The Neurophysiology of Backward Visual Masking: Information Analysis
n Backward masking can potentially provide evidence of the time needed for visual processing, a fundamental constraint that must be incorporated into computational models of vision. Although backward masking has been extensively used psychophysically, there is little direct evidence for the effects...
| Format: | Journal article |
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Massachusetts Institute of Technology
1999
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| _version_ | 1797081880647958528 |
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| collection | OXFORD |
| description | n Backward masking can potentially provide evidence of the time needed for visual processing, a fundamental constraint that must be incorporated into computational models of vision. Although backward masking has been extensively used psychophysically, there is little direct evidence for the effects of visual masking on neuronal responses. To investigate the effects of a backward masking paradigm on the responses of neurons in the temporal visual cortex, we have shown that the response of the neurons is interrupted by the mask. Under conditions when humans can just identify the stimulus, with stimulus onset asynchronies (SOA) of 20 msec, neurons in macaques respond to their best stimulus for approximately 30 msec. We now quantify the information that is available from the responses of single neurons under backward masking conditions when two to six faces were shown. We show that the information available is greatly decreased as the mask is brought closer to the stimulus. The decrease is more marked than the decrease in Žring rate because it is the selective part of the Žring that is especially attenuated by the mask, not the spontaneous Žring, and also because the neuronal response is more variable at short SOAs. However, even at the shortest SOA of 20 msec, the information available is on average 0.1 bits. This compares to 0.3 bits with only the 16-msec target stimulus shown and a typical value for such neurons of 0.4 to 0.5 bits with a 500- msec stimulus. The results thus show that considerable information is available from neuronal responses even under backward masking conditions that allow the neurons to have their main response in 30 msec. This provides evidence for how rapid the processing of visual information is in a cortical area and provides a fundamental constraint for understanding how cortical information processing operates. n |
| first_indexed | 2024-03-07T01:20:19Z |
| format | Journal article |
| id | oxford-uuid:9015e185-c5a5-49cc-9e53-ea2e6500c341 |
| institution | University of Oxford |
| last_indexed | 2024-03-07T01:20:19Z |
| publishDate | 1999 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | oxford-uuid:9015e185-c5a5-49cc-9e53-ea2e6500c3412022-03-26T23:09:08ZThe Neurophysiology of Backward Visual Masking: Information AnalysisJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:9015e185-c5a5-49cc-9e53-ea2e6500c341Experimental PsychologyOxford University Research Archive - Valet Massachusetts Institute of Technology1999n Backward masking can potentially provide evidence of the time needed for visual processing, a fundamental constraint that must be incorporated into computational models of vision. Although backward masking has been extensively used psychophysically, there is little direct evidence for the effects of visual masking on neuronal responses. To investigate the effects of a backward masking paradigm on the responses of neurons in the temporal visual cortex, we have shown that the response of the neurons is interrupted by the mask. Under conditions when humans can just identify the stimulus, with stimulus onset asynchronies (SOA) of 20 msec, neurons in macaques respond to their best stimulus for approximately 30 msec. We now quantify the information that is available from the responses of single neurons under backward masking conditions when two to six faces were shown. We show that the information available is greatly decreased as the mask is brought closer to the stimulus. The decrease is more marked than the decrease in Žring rate because it is the selective part of the Žring that is especially attenuated by the mask, not the spontaneous Žring, and also because the neuronal response is more variable at short SOAs. However, even at the shortest SOA of 20 msec, the information available is on average 0.1 bits. This compares to 0.3 bits with only the 16-msec target stimulus shown and a typical value for such neurons of 0.4 to 0.5 bits with a 500- msec stimulus. The results thus show that considerable information is available from neuronal responses even under backward masking conditions that allow the neurons to have their main response in 30 msec. This provides evidence for how rapid the processing of visual information is in a cortical area and provides a fundamental constraint for understanding how cortical information processing operates. n |
| spellingShingle | Experimental Psychology The Neurophysiology of Backward Visual Masking: Information Analysis |
| title | The Neurophysiology of Backward Visual
Masking: Information Analysis |
| title_full | The Neurophysiology of Backward Visual
Masking: Information Analysis |
| title_fullStr | The Neurophysiology of Backward Visual
Masking: Information Analysis |
| title_full_unstemmed | The Neurophysiology of Backward Visual
Masking: Information Analysis |
| title_short | The Neurophysiology of Backward Visual
Masking: Information Analysis |
| title_sort | neurophysiology of backward visual masking information analysis |
| topic | Experimental Psychology |