Simultaneous visual detection and identification: theory and data

Thomas, James P.; Gille, Jennifer; Barker, Richard A.

doi:10.1364/josa.72.001642

Cited by 60 publications

(45 citation statements)

References 13 publications

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“…For detection, on the other hand, it is not necessary to know which channel responded, only that there was activity in some channel. Threshold detection and identification may also be based on different decision processes (Thomas, 1985;Thomas, Gille, & Barker, 1982). The results of Experiments I and 2 indicate that both hemispheres operate on equivalent bases of sensory information and apply the same detection rules.…”

Section: Resultsmentioning

confidence: 91%

Hemispheric differences are found in the identification, but not the detection, of low versus high spatial frequencies

Kitterle

Christman

Hellige

1990

Perception & Psychophysics

154

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The processing of sine-wave gratings presented to the left and right visual fields was examined in four experiments. Subjects were required either to detect the presence of a grating (Experiments 1 and 2) or to identify the spatial frequency of a grating (Experiments 3 and 4). Orthogonally to this, the stimuli were presented either at threshold levels of contrast (Experiments 1 and 3) or at suprathreshold levels (Experiments 2 and 4). Visual field and spatial frequency interacted when the task required identification of spatial frequency, but not when it required only stimulus detection. Regardless of contrast level (threshold, suprathreshold), high-frequency gratings were identified more readily in the right visual field (left hemisphere), whereas low-frequency gratings showed no visual field difference (Experiment 3) or were identified more readily in the left visual field (right hemisphere) (Experiment 4). Thus, hemispheric asymmetries in the processing of spatial frequencies depend on the task. These results support Sergent's (1982) spatial frequency hypothesis, but only when the computational demands of the task exceed those required for the simple detection of the stimuli.Perceptual characteristics of input, as well as cognitive characteristics of task, have been shown (by, e.g., Sergent & Hellige, 1986) to influence obtained patterns of cerebral asymmetry. Sergent (1982Sergent ( , 1983 proposed that the right visual field/left hemisphere (RVF/LH) is specialized for the perceptual processing of higher spatial frequencies, and that the left visual field/right hemisphere (LVF /RH) is specialized for the processing of lower spatial frequencies. Two general strategies, one involving complex stimuli and the other, simple stimuli, have been employed in testing this hypothesis, and each strategy will be discussed below in turn. Strategy 1: Complex StimuliFirst, some researchers have used complex stimuli (e.g., alphanumeric characters, faces) and have varied input characteristics (e.g., size, eccentricity, luminance, exposure duration) in order to vary the proportion of high and low frequencies in the input. When Christman (1989) reviewed such studies, he found moderate support for the spatial frequency hypothesis. However, the manipulations used in these studies have only crude and/or indirect effects on the spatial frequency content of the input, and thus they cannot be considered simple or straightforward manipulations of spatial frequency as opposed to other input variables (e.g., stimulus perceptibility; see Michimata & Hellige, 1987).In only four studies have quantitative forms of spatial filtering been employed to directly test the spatial frequency hypothesis. Sergent (1985) presented clear versus low-pass blurred faces and found, as predicted by the hypothesis, that low-pass blurring produced greater relative LH impairment. In a similar experiment, however, Sergent (1987) obtained an LH advantage with broad-pass faces and no hemispheric differences with low-pass faces. Christman (1990) used dioptric blur...

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Section: Resultsmentioning

confidence: 91%

Hemispheric differences are found in the identification, but not the detection, of low versus high spatial frequencies

Kitterle

Christman

Hellige

1990

Perception & Psychophysics

154

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“…The axes of this plot are the activities in two independent channels. 6 The section on double-knob paradigms describes how a model involving a multiplicity of mechanisms can be transformed to this For concreteness, consider a pattern consisting of a first plus third harmonic: P(k) = cos(fx) + k cos(3fx). High-spatial-frequency mechanisms whose peak sensitivities (fin) are above the third harmonic (fin > 3f) would be sensitive to the presence of the third harmonic and would not significantly respond to the fundamental.…”

