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Results for “FORM PERCEPTION”

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PubMed1989

Emergent features, attention, and perceptual glue in visual form perception.

We examined the grouping of line segments into unitary shapes and attempted to identify procedures to diagnose when such grouping is taking place. Previous research has indicated that attentional measures may diagnose grouping: With grouped parts, selective attention to individual parts is difficult and divided attention across parts is easy, whereas with ungrouped parts selective attention is easy and divided attention is difficult. This result suggests that grouping operates via a perceptual glue binding parts into wholes that are difficult or impossible to divide. Other studies have suggested in addition that grouped parts produce emergent features, possibly including symmetry and closure, that make possible configural superiority effects, where whole shapes are more discriminable than are their distinguishing contours shown in isolation. The 13 experiments reported here indicate that perceptual glue is not needed to explain known findings about grouping, a claim that agrees with conclusions by other investigators using other criteria. Rather, emergent features alone may suffice to explain grouping, provided that reliable and accurate diagnostic criteria can be identified. It is shown that the diagnostics now available are not fully adequate for this purpose. Surprisingly, it appears that some prime candidates for emergent features--namely, closure and line terminators--may not be of central importance to form perception.

Adult↗
PubMed2000

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 stimulus 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.

Adult↗