Diagnosing synaesthesia with online colour pickers: Maximising sensitivity and specificity

Rothen, Nicolas; Seth, Anil K.; Witzel, Christoph; Ward, Jamie

doi:10.1016/j.jneumeth.2013.02.009

Cited by 122 publications

(163 citation statements)

References 13 publications

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“…Inducer-concurrent consistency is a widely used, and highly robust, diagnostic marker of congenital synaesthesia (Eagleman et al, 2007;Rothen et al, 2013). In the present study, grapheme-and sound-colour associations did not differ in consistency across LSD and placebo conditions, with associations being actually numerically less consistent in the former condition, a result that is strongly at odds with the hypothesis that LSD is producing consistent synaesthesia-like experiences.…”

Section: Discussioncontrasting

confidence: 80%

“…If LSD was inducing genuine synaesthesia, one might expect that grapheme-colour and sound-colour associations would be more consistent under LSD in comparison with placebo, as is observed in congenital synaesthetes relative to non-synaesthete controls (Eagleman et al, 2007;Rothen et al, 2013).…”

Section: Grapheme-colour and Sound-colour Consistencymentioning

confidence: 99%

“…This measure is computed by averaging the geometric distance in RGB colour space for RGB values for each pair of stimuli presented across the two blocks in the sound and colour tasks (see also Rothen, Seth, Witzel, & Ward, 2013). Lower values reflect less colour distance across stimulus presentations and thus greater stimulus-colour consistency.…”

Section: Stimulus-colour Consistencymentioning

confidence: 99%

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A placebo-controlled investigation of synaesthesia-like experiences under LSD

et al. 2016

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The induction of synaesthesia in non-synaesthetes has the potential to illuminate the mechanisms that contribute to the development of this condition and the shaping of its phenomenology. Previous research suggests that lysergic acid diethylamide (LSD) reliably induces synaesthesia-like experiences in nonsynaesthetes. However, these studies suffer from a number of methodological limitations including lack of a placebo control and the absence of rigorous measures used to test established criteria for genuine synaesthesia. Here we report a pilot study that aimed to circumvent these limitations. We conducted a within-groups placebo-controlled investigation of the impact of LSD on colour experiences in response to standardized graphemes and sounds and the consistency and specificity of grapheme-and sound-colour associations. Participants reported more spontaneous synaesthesia-like experiences under LSD, relative to placebo, but did not differ across conditions in colour experiences in response to inducers, consistency of stimulus-colour associations, or in inducer specificity. Further analyses suggest that individual differences in a number of these effects were associated with the propensity to experience states of absorption in one's daily life. Although preliminary, the present study suggests that LSD-induced synaesthesia-like experiences do not exhibit consistency or inducer-specificity and thus do not meet two widely established criteria for genuine synaesthesia.

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Section: Discussioncontrasting

confidence: 80%

Section: Grapheme-colour and Sound-colour Consistencymentioning

confidence: 99%

Section: Stimulus-colour Consistencymentioning

confidence: 99%

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A placebo-controlled investigation of synaesthesia-like experiences under LSD

et al. 2016

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“…Lower scores reflect higher consistency. Consistency was also calculated using the same formula by converting RGB values into CIELUV colour space, as this measure has been shown to have greater sensitivity and specificity relative to RGB space consistency (Rothen, Seth, Witzel & Ward, 2013)…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…Thus, our experimental hypothesis is supported. The difference between RGB and CIELUV consistency for AW is likely to be due to consistency measures based M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 3 on perceptual CIELUV colour models providing greater sensitivity and specificity than RGB consistency (Rothen et al, 2013).…”

Section: [Two-panel Figure]mentioning

confidence: 99%

Timbre-colour synaesthesia: Exploring the consistency of associations based on timbre

Menouti

Akiva-Kabiri

Banissy

2015

Cortex

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The chemical induction of synaesthesia

Luke

Lungu

Friday

et al. 2022

Human Psychopharmacology

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Objective: Preliminary research suggests that experiences resembling synaesthesia are frequently reported under the influence of a diverse range of chemical substances although the incidence, chemical specificity, and characteristics of these effects are poorly understood.Methods: Here we surveyed recreational drug users and self-reported developmental synaesthetes regarding their use of 28 psychoactive drugs from 12 different drug classes and whether they had experienced synaesthesia under the influence of these substances. Results:The drug class of tryptamines exhibited the highest incidence rates of druginduced synaesthesia in controls and induction rates of novel forms of synaesthesia in developmental synaesthetes. Induction incidence rates in controls were strongly correlated with the corresponding induction and enhancement rates in developmental synaesthetes. In addition, the use of lysergic acid diethylamide (LSD) was the strongest predictor of drug-induced synaesthesia in both controls and developmental synaesthetes. Clear evidence was observed for a clustering of synaesthesiainduction rates as a function of drug class in both groups, denoting non-random incidence rates within drug classes. Sound-colour synaesthesia was the most commonly observed type of induced synaesthesia. Further analyses suggest the presence of synaesthesia-prone individuals, who were more likely to experience drug-induced synaesthesia with multiple drugs.Conclusions: These data corroborate the hypothesized link between drug-induced synaesthesia and serotoninergic activity, but also suggest the possibility of alternative neurochemical pathways involved in the induction of synaesthesia. They further imply that the induction and modulation of synaesthesia in controls and developmental synaesthetes share overlapping mechanisms and that certain individuals may be more susceptible to experiencing induced synaesthesia with different drugs.

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Diagnosing synaesthesia with online colour pickers: Maximising sensitivity and specificity

Cited by 122 publications

References 13 publications

A placebo-controlled investigation of synaesthesia-like experiences under LSD

A placebo-controlled investigation of synaesthesia-like experiences under LSD

Timbre-colour synaesthesia: Exploring the consistency of associations based on timbre

The chemical induction of synaesthesia

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