Improving Reading Speed in Peripheral Vision with Perceptual Learning: A Behavioral and fMRI Investigation

Abstract

Practicing a perceptual task often leads to improved performance, termed perceptual learning. The improvement is often specific to the task and trained retinal location. Here, we report on a project using psychophysics and fMRI to address two questions: Is perceptual learning in eccentric reading transferable to an untrained retinal locus or a task non-related to reading? Are there training-related changes in the functional responses in retinotopic or non-retinotopic areas of visual cortex? Four young normally sighted subjects were trained (1hour/day over 4days) to read sentences displayed in the lower visual field (10º eccentricity) using the Rapid Serial Visual Presentation (RSVP) paradigm. Pre- and post-training psychophysical tests included RSVP reading speed, visual span and orientation discrimination (Gabor patch) measurements in both the trained (lower) and untrained (upper) visual fields. Functional MRI measurements (BOLD) were recorded before and after training for: eccentric RSVP reading and grating orientation discrimination. The fMRI measurements used a rapid event-related design, with analysis focusing on multiple regions of visual cortex, including primary visual cortex (V1) and visual word form area (VWFA). Post-training measurements showed a significant gain in RSVP reading speed of 60% (±25%) in the trained visual field. This improvement partially transferred to the untrained location. Orientation discrimination thresholds were not significantly different after training. Preliminary data analysis showed that, following training, there was enhanced BOLD signal in the VWFA for the fastest presentation rate for both the trained and untrained locations, but not in the early visual cortex. Our behavioral data confirm the existence of perceptual training effects in eccentric reading with normal subjects. The training partially transferred to an untrained retinal location, but did not transfer to a task (orientation discrimination) unrelated to reading or letter recognition. Further exploration of our fMRI data may reveal additional cortical site(s) of this form of perceptual learning.

Meeting abstract presented at VSS 2012