fMRI experiments: stimuli and results.

<p><i>Top row</i>: The blue standard (left), equiluminant yellow (middle), and equally bright (right) annuli used in the first fMRI experiment; the relative responses (percent signal change) of primary visual cortex (V1) to the these stimuli (in the same left-to-right order as shown in the left panels) are shown on the right for two subjects (S1, S2). Error bars indicate one standard error. <i>Bottom row</i>: Blue standard (left), equiluminant low-saturated blue (middle), and equally bright low-saturated blue (right) annuli used in the second fMRI experiment; again the relative response of primary visual cortex (V1) of two subjects to these stimuli are indicated on the right (S2, S3). Display conventions are as for the upper row. Evidently V1 activity is consistent with the probable image-source relationship rather than the characteristics of the stimuli as such.