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Paper   IPM / Cognitive / 7490
School of Cognitive Sciences
  Title:   Orientation Information of Unresolvable Gabor Patches Primes Ambiguous Motion but not Serial Search
  Author(s):  R. Rajimehr
  Status:   In Proceedings
  Proceeding: ECVP
  Year:  2003
  Supported by:  IPM
  Abstract:
It has been demonstrated that in a choice between movement along lines drawn parallel or orthogonal to possible motion paths, observers more often see movement along the lines parallel to the motion path. Lines indicating the path of movement can generate the perception of a biased bistable apparent motion direction and disambiguate bistable motion display (Francis and Kim, 1999 Perception 28 1243 - 1255). In the first experiment, it was shown that orientation information of Gabor patches whose spatial frequencies were beyond the perceptual resolution limit (unresolvable) could perceptually prime a specific direction in a bistable motion paradigm even better than that of resolvable Gabor patches. In the second experiment, an orientation array with either resolvable or unresolvable oriented items was presented before a serial search task. The target of serial search task at the location of unresolvable singleton (unique item) in the orientation array was not primed as well as the target at the location of resolvable singleton, implying that no orientation-dependent interactions were observed when several unresolvable Gabor patches were placed in close proximity. The results suggest that, although orientation signals are registered at least at the earliest stages of cortical processing without necessarily being consciously perceived, yet the processing of orientation difference and contextual modulation of orientation signals could not happen in such a perceptually unresolvable condition. [The author wishes to thank Patrick Cavanagh for insightful comments.]


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