Abstract

The Gestalt psychologists reported a set of laws describing how vision groups elements to recognize objects. The Gestalt laws “prescribe for us what we are to recognize ‘as one thing’” (Köhler, 1920). Were they right? Does object recognition involve grouping? Tests of the laws of grouping have been favourable, but mostly assessed only detection, not identification, of the compound object. The grouping of elements seen in the detection experiments with lattices and “snakes in the grass” is compelling, but falls far short of the vivid everyday experience of recognizing a familiar, meaningful, named thing, which mediates the ordinary identification of an object. Thus, after nearly a century, there is hardly any evidence that grouping plays a role in ordinary object recognition. To assess grouping in object recognition, we made letters out of grating patches and measured threshold contrast for identifying these letters in visual noise as a function of perturbation of grating orientation, phase, and offset. We define a new measure, “wiggle”, to characterize the degree to which these various perturbations violate the Gestalt law of good continuation. We find that efficiency for letter identification is inversely proportional to wiggle and is wholly determined by wiggle, independent of how the wiggle was produced. Thus the effects of three different kinds of shape perturbation on letter identifiability are predicted by a single measure of goodness of continuation. This shows that letter identification obeys the Gestalt law of good continuation and may be the first confirmation of the original Gestalt claim that object recognition involves grouping.

Highlights

  • The effects of three different kinds of shape perturbation on letter identifiability are predicted by a single measure of goodness of continuation. This shows that letter identification obeys the Gestalt law of good continuation and may be the first confirmation of the original Gestalt claim that object recognition involves grouping

  • It is traditional for psychophysics papers to have a lot of data on few observers, which may seem strange to colleagues from other branches of psychology

  • Our experiments show that wiggle, a measure of sinusoidal curvature, characterizes the effect of good continuation on letter identification, independent of the kind of perturbation

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Summary

Introduction

The effects of three different kinds of shape perturbation on letter identifiability are predicted by a single measure of goodness of continuation This shows that letter identification obeys the Gestalt law of good continuation and may be the first confirmation of the original Gestalt claim that object recognition involves grouping. Noah Raizman and Chris Christian participated as undergraduates, and Edward Kim as a high-school student. Edward Kim, as a student at Stuyvesant High School, measured thresholds in our lab for snake letters as a function of spacing for his Intel National Talent Search Project, “What makes a letter?” Supported by National Eye Institute Grant R01-EY04432 to Denis Pelli. Edward Kim is at Stuyvesant High School, New York, NY, USA. We present experiments showing that grouping (good continuation) contributes to object recognition (identifying a letter). This may be the first evidence that grouping contributes to object recognition

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