Studies of Psychophysical Methods for Measuring Visual Thresholds*†

Blackwell, H. Richard

doi:10.1364/josa.42.000606

Cited by 102 publications

(46 citation statements)

References 4 publications

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“…where HR c,i is the catch-corrected hit rate for stimulus i, HR i is the obtained hit rate for stimulus i, and FA is the false-alarm rate [i.e., response rate to the catch stimulus (Blackwell, 1952)]. The reason for applying this formula is that a fraction of the rats' responses to nearthreshold stimuli presumably resulted from "guessing," i.e., emitting random licks without the presence of a sensation.…”

Section: Methodsmentioning

confidence: 99%

Integration of Vibrotactile Signals for Whisker-Related Perception in Rats Is Governed by Short Time Constants: Comparison of Neurometric and Psychometric Detection Performance

Stüttgen¹,

Schwarz²

2010

J. Neurosci.

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Rats explore environments by sweeping their whiskers across objects and surfaces. Both sensor movement and repetitive sweeping typical for this behavior require that vibrotactile signals are integrated over time. While temporal integration properties of neurons along the whisker somatosensory pathway have been studied extensively, the consequences for behavior are unknown. Here, we investigate the ability of headfixed rats to integrate information over time for the detection of near-threshold pulsatile deflection sequences applied to a single whisker. Psychometric detection performance was assessed with whisker stimuli composed of different numbers of pulses (1-31) delivered at varying frequencies (10, 20, 100 Hz). Detection performance indeed improved with increasing number and frequency of pulses, albeit this improvement was much lower than predicted by probabilistic combination, suggesting highly sublinear integration of pulses. This behavioral observation was reflected in the firing properties of concomitantly recorded barrel cortex neurons, which showed substantial response adaptation to repetitive whisker deflection. To estimate the integration time with which barrel cortex neuronal activity must be read out to match behavior, we constructed a model monitoring spiking activity of simulated neuronal pools, where spike trains were channeled through a leaky integrator with exponential decay. Detection was accomplished by simple threshold crossings. This simple model gave an excellent match of neurometric and psychometric data at surprisingly small time constants of 5-8 ms, thus limiting integration largely to Ͻ25 ms. This result carries important implications regarding sensory processing for whisker-mediated perception.

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Section: Methodsmentioning

confidence: 99%

Integration of Vibrotactile Signals for Whisker-Related Perception in Rats Is Governed by Short Time Constants: Comparison of Neurometric and Psychometric Detection Performance

Stüttgen¹,

Schwarz²

2010

J. Neurosci.

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“…Most psychophysics experiments are carefully designed such that subjects should make choices based only on the sensory evidence at hand. However, under such conditions, human observers exhibit nonsensory biases (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) For instance, in the classical two-alternative forced choice task, a subject is asked to make a perceptual decision based solely on the present sensory evidence (21) and to use success or failure feedback only to optimize their use of such sensory information (22). However, both mice (14) and humans (15,17,18) make choices that are biased by their recent history of successes and failures and are thus suboptimal.…”

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confidence: 99%

Adaptable history biases in human perceptual decisions

Abrahamyan

Silva

Dakin

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

200

259

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When making choices under conditions of perceptual uncertainty, past experience can play a vital role. However, it can also lead to biases that worsen decisions. Consistent with previous observations, we found that human choices are influenced by the success or failure of past choices even in a standard two-alternative detection task, where choice history is irrelevant. The typical bias was one that made the subject switch choices after a failure. These choice history biases led to poorer performance and were similar for observers in different countries. They were well captured by a simple logistic regression model that had been previously applied to describe psychophysical performance in mice. Such irrational biases seem at odds with the principles of reinforcement learning, which would predict exquisite adaptability to choice history. We therefore asked whether subjects could adapt their irrational biases following changes in trial order statistics. Adaptability was strong in the direction that confirmed a subject’s default biases, but weaker in the opposite direction, so that existing biases could not be eradicated. We conclude that humans can adapt choice history biases, but cannot easily overcome existing biases even if irrational in the current context: adaptation is more sensitive to confirmatory than contradictory statistics.

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“…Furthermore, Blackwell (1952) has shown that a pay-motive can have some influence on the observer's visual performance. The co-operation of the three observers was motivated by the highest principles, A.R.J.…”

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confidence: 99%

Cone‐monochromatism

Weale¹

1953

The Journal of Physiology

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In the absence of any other clue, a person with monochromatic vision is unable to appreciate differences between hues of equal luminance. His monochromatism is diagnosed by his ability to match any two colours merely by equating their luminances, when all other clues are absent. Two principal types of this defect have been described in the literature. One, rod-monochromatism, is so well known and its characteristics have been so extensively described that most visual physiologists are no longer interested in it. However, the other, cone-monochromatism, has been encountered so rarely that its very existence has been conceded only in pathological cases. The two types differ in their frequency of occurrence and mode of inheritance. Thus rod-monochromatism occurs once in thirty thousand, and many blood relations of one family can exhibit it. The incidence of cone-monochromatism, on the other hand, has been estimated at one in a hundred million (Pitt, 1944 a), and has never been noted more than once in a family. The two types differ also by their concomitant symptoms. Cone-monochromatism has none, while rod-monochromats suffer always from reduced visual acuity, and frequently from nystagmus and photophobia. The spectral variation of the rod-monochromatic sensitivity closely agrees with the absorption spectrum of visual purple: this fact, coupled with the central scotoma experienced by rod-monochromats, supports the view that the defect is due to the inactivity or absence of cone-mechanisms. A satisfactory explanation of cone-monochromatism has not been advanced.Since more detailed information on cone-monochromatism was urgently required because of the light it might shed on theories of colour vision in general, a nation-wide search for cone-monochromats was initiated in June 1950. There is little doubt that the apparent rarity of the defect is partly due to inadequate methods of detection: e.g. the Ishihara Tables are not very reliable in this respect (Weale, 1953). Accordingly, the methods of screening and detecting cone-monochromats were improved.

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Studies of Psychophysical Methods for Measuring Visual Thresholds*†

Cited by 102 publications

References 4 publications

Integration of Vibrotactile Signals for Whisker-Related Perception in Rats Is Governed by Short Time Constants: Comparison of Neurometric and Psychometric Detection Performance

Integration of Vibrotactile Signals for Whisker-Related Perception in Rats Is Governed by Short Time Constants: Comparison of Neurometric and Psychometric Detection Performance

Adaptable history biases in human perceptual decisions

Cone‐monochromatism

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