The repetition discrimination task: An objective method for studying perceptual grouping

Stephen E. Palmer; Diane M. Beck

doi:10.3758/bf03194454

EXPRESS: Competition between perceptual grouping cues in an indirect objective task

Quarterly Journal of Experimental Psychology ◽

10.1177/17470218211010486 ◽

2021 ◽

pp. 174702182110104

Author(s):

Cristina Villalba-Garcia ◽

Mikel Jimenez ◽

Dolores Luna Blanco ◽

José Antonio Hinojosa ◽

Pedro R. Montoro

Keyword(s):

Perceptual Grouping ◽

Discrimination Task ◽

Indirect Method ◽

Reaction Times ◽

Main Task ◽

Common Region ◽

Vision Science ◽

Visuomotor System ◽

Gestalt Grouping ◽

The Individual

The integration between Gestalt grouping cues has been a relatively unexplored issue in vision science. The present work introduces an objective indirect method based on the repetition discrimination task to determine the rules that govern the dominance dynamics of the competition between both intrinsic (Experiment 1: proximity vs. luminance similarity) and extrinsic grouping cues (Experiment 2: common region vs. connectedness) by means of objective measures of grouping (reaction times and accuracy). Prior to the main task, a novel objective equating task was introduced with the aim of equating the grouping strength of the cues for the visuomotor system. The main task included two single conditions with the grouping cues acting alone as well as two competing conditions displaying the grouping factors pitted against one another. Conventional aggregated analyses were combined with individual analysis and both revealed a consistent pattern of processing dominance of: (1) luminance similarity over proximity, and of (2) common region over connectedness. Interestingly, the individual analyses showed that, despite the heterogeneous responses to the single conditions, the pattern of dominance between cues was robustly homogenous among the participants in the competing conditions.

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Convex Grouping Impedes Detection of Stereoscopic Depth

Perception ◽

10.1068/v970142 ◽

1997 ◽

Vol 26 (1_suppl) ◽

pp. 242-242

Author(s):

Z Liu

Keyword(s):

Perceptual Grouping ◽

Image Plane ◽

Stereoscopic Depth ◽

Relative Depth ◽

Objective Method ◽

Good Continuation ◽

Depth Discrimination ◽

Ground Segmentation ◽

Planar Regions ◽

Oval Shape

When two image regions are separated by an occluder, the strength of their perceptual grouping behind the occluder depends in part on the possible smoothness of the hidden contour completions (ie, Gestalt ‘good continuation’). We consider if grouping strength also depends on whether the contour completion is convex or concave. We hypothesised that the stronger the grouping between two such regions, the harder it is to resolve their relative stereoscopic depth; and employed accordingly an objective method of relative depth discrimination. The stimulus was in stereo. A horizontal bar in the centre of the image occluded two pairs of planar regions parallel with the image plane. One pair assumed a convex (oval) shape behind the occluder, the other pair a concave (hourglass) shape. The regions in one pair had a slight depth difference. The task was to detect which pair was not coplanar. The convex grouping impeded detection of stereoscopic relative depth (73% vs 86%, F1,10=8.66, p < 0.02). This held even when the convex completion boundaries were less smooth than the concave ones, a result opposite to predictions by Gestalt ‘good continuation’. In a control experiment, the stimulus was viewed with the ‘occluder’ in the background, so grouping was no longer possible. No difference between the two pairs was found. Our results suggest that convexity, known to play a role in figure/ground segmentation, is also significant in perceptual grouping, and can even win out over ‘good continuation’. We also propose an objective method of depth discrimination to study perceptual grouping in general.

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Disappearance Voltage Determinations Using a Convergent Beam

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064979 ◽

1971 ◽

Vol 29 ◽

pp. 184-185

Author(s):

W. L. Bell

Keyword(s):

Second Order ◽

Objective Method ◽

Uniform Thickness ◽

Rocking Curve ◽

Crystal Perfection ◽

Kikuchi Line ◽

Central Maximum ◽

Diffraction Patterns ◽

Convergent Beam ◽

Beam Technique

Disappearance voltages for second order reflections can be determined experimentally in a variety of ways. The more subjective methods, such as Kikuchi line disappearance and bend contour imaging, involve comparing a series of diffraction patterns or micrographs taken at intervals throughout the disappearance range and selecting that voltage which gives the strongest disappearance effect. The estimated accuracies of these methods are both to within 10 kV, or about 2-4%, of the true disappearance voltage, which is quite sufficient for using these voltages in further calculations. However, it is the necessity of determining this information by comparisons of exposed plates rather than while operating the microscope that detracts from the immediate usefulness of these methods if there is reason to perform experiments at an unknown disappearance voltage.The convergent beam technique for determining the disappearance voltage has been found to be a highly objective method when it is applicable, i.e. when reasonable crystal perfection exists and an area of uniform thickness can be found. The criterion for determining this voltage is that the central maximum disappear from the rocking curve for the second order spot.

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Stimulus Ratio Effects on Speech Discrimination by Children and Adults

Journal of Speech Language and Hearing Research ◽

10.1044/jshr.3403.671 ◽

1991 ◽

Vol 34 (3) ◽

pp. 671-678 ◽

Cited By ~ 9

Author(s):

Joan E. Sussman

Keyword(s):

Discrimination Task ◽

Response Pattern ◽

Response Patterns ◽

Speech Discrimination ◽

Adult Group ◽

Discrimination Accuracy ◽

Formant Frequency ◽

Response Strategies ◽

Place Of Articulation ◽

Adults And Children

This investigation examined the response strategies and discrimination accuracy of adults and children aged 5–10 as the ratio of same to different trials was varied across three conditions of a “change/no-change” discrimination task. The conditions varied as follows: (a) a ratio of one-third same to two-thirds different trials (33% same), (b) an equal ratio of same to different trials (50% same), and (c) a ratio of two-thirds same to one-third different trials (67% same). Stimuli were synthetic consonant-vowel syllables that changed along a place of articulation dimension by formant frequency transition. Results showed that all subjects changed their response strategies depending on the ratio of same-to-different trials. The most lax response pattern was observed for the 50% same condition, and the most conservative pattern was observed for the 67% same condition. Adult response patterns were most conservative across condition. Differences in discrimination accuracy as measured by P(C) were found, with the largest difference in the 5- to 6-year-old group and the smallest change in the adult group. These findings suggest that children’s response strategies, like those of adults, can be manipulated by changing the ratio of same-to-different trials. Furthermore, interpretation of sensitivity measures must be referenced to task variables such as the ratio of same-to-different trials.

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