Reflections on Synesthesia, Perception, and Cognition

Abstract

Réflexions sur la synesthésie, la perception et la cognition. Nous nous penchons dans cet article sur trois questions toujours actuelles : sur le rapport entre le monde physique et le monde perçu, sur la difficulté d’expliquer les différences individuelles dans la perception du monde environnant, et sur l’énigme de la compréhension de l’esprit d’autrui. En examinant la relation entre la synesthésie et les hallucinations, et entre les hallucinations et la perception normale, nous montrons que tous ces phénomènes ont bien plus en commun qu’on ne le supputait. Nous nous interrogeons ensuite sur la plausibilité d’une analyse fonctionnelle de la synesthésie, et examinons les mécanismes de différents types de perception ordinaire et extraordinaire. Nous soutenons que des mécanismes de même type que ceux impliqués dans les synesthésies pourraient intervenir tout un éventail de phénomènes perceptifs et cognitifs, et montrons l’utilité d’une telle approche eu égard à l’ubiquité dans la cognition humaine des processus qui formellement rappellent la synesthésie.

Serotonergic Hyperactivity as a Potential Factor in Developmental, Acquired and Drug-Induced Synesthesia

“…Subjects report seeing melting windows, breathing walls and spiraling geometrical figures crawling over the surfaces of objects. Reflecting on a DMT session one subject, described by Cott and Rock (2008), reported that “The room erupted in incredible neon colors, and dissolving into the most elaborate incredibly detailed fractal patterns that I have ever seen.” The authors characterize this as a hallucination, and it is admittedly difficult to distinguish synesthesia and hallucinations, particularly because some forms of synesthesia probably are best characterized as hallucinations (Sagiv et al, 2011). A crucial difference seems to be that hallucinations proper do not have a phenomenally apparent inducer, whereas synesthesia does.…”

“…A common synesthetic experience during hallucinogen intoxication is colored, geometrical grids, matrices or fractals induced by music (see Sinke et al, 2012 for a review). These types of visual experience also frequently occur without an inducer, probably as a result of random activity in the thalamus (Behrendt and Young, 2004; Sagiv et al, 2011). One possible mechanism for drug-induced synesthesia, then, is that the brain assumes that an experience that results from occipital processing of random thalamic activity matches auditory stimuli, leading to an unusual low-level binding in the auditory cortex (see Figure 2 ).…”

When synesthesia and savant abilities are mistaken for hallucinations and delusions: contribution of a cognitive approach for their differential diagnosis

“…This idea has already been mentioned in the literature (Pearson & Westbrook, 2015;Sagiv, Ilbeigi, & Ben-Tal, 2011), but there is no research that further illustrates the distinctions between synesthesia and hallucinations. At the cognitive level, synesthesia is characterized by superior Can VA's astrophysical reasoning be considered a savant ability?…”

“…After noting the crossover between synesthesia and hallucinations, Sagiv et al (2011) reported the similarities between the two phenomena. Indeed, both are subjective, occur in the absence of an appropriate stimulus, and are not under voluntary control.…”

Creating Colored Letters: Familial Markers of Grapheme–Color Synesthesia in Parietal Lobe Activation and Structure

“…Synesthesia is informative because it provides an opportunity to understand how an additional experience like color arises in the absence of the external input corresponding to wavelengths of light. Synesthetic experiences are distinct from hallucinations (Sagiv, Ilbeigi, & Ben-Tal, 2011;Cytowic, 2002), and developmental synesthesia is normally present in the absence of pathology (Cytowic, 2002;Baron-Cohen & Harrison, 1997).…”