In a paradigm for which 2 distinct patterns are perceived for the same stimulus, perceptual hysteresis (persistence of a percept despite parameter change to values favoring the alternative pattern) and temporal stability (persistence despite intrinsic propensities toward spontaneous change) are interdependent. Greater persistence during parameter change reduces temporal stability, slowing the rate of parameter change reduces hysteresis by increasing opportunity for spontaneous change, and increasing temporal stability (by enlarging the stimulus) increases hysteresis. Hysteresis results in the perception of parametrically disfavored patterns; a parameter can influence a percept without specifying it. The visual system thus exhibits time-dependent behavior analogous to dynamical behavior observed in other systems, both physical and biological, for which there is competition among alternative patterns that vary in relative stability.

Perceptual decisions are often affected not only by the evidence gathered during a trial but also by the history of preceding trials. This effect—termed perceptual hysteresis—provides evidence for how perceptual information is represented and how it is used. The present research focuses on how the difficulty of preceding trials affects subsequent ones—we find that how well 5-year-old children perform in a 2-alternative forced-choice numerical discrimination task depends on whether they have had a prior history of easier discriminations or a prior history of harder discriminations. Furthermore, this effect is modulated by the feedback children receive. In 3 experiments, we demonstrate that these effects are not related to practice or loss of interest due to negative feedback, or simply to trial difficulty or discriminability. Instead, children appear to have state-dependent confidence states such that prolonged experience making low-confidence decisions degrades performance, whereas prolonged experience making high-confidence decisions improves it. These results are discussed in the context of dynamical psychophysics, representations of confidence, and work on children’s and adults’ number perception abilities.

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Previous studies have indicated that the formation of coherent patterns for multielement motion displays depends on global cooperative interactions among large ensembles of spatially distributed motion detectors. These interactions enhance certain motion directions and suppress others. It is reported here that perceiving one element moving between two nearby locations likewise is subject to cooperative influences (possibly facilitating and inhibiting interactions within a local ensemble of overlapping detectors). Thresholds depending on luminance contrast were measured for a generalized singleelement apparent-motion stimulus, and evidence for spontaneous switching and hysteresis effects indicated that motion perception near the 50% threshold was bistable. That is, for conditions in which motion and nonmotion were perceived half the time, the two percepts were distinct; when one was perceived, it clearly was discriminable from the other. These results indicated that (1) single-element apparent-motion thresholds depended on the immediately preceding state of the ensemble of motion detectors responding to the stimulus, and (2) the stimulus activation of individual motion detectors always might be influenced by recurrent, cooperative interactions resulting from the detectors' being embedded within interconnected ensembles.Previous studies have indicated that the formation of coherent patterns for multielement motion displays depends on global cooperative interactions among ensembles of spatially distributed motion detectors that enhance certain motion directions and suppress others. Chang and Julesz (1983) and Williams and Sekuler (1984) have shown that all the dots in a random cinematogram appear to move coherently when a limited number ofmotion directions are stimulated consistently by a relatively small percentage of the moving elements, and Petersik (1990) has demonstrated that motion perceived in one part of a random cinematogram can increase the likelihood of motion being perceived in a neighboring part of the cinematogram. Nawrot and Sekuler (1990) and Hock and Balz (1994) have provided evidence that, depending on the distance, global spatial interactions can either facilitate or inhibit the perception of motion in a particular direction.In this article, we report the results of experiments involving the perception of single-element apparent motion over small spatial displacements. When motion is not perceived, two stationary elements are perceived instead (the perception of nonmotion was sometimes, but not always, accompanied by the perception of flicker). The key finding is that the motion perceived for singleelement apparent motion is like the perception of globalWe are grateful to Gregor Schaner, Kathleen Eastman, Martin Giese, and three anonymous reviewers for their careful reading of an earlier version of the manuscript and their valuable suggestions. Correspondence and requests for materials should be sent to H. Hock, Department of Psychology, Florida Atlantic University, Boca Raton, FL 33431 (e-mail: ...

It was hypothesized that performance in the same-different comparison task is based on two modes of processing: (I) structural processes that organize the detailed parts of a stimulus into a well-formed whole, and (2) analytic processes that decompose the stimulus into features. This hypothesis was supported, but with the unexpected finding of individual differences in the mode of processing underlying "same" responses. Those Ss in the "same" condition whose reaction times were faster for symmetrical than for asymmetrical patterns supported the hypothesis for structural processes. The remaining Ss in the "same" condition, as well as all the Ss in the "different" condition, were unaffected by symmetry. These Ss supported the hypothesis for analytic processes. Although familiarity effects were obtained for both structural and analytic Ss, the rotation of the familiar patterns into an unfamiliar orientation virtually eliminated familiarity effects for the structural Ss, bu t left them intact for analytic Ss.