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Michael Melnick, Duje Tadin; A strong interactive link between sensory discrimination and intelligence. Journal of Vision 2011;11(11):810. doi: 10.1167/11.11.810.
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© ARVO (1962-2015); The Authors (2016-present)
The general goals of perception are (1) expedient processing of relevant information and (2) suppression of irrelevant information. These same goals are also central to cognitive processes, including general intelligence (Galton, 1883). The existence of this general constraint for efficient information processing might indicate the existence of common ‘processes’ that underlie both general intelligence and sensory discriminations (Cattell, 1886), predicting links between perceptual performance and abilities associated with intelligence.
We addressed this question by measuring duration thresholds for motion direction discriminations of stimuli varying in size. The typical (group-level) result is a considerable increase in thresholds with increasing stimulus size – a finding taken to indicate spatial suppression of large, background-like motions (Tadin et al., 2003). We utilized duration thresholds because they are effectively a measure of how quickly the visual system accumulates task-relevant stimulus information (Gold & Shadlen, 2000). This, in turn, suggests that lower duration thresholds may correlate with higher IQ. However, as higher thresholds for large stimuli indicate effective spatial suppression, higher IQ may correlate with stronger spatial suppression. Our results confirmed this interactive link between IQ and sensory discriminations. Specifically, high IQ subjects were better-than-normal at perceiving motion of small stimuli, but worse-than-normal at discriminating motion of large stimuli – i.e., exhibiting stronger-than-normal spatial suppression. The correlation between IQ and suppression strength was 0.66 (p = 0.02), which is notable given typical test-retest reliability of IQ measurement.
Evidently, a robust correlational link exists between efficient processing of sensory information and intelligence. These results are, to the best of our knowledge, the strongest link between IQ and perceptual discriminations (links with traditional inspection time measurements rarely exceed 0.3). One possibility is that utilization of duration threshold measurements as an index of perceptual information accumulation speed provides a more accurate glimpse into the processes shared by sensory and cognitive systems.
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