October 2003
Volume 3, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   October 2003
Dynamic classification images reveal the effects of perceptual learning in a hyperacuity task
Author Affiliations
  • Jason M Gold
    Department of Psychology, Indiana University, Bloomington, IN, USA
Journal of Vision October 2003, Vol.3, 162. doi:10.1167/3.9.162
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      Jason M Gold; Dynamic classification images reveal the effects of perceptual learning in a hyperacuity task. Journal of Vision 2003;3(9):162. doi: 10.1167/3.9.162.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: Performance in hyperacuity tasks often improves with practice. One possible mechanism for this effect is an improvement in the spatial tuning of observers' templates. Here, I use response classification to measure trial-by-trial changes in observers' templates with practice in a vernier acuity task. Methods: 3 observers discriminated between 2 vertical line segments in which the entire top half was shifted by 1 pixel (∼20′) to the left or right. On each trial, a vernier stimulus was chosen randomly and presented in high contrast Gaussian white noise. Each observer participated in 1000 trials/day over the course of 10 days. Contrast thresholds were measured during each session with a staircase that maintained ∼71% correct performance throughout the session. Results & Conclusions: Practice reduced thresholds by a factor of ∼1.5 over the course of the experiment. A series of N classification images was computed using the noise shown on trials N through N+2,000 (where N ranged from 1 to 8,000). The result was a classification movie that dynamically revealed the changes that took place in an observer's linear template over time. When viewed in rapid succession, the series of images showed a stable template slowly emerging from a background of noise. This effect was quantified by cross-correlating each human classification image with the classification image for a model observer that a) assumed both the bottom and top halves of the vernier stimuli were shifting by 1 pixel in opposite directions; and b) was subject to a modest amount of spatial uncertainty. The correlation between the human and model classification images increased systematically by a factor of ∼1.5 over the course of the experiment. I am currently using double-pass response consistency and spatial jitter to measure any reductions in multiplicative internal noise and/or spatial uncertainty that may have contributed to the changes that took place in the classification images over time.

Gold, J. M.(2003). Dynamic classification images reveal the effects of perceptual learning in a hyperacuity task [Abstract]. Journal of Vision, 3( 9): 162, 162a, http://journalofvision.org/3/9/162/, doi:10.1167/3.9.162. [CrossRef]
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