Characterization of discrete and continuous modes of visual pattern discrimination

Ferraro, Mario; Foster, David H.

doi:10.1007/bf00317935

Cited by 7 publications

(5 citation statements)

References 21 publications

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“…Because the results of these post hoc analyses indicating the use of qualitatively invariant or quasi-invariant properties were essentially inferential, we have undertaken experiments to test their use explicitly. In previous work, Foster (1980a; Ferraro & Foster, 1984) has suggested that binary-valued cues (also called discrete attributes ) such as collinearity determine maxima in performance in some simple tasks requiring point-discrimination (Foster, 1979), angle-discrimination (Foster, 1980b), and curved-line discrimination (Foster, 1983). Pursuing this approach, we have used a perturbation technique (Foster, 1980b) that progressively distorted pairs of same patterns, degrading each qualitatively invariant property.…”

Section: Possible Strategies or Sources Of Informationmentioning

confidence: 99%

Minimal information to determine affine shape equivalence.

Wagemans¹,

Gool²,

Troy³

et al. 2000

Journal of Experimental Psychology: Human Perception and Perfor

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Participants judged the affine equivalence of 2 simultaneously presented 4-point patterns. Performance level (d') varied between 1.5 and 2.7, depending on the information available for solving the correspondence problem (insufficient in Experiment 1a, superfluous in Experiment 1b, and minimal in Experiments 1c, 2a, 2b) and on the exposure time (unlimited in Experiments 1 and 2a and 500 ms in Experiment 2b), but it did not vary much with the complexity of the affine transformation (rotation and slant in Experiment 1 and same plus tilt in Experiment 2). Performance in Experiment 3 was lower with 3-point patterns than with 4-point patterns, whereas blocking the trials according to the affine transformation parameters had little effect. Determining affine shape equivalence with minimal-information displays is based on a fast assessment of qualitatively or quasi-invariant properties such as convexity/ concavity, parallelism, and collinearity.

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Section: Possible Strategies or Sources Of Informationmentioning

confidence: 99%

Minimal information to determine affine shape equivalence.

Wagemans¹,

Gool²,

Troy³

et al. 2000

Journal of Experimental Psychology: Human Perception and Perfor

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“…Thus, a sharply peaked discrimination performance was associated with the use of coarse discrete encodings and a smoothly varying discrimination performance was associated with the use of fine-grained continuous encodings. A theoretical rationale for this interpretation has been given elsewhere (Foster, 1980b;Ferraro and Foster, 1984). *A portion of the data presented here was contained in a paper read at the Seventh European Conference on Visual Perception, Cambridge, UK, 31 August-3 September 1984. †To whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 98%

Discrete and continuous modes of curved-line discrimination controlled by effective stimulus duration

Ferraro

Foster²

1986

Spatial Vis

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In previous experiments two extreme modes of visual discrimination performance have been investigated by measuring small differences in pattern shape at points along a continuum of pattern shapes. These two modes, associated with discrete and continuous encoding processes, were obtained by simultaneously manipulating the number of pattern components in the display and the effective duration of the display. In this experiment, discrimination performance was measured for a fixed number of pattern components, namely three, and variable display time course. The stimuli used were curved lines drawn from a continuum with curvature parameter s. There were three stimulus time courses: (1) 2-s stimulus display, (2) 100-ms stimulus display, and (3) 100-ms stimulus display followed by a post-stimulus mask. Discrimination performance declined smoothly and monotonically with s for (1), but varied non-monotonically with s revealing a central peak for (3). Performance for (2) was intermediate between that for (1) and that for (3). A reduction in effective stimulus duration alone was thus sufficient to cause a transition from continuous to discrete modes of discrimination performance, a result which may be compatible with an explanation of variable discrimination modes based on a method of successive internal approximations of the stimulus.

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“…Second, in separate measurements of curved-line discrimination in which a range of ds values was used for long- and short-duration displays, the same pattern of performance (expressed as reciprocal spatial threshold) was obtained (Foster & Cook, 1989). Some analyses of size effects of ds have been considered in Ferraro and Foster (1984).…”

Section: Discussionmentioning

confidence: 99%

“…Could the effects of reduced stimulus duration be regarded as a spatial threshold-scaling effect? That is, could the short-duration discrimination functions be brought into coincidence with the long-duration functions by scaling the parameter axis (expanding the long-duration one or contracting the short-duration one) according to some characteristic spatial threshold (see Ferraro & Foster, 1984, for related technical discussion)? Such a simple proposal is appealing, but may not suffice here, for the spatial thresholds under the two exposure conditions were not very different (and for one subject actually overlapped).…”

Section: Discussionmentioning

confidence: 99%

“…A different type of performance was obtained when the duration of the display was reduced to 100 ms and a poststimulus mask was introduced: A pronounced peak in curved-line discrimination performance was obtained about halfway along the stimulus range (and a second peak revealed in more fine-grained measurements at smaller curvatures) (Ferraro & Foster, 1986;Foster, 1983). To attempt to relate this "discrete" mode of performance (Ferraro & Foster, 1984) to the characteristics of possible internal descriptors for curvature, independent labeling experiments were also performed with a categorical-identification scale and three uniform categorical-rating scales. From these labeling data, predicted discrimination performances were computed.…”

Section: Categorical Effectsmentioning

confidence: 99%

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Visual gap and offset discrimination and its relation to categorical identification in brief line-element displays.

Foster¹,

Ferraro²

1989

Journal of Experimental Psychology: Human Perception and Perfor

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Visual processing was investigated in judgments of relative line position. Stimulus continua were generated by bisecting a straight line and displacing the segments. Experiment l measured discrimination of pairs of longitudinally displaced segments at equal steps along the continuum. At long (2 s) durations discrimination fell smoothly, but at short (100 ms) durations it was sharppeaked. In Experiment 2 the short-duration stimuli were labeled with subsets of the labels no gap, just a gap, and more than just a gap. Theoretical discrimination performances were computed and the one based on no gap and just a gap closely fitted observed performance. Experiments 3 and 4 were similar to 1 and 2, with lateral replacing longitudinal displacement. Similar "categorical" performance was obtained. It was concluded that there are discrete mechanisms for early detection of relative line position and that 2 labels can be used to characterize performance in each direction.

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Characterization of discrete and continuous modes of visual pattern discrimination

Cited by 7 publications

References 21 publications

Minimal information to determine affine shape equivalence.

Minimal information to determine affine shape equivalence.

Discrete and continuous modes of curved-line discrimination controlled by effective stimulus duration

Visual gap and offset discrimination and its relation to categorical identification in brief line-element displays.

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