Cite as:
Tjan B S, Chung S T L, Levi D M, 2002, "How many functional factors does it take to explain perceptual learning?" Perception 31 ECVP Abstract Supplement

How many functional factors does it take to explain perceptual learning?

B S Tjan, S T L Chung, D M Levi

Performance for many visual tasks improves with practice. We reported that improvements in identifying letters in peripheral vision is due to an increase in sampling efficiency, and not a reduction in intrinsic noise (Chung et al, 2001 Investigative Ophthalmology & Visual Science 42 Supplement, 3931). These two factors of the linear-amplifier model (LAM) depend on criterion d'. Here, we examine the functional nature of perceptual learning in a criterion-independent manner by using the perceptual template model (PTM, Lu and Dosher, 1999 Journal of the Optical Society of America A 16 764 - 778). PTM extends LAM by adding transducer nonlinearity and multiplicative noise. Psychometric functions for identifying single letters embedded in 6 external-noise levels were collected over 6 days of practice. Contrast thresholds at d' = 0.8, 1.7, 2.7 were determined per noise level. PTM was used to fit each set of threshold-vs-noise-contrast data. Four of the five observers improved with practice and showed a reduction in internal additive noise. Three of the four also showed external-noise exclusion. No significant reduction in multiplicative noise was observed. Removing transducer nonlinearity from PTM caused these factors to be criterion-dependent; however, removing multiplicative noise had little effect. Internal-noise reduction and external-noise exclusion appear to be the common mechanisms of perceptual learning in peripheral vision. Transducer nonlinearity is necessary for these two factors to be criterion-independent.[Supported by grants NIH EY12810 and EY01728.]

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