Abstract
The role of expertise in visual search has largely been explored using medical images. Typically radiographers search for anomalies in human anatomical structures. In medical imaging, targets are often ambiguous, generating high levels of misses/false alarms. Expertise is also restricted to a specific sub group making experimentation challenging. Together, these conditions make the study of perceptual expertise difficult. Here, we explore whether visual expertise effects occur in the identification of letter transpositions on QWERTY computer keyboards in an eye-movement study. Standard QWERTY keyboards follow a structure defined by convention that allows for simple manipulations in layout. By transposing letters we created a set of keyboards, where deviations from the normal arrangement could be graded as low, medium or high. Expertise was determined by performance on a typing speed test. Experts were defined as typing at or more than 60 words per minute and novices were defined as typing at 50 words per minute or less. Participants performed a go/no-go normal/manipulated keyboard decision task responding only when manipulated keyboards were presented. We recorded behavioural response time and accuracy measures in addition to eye movements. The results showed experts and novices to be different in accuracy but not response time. Crucially, experts were faster to detect manipulated regions than novices, a difference that increased with extent of manipulation. Additionally, experts spent less verification time fixating the transpositions themselves. We suggest that experts can use gist to detect deviations from the standard QWERTY keyboard arrangement. While a novel finding in its own right, this finding mimics other effects of perceptual expertise reported in the literature. Demonstrating effects of perceptual expertise in this stimulus domain allows future studies to more readily parameterize effects of perceptual expertise.
Meeting abstract presented at VSS 2014