Yes / The goal of this study was to investigate the reference
frames used in perceptual encoding and storage of visual
motion information. In our experiments, observers viewed
multiple moving objects and reported the direction of motion
of a randomly selected item. Using a vector-decomposition
technique, we computed performance during smooth pursuit
with respect to a spatiotopic (nonretinotopic) and to a
retinotopic component and compared them with performance
during fixation, which served as the baseline. For the stimulus
encoding stage, which precedes memory, we found that the
reference frame depends on the stimulus set size. For a single
moving target, the spatiotopic reference frame had the most
significant contribution with some additional contribution
from the retinotopic reference frame. When the number of
items increased (Set Sizes 3 to 7), the spatiotopic reference
frame was able to account for the performance. Finally, when
the number of items became larger than 7, the distinction
between reference frames vanished. We interpret this finding
as a switch to a more abstract nonmetric encoding of motion
direction. We found that the retinotopic reference frame was
not used in memory. Taken together with other studies, our
results suggest that, whereas a retinotopic reference frame
may be employed for controlling eye movements, perception
and memory use primarily nonretinotopic reference frames.
Furthermore, the use of nonretinotopic reference frames appears
to be capacity limited. In the case of complex stimuli, the
visual system may use perceptual grouping in order to simplify
the complexity of stimuli or resort to a nonmetric abstract
coding of motion information.
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/11366 |
| Date | 13 January 2017 |
| Creators | Huynh, D.L., Tripathy, Srimant P., Bedell, H.E., Ogmen, Haluk |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Article, Accepted Manuscript |
| Rights | © The Psychonomic Society, Inc. 2017. The final publication is available at Springer via http://dx.doi.org/10.3758/s13414-016-1258-5 |
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