Figure 2.
Perceptual elongations after 10 min and 2 h of deprivation. The figure depicts the mean elongation judgment along the axis of predicted distortion (i.e., the horizontal axis for stimuli presented to the left and right of the BS; the vertical axis for stimuli presented above and below the BS), as a function of stimulus aspect ratio (see black and gray rectangles). The black lines show the undeprived conditions (solid black line, right eye was patched; dashed black line, neither eye patched, i.e., binocular viewing). The blue and green lines show the deprived conditions at 2 h and 10 min, respectively. In the undeprived control conditions, a square (x-axis: 0% difference in width and height) is perceived veridically (y-axis: 0 elongation judgment or square). In the deprived condition, this same stimulus is seen as elongated along the predicted axis of distortion (i.e., wider when presented to the left and right of the BS, and taller when presented to above and below the BS). More generally, the upward shift of the curves in the deprived conditions (blue and green lines) indicates an elongation of all rectangles along the axis of predicted distortion after 2 h of deprivation and after 10 min. The PSE indicates the rectangles that were perceived as squares after deprivation (shown in red): the PSE was −9%, which indicates that a rectangle either 9% thinner than a square (if presented to the left and right of the BS) or 9% shorter than a square (if presented above and below the BS) was perceived as a square. The 9% magnitude of elongation was significantly different from 0 (in which 0 indicates no distortion and was outside the 95% confidence interval around the PSE) after both 10 min and 2 h of deprivation, and the magnitude of the effect did not differ in the two cases (t(9) = 0.35; p = 0.73). Moreover, the effect was significantly greater after each deprived condition than in each undeprived control condition (t(9) = 4.54, 3.36 for 10 min vs binocular and monocular controls, respectively, and 6.24, 4.81 for 2 h vs binocular and monocular controls, respectively; all 4 p values <0.01). No significant elongation was found in either of the undeprived control conditions (the 95% confidence interval around the PSE for each condition included 0), nor did the two conditions differ from each other (t(9) = 0.51; p = 0.62).