Article Figures & Data
Figures
- Figure 1.
Schematic of experimental design and stimulus set. a, A schematic of stimulus presentation paradigm. The stimuli were presented for 100 ms in one of the eight locations around the fixation point. The fixation point remained visible until the subject pressed a valid key. The next trial started after a 500 ms intertrial interval. A dashed line and black points show the location of the stimulus presentation for depiction purposes (note that the locations depicted in the middle plot were not shown to the subjects). They were not present in the experiment. b, Chair and animal body stimuli without any noise. c, Noisy stimuli of an example chair and animal body image. Numbers at the bottom indicate the levels of the visual signal.
- Figure 2.
Differences in subjects’ hit rate for body and chair categories. Subjects’ performance in detecting body and chair categories varies between foveal and extrafoveal locations. a, The response curve of subjects (mean ± SEM) across the visual field for different levels of visual signal. b, Average hit rate across subjects for detecting body and chair at the fovea, upper (45, 90, and 135°), and lower (225, 270, and 315°) visual fields for less noisy stimuli. c, Hit rate range across levels of visual signals is plotted for each location. The shaded areas show the hit rate range (max–min). p-values of two-sided Wilcoxon's signed-rank test are reported for each location. *p < 0.05, **p < 0.01, ***p < 10−3.
- Figure 3.
Subjects’ hit rate to detect less noisy stimuli (80–100%) of body and chair. There was variability in responses within the body and chair categories across the extrafoveal locations of the visual field. a, Individual subjects’ hit rate in the lower and upper visual fields. The histogram in the bottom right corner shows the population distribution of lower minus upper visual field hit rate for chair and body. The plot in the top left part shows the cumulative distribution of the difference between lower and upper visual field hit rates. b, Individual subjects’ hit rate in the right and left visual fields. The arrows show the mean of the distributions. c, The violin plot shows the hit rate in each visual field quadrant. We calculated the average hit rate across three neighboring locations for each quadrant (e.g., averaging 0, 45, and 90° for the upper-right quadrant). Chair is plotted in blue and body in red; n = 16. *p < 0.05, **p < 0.01, ***p < 10−3.
- Figure 4.
Mean hit rate as a function of stimulus location in the visual field. There was a bias in category detection across different regions of the visual field, as indicated by the computed ABI (animacy bias index). a, Subplots represent the average hit rate of all subjects. Chair is plotted in blue and body in red. The hit rate values are depicted in the right plot. b, The average ABI is plotted for different levels of the visual signals. Each radar plot corresponds to one visual signal.
- Figure 5.
Relationship between visual signal and location of stimulus presentation. There were high positive ABI values in the lower-left visual quadrant at low levels of visual signals. a, Color plot of average animacy bias for all subjects illustrates the influence of location and visual signals on category detection bias. The mean and SEM of animacy bias are plotted as a function of location (b) and visual signal (c).
- Figure 6.
Individual subjects’ hit rate for full noise stimuli. There was no significant difference in full noise bias across locations. The performance of chair and body (expressed as the ratio of reported body/chair trials to all trials) in response to full noise stimuli is plotted for each location (a). The scatter plots of chair ratio for (b) lower versus upper and (c) left versus right visual field stimuli are plotted for all subjects for the full noise stimuli (n = 13; the full noise stimuli were not presented to the three subjects). The histograms on the scatter plots illustrate the distribution of the chair ratio differences.
- Figure 7.
Body and chair category recognition across signal levels and locations after correction for location-contingent decision bias. Heterogeneity persisted in body category recognition, while normalized detection showed no bias toward chairs. The left panel (a) depicts the results of category recognition after correcting for the full noise detection bias for 80–100% visual signal. The right panel (b) shows the bias-corrected category recognition for both body and chair categories at different signal level covering.
- Figure 8.
Individual subjects’ reaction times for detecting body and chair categories in the high level of visual signal (80–100%). Category recognition for both body and chair categories resulted in similar reaction times across various locations in the visual field. The scatter plot of reaction times for category detection in the (a) lower versus upper and (b) right versus left visual field stimuli. The bottom right histograms show the cumulative distribution of the difference between the lower/upper and right/left visual field reaction times.
Tables
- Table 1.
Hit rate range (difference of minimum and maximum hit rate) in each location for body and chair category
Location Body Chair p-value 0° 0.30 ± 0.04 0.41 ± 0.04 0.17 45° 0.28 ± 0.03 0.44 ± 0.04 0.02 90° 0.25 ± 0.02 0.37 ± 0.04 0.04 135° 0.26 ± 0.04 0.45 ± 0.03 0.01 180° 0.26 ± 0.04 0.48 ± 0.04 0.01 225° 0.25 ± 0.03 0.49 ± 0.04 0.005 270° 0.23 ± 0.02 0.46 ± 0.04 0.005 315° 0.25 ± 0.03 0.45 ± 0.04 0.003 The reported p-values are adjusted with FDR correction.
