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. Author manuscript; available in PMC: 2011 Apr 1.
Published in final edited form as: J Cogn Neurosci. 2011 Jan;23(1):119–136. doi: 10.1162/jocn.2010.21417

Figure 1.

Figure 1

Main experimental stimuli and behavioral results. (A) On each trial, Gabor stimuli appeared at one of five possible eccentricity conditions, ranging from 8.43° to 9.65° from a central fixation point. The range of eccentricities pictured is exaggerated for visualization purposes. The Gabors flickered in counterphase at 7.5 Hz and were present for the duration of each 10 second trial. A white annulus around the fixation point during the last 2 sec of each trial cued subjects to respond, indicating which of the five conditions was present. In a sixth baseline condition, only the fixation point was present for 10 sec. The behavioral and the correlation analyses refer to the separations between the five stimulus conditions—these are indicated below the stimuli (in degrees visual angle). (B) Subjects’ sensitivity (in d’ units, see MacMillan & Creelman, 2004) is plotted against stimulus separation. The positive trend in this plot indicates that the five stimulus positions sampled the dynamic range of subjects’ discrimination sensitivity. The overall hit rate was 58%. (C) Histogram of the response errors for all trials in the main experiment, binned by the distance between the correct and the actual responses. For example, if, on a given trial, the Gabors were presented in position 4 (9.34° from fixation) but the subject responded with position 3, that trial is binned in response error (−1). The trials in solid gray at response error 0 are the trials in which subjects responded correctly; we exclusively used the missed trials (dotted bars; 42% of total trials), in which perceived and physical positions were dissociated in the analysis of the main experiment. (D) An example trial. The Gabor stimuli were present for the duration of each 10-sec trial. At a random time during the first 8 sec of each trial, a small texture (either a radial or a concentric grating) appeared for 500 msec at 9.04° from fixation in a random quadrant. During the last 2 sec of the trial, a second texture appeared at the same eccentricity in a random quadrant; the type of texture matched the first on 50% of the trials. At the end of the trial, subjects gave two responses, indicating the positions of the Gabors (5AFC) and whether the two presented textures were the same (2AFC).