Behavioral scientists routinely publish broad claims about human psychology and behavior in the world's top journals based on samples drawn entirely from Western, Educated, Industrialized, Rich, and Democratic (WEIRD) societies. Researchers – often implicitly – assume that either there is little variation across human populations, or that these “standard subjects” are as representative of the species as any other population. Are these assumptions justified? Here, our review of the comparative database from across the behavioral sciences suggests both that there is (...) substantial variability in experimental results across populations and that WEIRD subjects are particularly unusual compared with the rest of the species – frequent outliers. The domains reviewed include visual perception, fairness, cooperation, spatial reasoning, categorization and inferential induction, moral reasoning, reasoning styles, self-concepts and related motivations, and the heritability of IQ. The findings suggest that members of WEIRD societies, including young children, are among the least representative populations one could find for generalizing about humans. Many of these findings involve domains that are associated with fundamental aspects of psychology, motivation, and behavior – hence, there are no obviousa priorigrounds for claiming that a particular behavioral phenomenon is universal based on sampling from a single subpopulation. Overall, these empirical patterns suggests that we need to be less cavalier in addressing questions ofhumannature on the basis of data drawn from this particularly thin, and rather unusual, slice of humanity. We close by proposing ways to structurally re-organize the behavioral sciences to best tackle these challenges. (shrink)

We investigated grapheme-colour synaesthesia and found that The induced colours led to perceptual grouping and pop-out, a number rendered invisible through 'crowding' or lateral masking can induce synaesthetic colours -- a form of blindsight -- and peripherally presented graphemes did not induce colours even when they were clearly visible. Taken collectively, these and other experiments prove conclusively that synaesthesia is a genuine perceptual phenomenon, not an effect based on memory associations from childhood or on vague metaphorical speech. We identify different (...) subtypes of number-colour synaesthesia and propose that they are caused by hyperconnectivity between colour and number areas at different stages in processing; lower synaesthetes may have cross-wiring within the fusiform gyrus whereas higher synaesthetes may have cross-activation in the angular gyrus. This hyperconnectivity might be caused by a genetic mutation that causes defective pruning of connections between brain maps. The mutation may further be expressed selectively in the fusiform or angular gyri, and this may explain the existence of different forms of synaesthesia. If expressed very diffusely, there may be extensive cross-wiring between brain regions that represent abstract concepts, which would explain the link between creativity, metaphor and synaesthesia. Also, hyperconnectivity between the sensory cortex and amygdala would explain the heightened aversion synaesthetes experience when seeing numbers printed in the 'wrong' colour. Lastly, kindling -- induced hyperconnectivity in the temporal lobes of temporal lobe epilepsy patients -- may explain the purported higher incidence of synaesthesia in these patients. We conclude with a synaesthesia-based theory of the evolution of language. Thus, our experiments on synaesthesia and our theoretical framework attempt to link several seemingly unrelated facts about the human mind. Far from being a mere curiosity, synaesthesia may provide a window into perception, thought and language. (shrink)

(1) The induced colours led to perceptual grouping and pop-out, (2) a grapheme rendered invisible through ‘crowding’ or lateral masking induced synaesthetic colours — a form of blindsight — and (3) peripherally presented graphemes did not induce colours even when they were clearly visible. Taken collectively, these and other experiments prove conclusively that synaesthesia is a genuine percep- tual phenomenon, not an effect based on memory associations from childhood or on vague metaphorical speech. We identify different subtypes of number–colour synaesthesia (...) and propose that they are caused by hyperconnectivity between col- our and number areas at different stages in processing; lower synaesthetes may have cross-wiring (or cross-activation) within the fusiform gyrus, whereas higher synaesthetes may have cross-activation in the angular gyrus. This hyperconnec- tivity might be caused by a genetic mutation that causes defective pruning of con- nections between brain maps. The mutation may further be expressed selectively (due to transcription factors) in the fusiform or angular gyri, and this may explain the existence of different forms of synaesthesia. If expressed very diffusely, there may be extensive cross-wiring between brain regions that represent abstract concepts, which would explain the link between creativity, metaphor and synaesthesia (and the higher incidence of synaesthesia among artists and poets). Also, hyperconnectivity between the sensory cortex and amygdala would explain the heightened aversion synaesthetes experience when seeing numbers printed in the ‘wrong’ colour. Lastly, kindling (induced hyperconnectivity in the temporal lobes of temporal lobe epilepsy [TLE] patients) may explain the purported higher incidence of synaesthesia in these patients. We conclude with a synaesthesia-based theory. (shrink)