Visual signal Category Mean hit rate ± SEM p-value Upper visual field Lower visual field 1–39% Animal body 0.54 ± 0.0 4 0.61 ± 0.04 0.1 Chair 0.48 ± 0.0 3 0.41 ± 0.04 0.002 40–59% Animal body 0.55 ± 0.03 0.63 ± 0.03 0.01 Chair 0.50 ± 0.03 0.43 ± 0.03 0.004 60–79% Animal body 0.61 ± 0.04 0.68 ± 0.02 0.05 Chair 0.71 ± 0.06 0.65 ± 0.04 0.15 The p-values reported compare the upper and lower hit rates for each category.
- Table 3.
Average hit rate, animacy bias index (ABI), and d′ value in each visual signal and location of visual field
Visual signal Location Mean hit rate ± SEM (body) Mean hit rate ± SEM (chair) ABI ± SEM d′ value 1–39% 0° 0.53 ± 0.04 0.49 ± 0.05 0.05 ± 0.09 −0.03 45° 0.55 ± 0.04 0.44 ± 0.04 0.10 ± 0.08 0.58 90° 0.54 ± 0.04 0.50 ± 0.04 0.04 ± 0.07 −0.33 135° 0.56 ± 0.04 0.49 ± 0.04 0.05 ± 0.07 0.20 180° 0.59 ± 0.04 0.40 ± 0.04 0.19 ± 0.08 0.55 225° 0.64 ± 0.03 0.36 ± 0.03 0.28 ± 0.06 1.84 270° 0.61 ± 0.04 0.41 ± 0.03 0.18 ± 0.07 1.44 315° 0.58 ± 0.04 0.46 ± 0.05 0.11 ± 0.09 0.76 40–59% 0° 0.55 ± 0.04 0.52 ± 0.04 0.03 ± 0.08 0.06 45° 0.58 ± 0.04 0.50 ± 0.05 0.08 ± 0.08 0.32 90° 0.54 ± 0.04 0.53 ± 0.04 0.02 ± 0.08 −0.23 135° 0.53 ± 0.04 0.48 ± 0.04 0.05 ± 0.08 0.04 180° 0.59 ± 0.04 0.43 ± 0.04 0.16 ± 0.07 0.88 225° 0.66 ± 0.04 0.40 ± 0.03 0.24 ± 0.06 1.47 270° 0.64 ± 0.05 0.40 ± 0.07 0.24 ± 0.08 1.45 315° 0.60 ± 0.05 0.50 ± 0.05 0.09 ± 0.08 0.70 60–79% 0° 0.65 ± 0.03 0.71 ± 0.04 −0.03 ± 0.05 −0.21 45° 0.61 ± 0.04 0.71 ± 0.04 −0.07 ± 0.05 −0.52 90° 0.58 ± 0.04 0.71 ± 0.05 −0.10 ± 0.08 −0.82 135° 0.65 ± 0.04 0.71 ± 0.06 −0.03 ± 0.08 −0.28 180° 0.74 ± 0.03 0.70 ± 0.04 0.04 ± 0.06 0.29 225° 0.70 ± 0.03 0.61 ± 0.04 0.07 ± 0.05 0.44 270° 0.68 ± 0.03 0.65 ± 0.05 0.03 ± 0.06 0.12 315° 0.65 ± 0.04 0.71 ± 0.04 0.04 ± 0.06 −0.36 80–100% 0° 0.72 ± 0.02 0.86 ± 0.03 −0.09 ± 0.02 −1.23 45° 0.67 ± 0.02 0.87 ± 0.02 −0.12 ± 0.02 −2.55 90° 0.65 ± 0.03 0.87 ± 0.02 −0.15 ± 0.03 −2.15 135° 0.68 ± 0.04 0.88 ± 0.02 −0.13 ± 0.03 −1.56 180° 0.80 ± 0.02 0.86 ± 0.02 −0.03 ± 0.02 −0.69 225° 0.77 ± 0.02 0.81 ± 0.02 −0.02 ± 0.02 −0.16 270° 0.73 ± 0.02 0.84 ± 0.02 −0.07 ± 0.02 −0.77 315° 0.72 ± 0.03 0.84 ± 0.02 −0.08 ± 0.03 −0.61
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