Mental imagery acuity in the peripheral visual field.

Subjects made judgements of resolution on two small dots that they either imagined or acutally observed at horizontal and vertical positions away from the point of eye fixation. As the distance between these two dots increased, the size of fields of resolution in imagery increased, in proportion to increases in the size of fields of resolution in perception. For vivid imagers, fields of resolution in imagery were the same size as those in perception, whereas for nonvivid imagers, fields of resolution in imagery were smaller than those in perception. In addition, fields of resolution in imagery and perception were virtually identical in shape, exhibiting similar horizontal eccentricity and vertical asymmetry. Fields within which attention can be distributed in imagery were also measured by having subjects make judgements of resolution on pairs of dot patterns imagined simultaneously on opposite sides of the point of eye fixation. These fields were smaller than fields of resolution for images of single dot patterns and were circular, as opposed to elliptical. These results suggest that peripheral acuity in visual imagery is limited by the same types of neural constraints that limit peripheral acuity in visual perception.