For more than a century now, researchers have acknowledged the existence of seemingly arbitrary crossmodal congruency effects between dimensions of sensory stimuli in the general population. Such phenomena, known by a variety of terms including 'crossmodal correspondences', involve individual stimulus properties, rely on a crossmodal mapping of unisensory features, and appear to be shared by the majority of individuals. In other words, members of the general population share underlying preferences for specific pairings across the senses. Crossmodal correspondences between complementary sensory (...) cues have often been referred to as synesthetic correspondences but, we would argue, differ from full-blown synesthetic experiences in a number of important ways, including the fact that there are no idiosyncratic concurrent sensations. Recent psychophysical evidence suggests that such crossmodal correspondences can modulate multisensory integration by helping to resolve the crossmodal binding problem. Here, we propose a model to account for the effects of crossmodal correspondences between complementary auditory and visual cues and critically review their relation to full-blown synesthesia. (shrink)

Color conveys critical information about the flavor of food and drink by providing clues as to edibility, flavor identity, and flavor intensity. Despite the fact that more than 100 published papers have investigated the influence of color on flavor perception in humans, surprisingly little research has considered how cognitive and contextual constraints may mediate color–flavor interactions. In this review, we argue that the discrepancies demonstrated in previously-published color–flavor studies may, at least in part, reflect differences in the sensory expectations that (...) different people generate as a result of their prior associative experiences. We propose that color–flavor interactions in flavor perception cannot be understood solely in terms of the principles of multisensory integration but that the role of higher-level cognitive factors, such as expectations, must also be considered. (shrink)

Our understanding of the sense of taste is largely based on research designed and interpreted in terms of the traditional four tastes: sweet, sour, salty, and bitter, and now a few more. This concept of basic tastes has no rational definition to test, and thus it has not been tested. As a demonstration, a preliminary attempt to test one common but arbitrary psychophysical definition of basic tastes is included in this article; that the basic tastes are unique in being able (...) to account for other tastes. This definition was falsified in that other stimuli do about as well as the basic words and stimuli. To the extent that this finding might show analogies with other studies of receptor, neural, and psychophysical phenomena, the validity of the century-long literature of the science of taste based on a few is called into question. The possible origins, meaning, and influence of this concept are discussed. Tests of the model with control studies are suggested in all areas of taste related to basic tastes. As a stronger alternative to the basic tradition, the advantages of the across-fiber pattern model are discussed; it is based on a rational data-based hypothesis, and has survived attempts at falsification. Such has found broad acceptance in many neural systems. (shrink)

Weak synesthesia refers to the recognition of similarities or correspondences across different domains of sensory, affective, or cognitive experience - for example, the similarity between increasingly high-pitched sounds and increasingly bright lights. Strong synesthesia, in contrast, refers to the actual arousal of experiences in another domain, as when musical notes evoke colors. Whereas various forms of strong synesthesia characterize mental life in a relatively small portion of population, weak synesthesia is far more pervasive, in some instances virtually universal. Several examples (...) of cross-modal similarity, such as pitch-brightness, appear in early childhood, even infancy, consistent with the hypothesis that they are intrinsic to sensory processing, although even early cross-modal similarities might be learned through exposure to correlated sensory events. Beyond perception, weak synesthesia reveals itself notably the production and understanding of cross-modal metaphors, found in both everyday and literary language. The comprehension of synesthetic metaphors by both children and adults often parallels cross-modal similarities in perception. It is likely that, whatever their source, many cross-modal similarities, perhaps most of them, begin in perception and then become available to language. The evidence that preschool-aged children can perceive cross-sensory resemblances and comprehend cross-sensory metaphors is consistent with the hypothesis that mechanisms underlying weak synesthesia play a significant role in the ontogeny of metaphor comprehension and metaphor creation more generally. Theories of embodied cognition, which treat mind as embedded in body and bodily action, may provide a useful framework for understanding metaphor in general and synesthetic metaphor in particular. (shrink)