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X. Huang, S. Blau, M. A. Paradiso; Aspects of human detection and discrimination correlate with macaque V1 physiology. Journal of Vision 2001;1(3):201. doi: https://doi.org/10.1167/1.3.201.
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© ARVO (1962-2015); The Authors (2016-present)
We previously found that when a stimulus is introduced into the RF of a macaque V1 neuron while simultaneously changing the background luminance, the response consisted of a rapid transient followed by more sustained secondary activity. Stimulus contrast was reflected in the latency of the delayed response and orientation in its magnitude. The transient part of the response appeared to signal simply that the visual scene changed. In contrast, when a stimulus was introduced without a background change, stimulus attributes were correlated with the initial response. The present human psychophysical study used a masking paradigm to test perceptual predictions of these results. A bar was flashed on for 12 ms followed, after some SOA, by a mask. The bar was either introduced onto a static background or flashed simultaneously with a background luminance change. Using a 2AFC procedure, subjects either discriminated bar orientation or detected the presentation of a stimulus preceding the mask. We found that in the orientation discrimination paradigm a longer SOA was needed in the changing background conditions to match performance in the static background conditions. Conversely, at a fixed SOA, performance in the static and changing background conditions could be matched by using a higher bar contrast when the background changed. We also found that when the background changed, a longer SOA was needed to discriminate bar orientation than to detect a stimulus preceding the mask. At all SOAs, less bar contrast was needed for detection than discrimination. These results suggest that orientation information is available more slowly when the background changes and this “disadvantage” can be overcome by raising the bar contrast. In conclusion, perceptual access and sensitivity to orientation correlate with the response of V1 neurons. Perceptually, as physiologically, the temporal representation of information depends on the manner in which the visual scene changes.
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