Section: Single-knob Psychophysicsmentioning

confidence: 99%

Double-judgment psychophysics: problems and solutions

Klein

1985

J. Opt. Soc. Am. A

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Many paradigms for comparing identification thresholds with detection thresholds require the observer to make double judgments. We show that these paradigms can produce misleading results because of response biases and attentional shifts. For example, the subject's response bias plus correlated noise can mimic inhibition between channels. Some of these same problems can affect single-judgment paradigms. A detailed analysis of the doublejudgment forced-choice paradigm reveals that there are a multiplicity of optimal strategies, some of which enhance identification over detection. Several improved analysis techniques for minimizing the effects of cognitive factors are proposed for both the double-judgment forced-choice paradigm and the double-judgment rating-scale paradigm. A classification scheme for distinguishing different types of interactions and correlations is developed.When the new rating-scale algorithm is applied to the detection of well-separated spatial frequencies, substantial masking but negligible inhibition is found. The rating-scale paradigm is shown to be useful in revealing not only the sensitivity and the interactions of the underlying mechanisms but also the observer's information-processing strategies.Stimuli that are just barely visible provide a great challenge to the vision researcher. This regime between threshold and two or three times threshold, which we shall call the parathreshold regime (para from the Greek, meaning near, beyond), offers the opportunity for learning much about the bandwidths, interactions, nonlinearities, labeling, and other properties of the underlying mechanisms. 1 -7 One of the dominant features of the parathreshold regime is that some stimulus attributes can be identified. By comparing the identification threshold of a feature with its detection threshold, a quantitative scale of attributes can be developed. The challenge is that these properties are easily camouflaged by high-level processes such as attention shifts, criterion shifts, and nonoptimal detection strategies. The present paper describes some of the methodological problems associated with parathreshold psychophysics. Difficulties in interpreting the popular double-judgment, two-alternative forced-choice paradigm will be pointed out, and methods for overcoming some of the difficulties will be offered. A new method for analyzing double-judgment rating-scale data will also be proposed and applied to frequency-discrimination data.It is helpful to divide the different experimental paradigms into two categories: single knob and double knob. The term "knob" is used to evoke the image of a physical knob on the stimulus generator. The number of knobs is the number of degrees of freedom in the stimulus. We use the word "knob" rather than "dimension" because, as will become clear, some single-knob experiments require multiple dimensions for analysis. Single-knob stimuli can be represented on a straight line, and a central question in single-knob identificationdetection experiments is to ask to what extent the...

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“…In the case of orientation perception, this assumption is supported by experiments showing that the contrast thresholds of detection and identification coincide if the stimuli differ in orientation by more than 15° (Thomas & Gille, 1979;Vassilev, Simeonova, & Ziatkova, 1981). This orientation difference was assumed to be an estimate ofthe distance between the independent labeled channels (Thomas, Gille, & Barker, 1982;Vassilev, Simeonova, & Ziatkova, 1982). Thus, a system offinite number of such channels, not more than 12, would span the whole orientation range.…”

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confidence: 99%

Temporal characteristics of line orientation identification

Zlatkova

Vassilev

Mitov

2000

Perception & Psychophysics

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The hypothesis that identification of line orientation is based on different mechanisms-a detector mechanism at large orientation differences and a computational one at small orientation differenceswas tested in three experiments. The first two experiments compared reaction time and time of complete temporal summation (tc) in two tasks, line detection and line orientation identification. Identification at orientation differences 15°or more was similar to detection in several respects, suggesting that it was accomplished according to the principle of "labeled lines." In agreement with the initial hypothesis, identification at differences smaller than 15°had a slower time course and could not be explained by the "labeled lines" principle. Experiment 3 explored the orientation acuity as a function of exposure duration and stimulus energy. Energy could not completely substitute for time in providing high orientation acuity, a result suggesting the involvement of neurophysiological mechanisms of large time constants.

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Simultaneous visual detection and identification: theory and data

Cited by 60 publications

References 13 publications

Hemispheric differences are found in the identification, but not the detection, of low versus high spatial frequencies

Hemispheric differences are found in the identification, but not the detection, of low versus high spatial frequencies

Double-judgment psychophysics: problems and solutions

Temporal characteristics of line orientation identification

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