Carrasco, M. & Frieder, K.S. (1997). Cortical magnification neutralizes
the eccentricity effect in visual search. Vision Research,
We report two visual search experiments that explain an eccentricity
effect previously found: detection of both feature and conjunction targets
becomes increasingly less efficient as the orientation target appears
at more distant field eccentricities (Carrasco et al., 1995). By cortically
magnifying the stimuli we flattened out this effect for both feature and
conjunction tasks. We conclude that spatial resolution factors affect
visual search findings that have hitherto been attributed to covert attention.
We stress the importance of analyzing data by target position to minimize
the confound of the set size effect an retinal/field eccentricity. An
alternative theory of orientation asymmetries is offered.