fall in the correct colocations for action relative to when they fall in the incorrect relations for action and relative to when stimuli are just associatively related. Finally, we demonstrate that action relations between stimuli can also influence the binding of objects to space, in a patient with Balint's syndrome (Experiment 2). These neuropsychological data indicate that perception–action couplings can be crucial to our conscious representation of space.     

Visual and tactual texture perception: Intersensory cooperation

In three experiments, subjects were required to make texture judgments about abrasive surfaces. Touch and vision provided comparable levels of performance when observers attempted to select the smoothest of three surfaces, but bimodal visual and tactual input led to greater accuracy. The superiority of bimodal perception was ascribed to visual guidance of tactual exploration. The elimination of visual texture cues did not impair bimodal performance if vision of hand movements were permitted. It is suggested that touch may preempt vision when both sources of texture information are simultaneously available. The results support the notion that perception is normally multimodal, since restriction of the observer to either sense in isolation produces lower levels of performance.     

Visual space perception and action: Introductory remarks

Vision evolved from the vital necessity to act in a dynamic environment. Following this view it is clear that perceptual processes and action planning are much more interlocked than is evident at first sight. This is especially evident in visual space perception; actions are performed in space and are guided and controlled by objects in spatial positions. Here we shortly introduce the three research camps dealing with the relationship between space perception and action: the ecological camp, the two‐visual‐systems camp, and the constructivist camp. We show that these camps emphasize and open different theoretical and empirical perspectives, but that they can be seen to complement each other. We end with an overview of the papers in this special issue.     

Visual working memory contaminates perception

Indirect evidence suggests that the contents of visual working memory may be maintained within sensory areas early in the visual hierarchy. We tested this possibility using a well-studied motion repulsion phenomenon in which perception of one direction of motion is distorted when another direction of motion is viewed simultaneously. We found that observers misperceived the actual direction of motion of a single motion stimulus if, while viewing that stimulus, they were holding a different motion direction in visual working memory. Control experiments showed that none of a variety of alternative explanations could account for this repulsion effect induced by working memory. Our findings provide compelling evidence that visual working memory representations directly interact with the same neural mechanisms as those involved in processing basic sensory events.     

Visual perception of surface wrinkles

To study the relationship between visual perception of magnitude of wrinkles and geometrical parameters of surfaces, four potentially relevant parameters of the surface profile were considered: the variance (sigma2), the cutting frequency (Fc), the effective disparity curvature (Dce) of the wrinkled surface over the eyeball distance of the observer, and the frequency component of the disparity curvature (Dcf). Analysis of garment seams with varying amount of pucker showed that, while the logarithm for each of these four parameters has a strong linear relationship with the visually perceived magnitude of wrinkles, following the Fechner Law, the effective disparity curvature (Dce) and the frequency component of the disparity curvature (Dcf) with visual perception appeared stronger. This modeling may be an objective method for measuring magnitude of surface wrinkles.     

Visual perception in 'low vision'

'Low vision' has an international classification as an impairment of vision that is defined by loss of visual acuity and the size of the visual field. Functional classification that would depict capability to use vision in different activities has not yet been agreed upon. Abnormal visual information leads to changes in visual perception, and brain-damage-related visual impairment may alter or prevent one or several cognitive visual functions. Abnormal visual perception opens a window into brain mechanisms that the psychophysicists otherwise do not have. Together with clinicians, psychophysicists can help visually impaired persons to understand the nature of their disability by thoroughly studying the nature of the altered image and the profile of cognitive visual functions.     

Visual perception and aging.

A series of studies performed in our laboratory on aging and its effect on perceptual processing and working memory capacity for visual stimuli are reviewed. Specifically, studies on luminance, colour, motion, texture, and symmetry processing are reported. Furthermore, experiments on the capacity to retain size and spatial frequency information are also discussed. The general conclusion is that there are a number of perceptual abilities that diminish with age. However, the extent of these deficits will depend on the complexity of the neural circuitry involved for processing a given task. This is also true for visual working memory where no evidence of loss due to aging is demonstrated for processing low-level visual information, when individual differences in sensory input are compensated for. It is concluded that perceptual processing deficits due to aging (like working memory) will become evident when the computational load reaches a certain level of complexity (larger or more complex network) even if the tasks remain cognitively simple.     

Visual factors in word perception

An experiment is reported confirming the existence of the “word-letter phenomenon” (WLP): At tachistoscopic exposure durations, each letter of a four-letter word is perceived more accurately than a single letter. Data obtained rule out several artifactual interpretations, including the possibility that perception of letters in a word is facilitated merely by the presence of adjacent contours. The WLP is shown to depend critically on what type of display is used as a preand postexposure field. While a masking field of high-contrast random contours produced a large and reliable WLP, a plain white field eliminated the phenomenon entirely. This pattern of results suggests several ways in which perception at the word level may differ from perception at the letter level.     

Visual perception and corollary discharge

Perception depends not only on sensory input but also on the state of the brain receiving that input. A classic example is perception of a stable visual world in spite of the saccadic eye movements that shift the images on the retina. A long-standing hypothesis is that the brain compensates for the disruption of visual input by using advance knowledge of the impending saccade, an internally generated corollary discharge. One possible neuronal mechanism for this compensation has been previously identified in parietal and frontal cortex of monkeys, but the origin of the necessary corollary discharge remained unknown. Here, we consider recent experiments that identified a pathway for a corollary discharge for saccades that extends from the superior colliculus in the midbrain to the frontal eye fields in the cerebral cortex with a relay in the medial dorsal nucleus of the thalamus. We first review the nature of the evidence used to identify a corollary discharge signal in the complexity of the primate brain and show its use for guiding a rapid sequence of eye movements. We then consider two experiments that show this same corollary signal may provide the input to the frontal cortex neurons that alters their activity with saccades in ways that could compensate for the displacements in the visual input produced by saccadic eye movements. The first experiment shows that the corollary discharge signal is spatially and temporally appropriate to produce the alterations in the frontal-cortex neurons. The second shows that this signal is necessary for this alteration because inactivation of the corollary reduces the compensation by frontal-cortex neurons. The identification of this relatively simple circuit specifies the organization of a corollary discharge in the primate brain for the first time and provides a specific example upon which consideration of the roles of corollary activity in other systems and for other functions can be evaluated.