Introduction. In cognition, audition and somatosensation, performance correlates strongly between di erent tasks suggesting the existence of common factors ...
No correlations between the strength of visual illusions Lukasz Grzeczkowski, Aaron M. Clarke, Fred W. Mast and Michael H. Herzog Laboratory of Psychophysics, Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland Department of Psychology, University of Bern, Switzerland
Introduction
Stimuli
In cognition, audition and somatosensation, performance correlates strongly between different tasks suggesting the existence of common factors (Frenzel et al., 2012). Surprisingly, this does not hold true for vision. For example, Vernier acuity and Gabor detection correlate very weakly (Cappe, Clarke, Mohr & Herzog, 2014). Here, we show similar results for visual illusions.
3 deg
6.3 deg
Observers included 144 people (69 females) visiting the SwissTech Convention Center for its inauguration. Age ranged from 8 to 81 years. Observers adjusted with a computer mouse the size, the luminance or the orientation of a target in six visual illusions.
2.4 deg
12 deg
4 deg
8 deg
6 deg
20 deg
5.5 deg
Results
4 2 r = 7.79x10-4 2 0 −2 −4 4 r2 = 0.164 2 0 −2 −4 −4 −2 0 2 4
r2 = 0.551
2(115) = 0.21, p = 1.72x10-7 r 1.5 1
0.5
r2= 0.006
r2 = 0.030
r2 = 0.017
r2 = 0.254
r = 0.065 p = 0.485 L.R. = 3.764
−0.5
(arc. deg.)
−4 −2 0 2 4
r = 0.001
2
r = 0.003
2
r = 0.555
r = 0.130 p = 0.164 L.R. = 1.807
r = 0.047 p = 0.612 L.R. = 4.229
−4 −2 0 2 4 2
r = 0.013
2
r = 0.576
r = 0.050 p = 0.591 L.R. = 4.165
r = 0.174 p = 0.060 L.R. = 0.802
r = 0.290 p = 0.001 L.R. = 0.029
−4 −2 0 2 4 r2 = 0.251
r = -0.112 p = 0.228 L.R. = 2.305
r = 0.035 p = 0.711 L.R. = 4.495
r = -0.078 p = 0.406 L.R. = 3.395
r = 0.013 p = 0.890 L.R. = 4.773
−4 −2 0 2 4 r = 0.028 p = 0.765 L.R. = 4.607
r = 0.244 p = 0.008 L.R. = 0.135
r = 0.012 p = 0.898 L.R. = 4.779
-5
r = -9.18x10 p = 0.999 L.R. = 4.819
2 6 r (115) = 0.02, p = 0.1763 4 2 0 −2
−4 −2 0 2 4 2
0
r = 0.169 p = 0.069 L.R. = 0.905
2(115) = 0.01, p = 0.1956 r 150
80
2 2 r (115) = 0.06, p = 0.0068 1.5 1 0.5 0 −0.5
80 60 40 20 0 −20
2(115) = 0.11, p = 0.0003 r 20 10 0 20
40
60
80
60 Data Random
40 20 2
χ (116) = 13.94, p = 1.00 0 0
r2(115) = 0.00, p = 0.7753
Age
In line with previous studies (Coren, 1973; Coren et al. 1976; Coren & Porac, 1987), our results suggest that, contrary to cognition, audition and somatosensation, there is no common factor for vision. Magnitudes of the Ebbinghaus and Ponzo-type were found to correlate with V1 surface area (Schwartzkopf, Song & Rees, 2011, 2013). However, our data support this claim only weakly because the spatial illusions correlated only weakly with each other.
Rank Analysis
100
100 50 0 −50 −100
−10
Discussion
Correlations of illusion strength were very low and for most comparisons not significant. Results for males and females did not differ significantly. Interestingly, illusion magnitude decreased with age for the Ebbinghaus, Ponzo-type, and tilt illusions. Our null results are supported by good test-retest reliability and a Bayesian analysis. Factorial analysis revealed no common factor.
Mean Rank
r2 = 0.004
(arc. deg.)
Ebbinghaus
Explained Variance (%)
4 2 r = 0.060 2 0 −2 −4
r2 = 0.002
Müller−Lyer
(cd/m2)
4 2 r = 1.44x10-4 2 0 −2 −4
r2 = 0.084
Sim. Contrast
(arc. deg.)
4 2= 8.42x10-9 r 2 0 −2 −4
r2 = 0.0002
Ponzo-Type
(cd/m2)
4 2 r = 0.028 2 0 −2 −4
White
(deg.)
Tilt
White
Ponzo-Type
Sim. Contrast
Müller−Lyer
Ebbinghaus
Tilt
20
40
60
Subject
80
100
5
6
PCA
60 50 40 30 20 10 0 1
2
3
4
7
REFERENCES: Cappe, C., Clarke, A., Mohr, C., & Herzog, M. H. (2014). Is there a common factor for vision? Journal of Vision, 14(8):4, pp.1–11. Coren, S., Porac, C. (1987). Individual differences in visual-geometric illusions: Predictions from measures of spatial cognitive abilities. Perception & Psychophysics, 41(3), pp. 211-219. Coren, S. (1973). Visual Spatial Illusions: Many Explanations. Science, 179, 4072, pp. 503-504. Coren, S., Girgus, J.S., Erlichman, H., & Hakistan. (1976). An empirical taxonomy of visual illusions. Perception & Psychophysics, 20(2), pp. 129-137. Frenzel, H., Bohlender, J., Pinsker, K., Wohlleben, B., Tank, J., Lechner, S. G., et al. (2012). A genetic basis for mechanosensory traits in humans. PLoS Biology, 10(5), e1001318. Schwartzkopf, D.S., Song, C., & Rees, G. (2011). The surface area of human V1 predicts the subjective experience of object size. Nature Neuroscience, 14(1), pp. 28-30 Song, C., Schwartzkopf, D.S., & Rees, G. (2013). Variability in visual cortex size reflects tradeoff between local orientation sensitivity and global orientation modulation. Nature Communications, 4:2201.
