Neural Theories of Simple Visual Discriminations*†

Blackwell, H. Richard

doi:10.1364/josa.53.000129

Cited by 296 publications

(90 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In fact, our regression-based approach allows to verify empirically one of the main predictions of SDT: that hit and false-alarm rates both increase parametrically with signal energy. In this respect, the finding that false alarms are not pure strategic guesses constitutes in itself a validation of SDT and allows the ruling out of other, finite-state models of detection, such as the high-threshold model (24).…”

Section: Discussionmentioning

confidence: 99%

Dissociable prior influences of signal probability and relevance on visual contrast sensitivity

Wyart

Nobre

Summerfield

2012

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

239

262

View full text Add to dashboard Cite

According to signal detection theoretical analyses, visual signals occurring at a cued location are detected more accurately, whereas frequently occurring ones are reported more often but are not better distinguished from noise. However, conventional analyses that estimate sensitivity and bias by comparing true- and false-positive rates offer limited insights into the mechanisms responsible for these effects. Here, we reassessed the prior influences of signal probability and relevance on visual contrast detection using a reverse-correlation technique that quantifies how signal-like fluctuations in noise predict trial-to-trial variability in choice discarded by conventional analyses. This approach allowed us to estimate separately the sensitivity of true and false positives to parametric changes in signal energy. We found that signal probability and relevance both increased energy sensitivity, but in dissociable ways. Cues predicting the relevant location increased primarily the sensitivity of true positives by suppressing internal noise during signal processing, whereas cues predicting greater signal probability increased both the frequency and the sensitivity of false positives by biasing the baseline activity of signal-selective units. We interpret these findings in light of “predictive-coding” models of perception, which propose separable top-down influences of expectation (probability driven) and attention (relevance driven) on bottom-up sensory processing.

show abstract

Section: Discussionmentioning

confidence: 99%

Dissociable prior influences of signal probability and relevance on visual contrast sensitivity

Wyart

Nobre

Summerfield

2012

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

239

262

View full text Add to dashboard Cite

show abstract

“…Blackwell (1963), in his critique of the theory of signal detectability, has focused most clearly on the importance of considering experimental procedures and stimulus displays in any theoretical analysis of visual masking. According to Blackwell, observers compare samples of sensory information only in the stimulus-comparison experiment wherein the task of the viewer is to judge whether an inner disk is brighter or darker than a concentric ring.…”

Section: Discussionmentioning

confidence: 99%

Visual detection of signals in the presence of continuous and pulsed backqrounds

Leshowitz

Tavb

Raab

1968

Perception & Psychophysics

125

View full text Add to dashboard Cite

“…The values for this ratio obtained in the present experiment range from 0.04 to 0.31, with a median of 0.08. In marked contrast, some typical visual functions yield a ratio of standard deviation to threshold of 0.30 (Heinz & Lippay, 1928), 0.311 to 0.539 (Blackwell, 1963), 0.42 (Hecht, Shlaer, & Pirenne, 1942), and 0.58 (Bouman & vanderVelden, 1947). A two-alternative forced-choice study by Green (1960) yields a ratio of 0.70 or more for auditory detection.…”

Section: Methodsmentioning

confidence: 99%

Electrocutaneous stimulation: Psychometric functions and temporal integration

Rollman

1969

Perception & Psychophysics

View full text Add to dashboard Cite

Electrical stimulation of the skin has been used by psychophysicists since the late 19th century. This form of cutaneous activation has become increasingly popular as equipment has improved, but our knowledge of the mechanism of stimulation is still incomplete. Grundfest (1959) has presented evidence to suggest that electrocutaneous stimuli probably bypass the specialized receptors and directly excite the afferent axons. This view leads to two important expectations about psychophysical observations with rectangular electrocutaneous pulses. First, the slope of the psychometric function obtained by the method of constant stimuli should be very steep. Pecher (1936Pecher ( , 1939 and Verveen (1960) found that the probability of firing single axons in frog sciatic nerve went from zero to unity as the amplitude of stimulating pulses varied by 1 or 2% of threshold. If percutaneous electrical pulses need to excite a small number of axons for detection, then the resulting psychometric function should climb rapidly. Only Schmid (1961) and Green (1962) have determined psychometric functions with electrocutaneous stimulation, and their experiments were not aimed at studying the detection process for stimuli of low intensity. The few data obtained by Green and from my preliminary experiments, however, confirm the prediction. Indeed, the results suggest that all of the variance of the psychometric function could reflect a relatively small variability in the output of the stimulating system. This argument is clearly similar to the physical quantum theory of vision. The preliminary data had been obtained with oscilloscopic calibration, which is accurate to only a few per cent. Accordingly, Experiment I obtained psychometric functions while a special electronic system monitored stimulating current to at least 0.3% accuracy.The second prediction from the thesis that electrocutaneous pulses directly excite the afferent nerves is that psychophysical strength-duration curves, which show how threshold varies with pulse width, should resemble the physiological strength-duration curves for mammalian A-fibers which innervate the skin. Electrocutaneous stimuli should fire the larger and, thus, more excitable A-fibers first. Hahn (1958) and Uttal (1958) have obtained such psychophysical curves. Hahn's data, however, do not go below O.l-msec duration, where the strength-duration curve should be steepest. Furthermore, he used pulses of different frequencies rather than single rectangular pulses. Uttal did not use constantcurrent stimulation but corrected his data to compensate for selective filtering of various frequency components by the skin. Through this indirect method, he found reciprocity below 0.1 msec. Since no direct, complete examination of the relation of intensity and duration for electrocutaneous pulses of very brief duration is available, Experiment 2 obtained the necessary data. EXPERIMENT 1 ApparatusStimulating equipment. The electrical stimuli were presented to the 0 through Grass silver electrodes, 8 mm in diam, filled ...

show abstract

Neural Theories of Simple Visual Discriminations*†

Cited by 296 publications

References 30 publications

Dissociable prior influences of signal probability and relevance on visual contrast sensitivity

Dissociable prior influences of signal probability and relevance on visual contrast sensitivity

Visual detection of signals in the presence of continuous and pulsed backqrounds

Electrocutaneous stimulation: Psychometric functions and temporal integration

Contact Info

Product

Resources

About