flanker task

We measure rats' ability to detect an oriented visual target grating located between two flanking stimuli ("flankers"). Flankers varied in contrast, orientation, angular position, and sign. Rats are impaired at detecting visual targets with collinear flankers, compared to configurations where flankers differ from the target in orientation or angular position. In particular, rats are more likely to miss the target when flankers are collinear. The same impairment is found even when the flanker luminance was signreversed relative to the target. These findings suggest that contour alignment alters visual processing in rats, despite their lack of orientation columns in the visual cortex. This is the first report that the arrangement of visual features relative to each other affects visual behavior in rats. To provide a conceptual framework for our findings, we relate our stimuli to a contrast normalization model of early visual processing. We suggest a pattern-sensitive generalization of the model that could account for a collinear deficit. These experiments were performed using a novel method for automated high-throughput training and testing of visual behavior in rodents.

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Meier*, PM, Flister*, ED, and Reinagel P (2011) Collinear features impair visual detection by rats. Journal of Vision 11(3)22, doi:10.1167/11.3.22

Meier, PM and Reinagel P (2011) Rat performance on visual detection task modeled with divisive normalization and adaptive decision thresholds. Journal of Vision 11(9)1 doi:10.1167/11.9.1.

Support J.S. McDonnel Foundation, National Eye Institute, NSF