Direction discrimination for band-pass filtered random dot kinematograms.
When an array of random dots is displaced, the ability to report the direction of apparent motion is subject to an upper spatial limit (dmax). As the size of the displacement is increased, direction discrimination errors show a monotonic increase that becomes asymptotic at a chance level. We have me...
| Main Authors: | , |
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| Format: | Journal article |
| Language: | English |
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1990
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| _version_ | 1797071815039778816 |
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| author | Cleary, R Braddick, O |
| author_facet | Cleary, R Braddick, O |
| author_sort | Cleary, R |
| collection | OXFORD |
| description | When an array of random dots is displaced, the ability to report the direction of apparent motion is subject to an upper spatial limit (dmax). As the size of the displacement is increased, direction discrimination errors show a monotonic increase that becomes asymptotic at a chance level. We have measured direction discrimination using spatially band-pass filtered random dots. These stimuli do not yield a monotonic increase in errors. Rather, for displacements greater than around 1 cycle of the stimulus centre frequency (Fc), performance oscillates about chance, with displacements of 1 1/4 cycles of Fc yielding systematic errors in perceived direction. We analyse this pattern of performance in terms of the stimulus autocorrelation function and conclude that dmax can be taken as lying on the initial rising portion of the displacement versus error function. Using this definition we find, in line with the results of Chang and Julesz (1985), that dmax scales inversely with Fc. Contrary to the results of Chang and Julesz, we find that this scaling holds beyond 4 c/deg. |
| first_indexed | 2024-03-06T22:58:41Z |
| format | Journal article |
| id | oxford-uuid:614f6865-c142-4bfa-999f-b7717aa14b16 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T22:58:41Z |
| publishDate | 1990 |
| record_format | dspace |
| spelling | oxford-uuid:614f6865-c142-4bfa-999f-b7717aa14b162022-03-26T17:59:12ZDirection discrimination for band-pass filtered random dot kinematograms.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:614f6865-c142-4bfa-999f-b7717aa14b16EnglishSymplectic Elements at Oxford1990Cleary, RBraddick, OWhen an array of random dots is displaced, the ability to report the direction of apparent motion is subject to an upper spatial limit (dmax). As the size of the displacement is increased, direction discrimination errors show a monotonic increase that becomes asymptotic at a chance level. We have measured direction discrimination using spatially band-pass filtered random dots. These stimuli do not yield a monotonic increase in errors. Rather, for displacements greater than around 1 cycle of the stimulus centre frequency (Fc), performance oscillates about chance, with displacements of 1 1/4 cycles of Fc yielding systematic errors in perceived direction. We analyse this pattern of performance in terms of the stimulus autocorrelation function and conclude that dmax can be taken as lying on the initial rising portion of the displacement versus error function. Using this definition we find, in line with the results of Chang and Julesz (1985), that dmax scales inversely with Fc. Contrary to the results of Chang and Julesz, we find that this scaling holds beyond 4 c/deg. |
| spellingShingle | Cleary, R Braddick, O Direction discrimination for band-pass filtered random dot kinematograms. |
| title | Direction discrimination for band-pass filtered random dot kinematograms. |
| title_full | Direction discrimination for band-pass filtered random dot kinematograms. |
| title_fullStr | Direction discrimination for band-pass filtered random dot kinematograms. |
| title_full_unstemmed | Direction discrimination for band-pass filtered random dot kinematograms. |
| title_short | Direction discrimination for band-pass filtered random dot kinematograms. |
| title_sort | direction discrimination for band pass filtered random dot kinematograms |
| work_keys_str_mv | AT clearyr directiondiscriminationforbandpassfilteredrandomdotkinematograms AT braddicko directiondiscriminationforbandpassfilteredrandomdotkinematograms |