Enhancing the perception of form in peripheral vision

Experiments are reported which show that the tachistoscopic presentation of a figure at the point of fixation makes salient the same figure where it occurs elsewhere in the visual field during the same flash. This induced saliency operates in all directions from the axis of gaze. If the eccentric figure is alone on a blank field the phenomenon is termed 'eccentric enhancement'. The induced saliency of figures that are laterally masked within horizontal strings of figures that lie off the fixation point is termed 'demasking'.     

The empirical basis of color perception

Rationalizing the perceptual effects of spectral stimuli has been a major challenge in vision science for at least the last 200 years. Here we review evidence that this otherwise puzzling body of phenomenology is generated by an empirical strategy of perception in which the color an observer sees is entirely determined by the probability distribution of the possible sources of the stimulus. The rationale for this strategy in color vision, as in other visual perceptual domains, is the inherent ambiguity of the real-world origins of any spectral stimulus.     

Dynamic form perception in the bending

As a white hourglass moves across a black background, the middle appears to lag behind its true position, resulting in the apparent bending of the axis of the hourglass. No such distortion occurs with a black hourglass moving across a white background. The results of two experiments support a visual persistence hypothesis, as opposed to a latency hypothesis.     

The physiological basis of transcranial magnetic stimulation

Transcranial magnetic stimulation (TMS) is the noninvasive method of choice for studying the causal relevance of a cortical area in the human brain. The success of TMS, however, is contrasted by limited insight into its mechanism of action. A recent study by Allen and colleagues offers stunning new insight into the physiological underpinnings of TMS. Their findings expand our understanding about a method that is widely used for stimulating research in the cognitive neurosciences.     

The naive perception of masculinity-femininity on the basis of expressive cues

Groups of naive judges rated 18 videotaped stimulus persons on masculinity, femininity, “dominance, assertiveness,” and “compassion, sensitivity to others.” Stimulus persons were broken down by sex and sex-typing—half were male, half female—and within sexes one third were classified as masculine, feminine, and androgynous on the basis of their scores on the Bem Sex Role Inventory. Two experiments are reported in which groups of judges rate stimulus persons on the basis of such different expressive information as videotaped pictures and recorded voices, videotaped pictures alone, videotaped bodies, videotaped heads, recorded voices, and still photos. The results showed: (1) Judges reliably rated masculinity-femininity from largely expressive cues: (2) judgments of masculinity-femininity were not predominantly determined by judgments of sex role-related traits: (3) the naive judgment of masculinity-femininity significantly corresponded to stimulus subjects' assessed sex roles; (4) stimulus subjects (particulary males) showed a consistent display of masculinity-femininity across expressive channels; and (5) judges used different expressive cues in judging masculinity-femininity in males and females. These results are related to broader questions concerning the relation between expressive behavior and personality.     

Development of three-dimensional form perception

In three experiments with infants and one with adults we explored the generality, limitations, and informational bases of early form perception. In the infant studies we used a habituation-of-looking-time procedure and the method of Kellman (1984), in which responses to three-dimensional (3-D) form were isolated by habituating 16-week-old subjects to a single object in two different axes of rotation in depth, and testing afterward for dishabituation to the same object and to a different object in a novel axis of rotation. In Experiment 1, continuous optical transformations given by moving 16-week-old observers around a stationary 3-D object specified 3-D form to infants. In Experiment 2 we found no evidence of 3-D form perception from multiple, stationary, binocular views of objects by 16- and 24-week-olds. Experiment 3A indicated that perspective transformations of the bounding contours of an object, apart from surface information, can specify form at 16 weeks. Experiment 3B provided a methodological check, showing that adult subjects could neither perceive 3-D forms from the static views of the objects in Experiment 3A nor match views of either object across different rotations by proximal stimulus similarities. The results identify continuous perspective transformations, given by object or observer movement, as the informational bases of early 3-D form perception. Detecting form in stationary views appears to be a later developmental acquisition.     

Attentional biases in geometric form perception

This paper reports the operation of robust attentional bias to the top and right during perception of small, single geometric forms. Same/different judgements of successively presented standard and comparison forms are faster when local differences are located at top and right rather than in other regions of the forms. The bias persists when form size is reduced to approximately one degree of visual angle, and it is unaffected by saccadic eye movements and by instructions to attend to other reliably differentiating regions of the forms. Results lend support in various degrees to two of the possible explanations of the bias: (1) a static, skewed distribution of attentional resources around eye fixation; and (2) biased, covert scanning that commences invariably at the top and right of stim ulus forms. Origins of the bias in terms of possible left-hemispheric capacity for constructing representations of visual stimuli from parts, as well as in terms of reading experience and prevailing optic flow during locomotion through space are considered. Recent investigations of conditions under which the bias can be maintained or reduced are mentioned.     

Age differences in peripheral letter perception

The capacities of 96 eight- and nine-year-old children and 96 adults to discriminate letters in the visual periphery were tested. Four-letter arrays were presented at the fixation point or centered 4 degrees to the left or right. Threshold exposure durations were estimated by a method of ascending limits. Analyses of a transformed threshold measure revealed that although children were less able than adults to discriminate letters in all positions, age differences were greatest for peripherally presented arrays. Development specific to the peripheral visual systems seems implicated.