- Eccentricity:
If the element eccentricity increases as the set-size increases in the
display, then the target/distractor discriminability might decrease as the set-size
increases. In this case, one might obtain additional degradation in performance in large
set-size conditions due to the increase in eccentricity. A limited capacity model might
fit the model but this limited capacity would reflect the fact that the retinal periphery
does not have the quality of processing (for certain tasks) as the fovea.
(see Carracso et al, 1995).
- Eye movements:
If eye-movements are not controlled in brief displays, observers might
have time to fixate all elements in the display for set-size 2 (n=2) but not for set-size
16. In this case, one might obtain an increased performance in n=2 condition with respect
to the n=16 condition and the data might be better fit by a limited capacity model than a
noisy-parallel. However, the limited capacity is not reflecting the central visual
processing but rather the inability of the observer to move his/her eyes rapidly enough to
fixate all elements in the n=16 condition.
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