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Synaesthetic colours do not camouflage form in visual search.

Gheri C, Chopping S, Morgan MJ - Proc. Biol. Sci. (2008)

Bottom Line: As well as using a condition where synaesthetic colours should have aided visual search, we introduced a condition where the colours experienced by synaesthetes would be expected to make them worse than controls.We found no evidence for differences between synaesthetes and normal controls, either when colours should have helped them or where they should have hindered.We conclude that the colours reported by our population of synaesthetes are not equivalent to perceptual signals, but arise at a cognitive level where they are unable to affect visual search.

View Article: PubMed Central - PubMed

Affiliation: Applied Vision Research Centre, The City University, Northampton Square, London ECV1 0HB, UK.

ABSTRACT
One of the major issues in synaesthesia research is to identify the level of processing involved in the formation of the subjective colours experienced by synaesthetes: are they perceptual phenomena or are they due to memory and association learning? To address this question, we tested whether the colours reported by a group of grapheme-colour synaesthetes (previously studied in an functional magnetic resonance imaging experiment) influenced them in a visual search task. As well as using a condition where synaesthetic colours should have aided visual search, we introduced a condition where the colours experienced by synaesthetes would be expected to make them worse than controls. We found no evidence for differences between synaesthetes and normal controls, either when colours should have helped them or where they should have hindered. We conclude that the colours reported by our population of synaesthetes are not equivalent to perceptual signals, but arise at a cognitive level where they are unable to affect visual search.

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Related in: MedlinePlus

Example of the stimulus array. In this test, all the numbers of the matrix were black (0.8°×0.5°; total stimulus size 4.5°×4.8°; spacing between numbers 1°). The task was indicating the location of the unique number. Two conditions were programmed depending on which colour subjects would associate to each number: the unique one, where the target was the only item with a certain colour and the non-unique condition where the perceived target colour was repeated on different numbers.
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fig1: Example of the stimulus array. In this test, all the numbers of the matrix were black (0.8°×0.5°; total stimulus size 4.5°×4.8°; spacing between numbers 1°). The task was indicating the location of the unique number. Two conditions were programmed depending on which colour subjects would associate to each number: the unique one, where the target was the only item with a certain colour and the non-unique condition where the perceived target colour was repeated on different numbers.

Mentions: The stimulus array was a 4×4 matrix of different numerals (figure 1) presented in the centre on the screen. The numbers presented were all black and they were all repeated at least once except for the target. (e.g. in the set 3 6 6 7 6 7 5 6 3 7 5 6 3 5 7 8, the number 8 is the target). Two conditions were contrasted for synaesthetes. In the first (the ‘unique condition’) condition, the numbers for each synaesthetic subject were chosen such that the target, as well as being a unique number, also had a unique subjective colour for that subject. In other words, all the distracters had the same subjective colour for that subject, which was different from the colour of the target. In the second condition (‘non-unique’), the target shared its subjective colour with that of at least one of the distracters. Every synaesthete was paired with an age-matched control who was presented with exactly the same stimuli, in the same order. The unique and non-unique conditions were randomly interleaved, and 60 trials were collected in each condition. Constraints on the availability of differently coloured numbers for the synaesthetes meant that the unique condition could contain only five different numbers, while the non-unique contained six different numbers.


Synaesthetic colours do not camouflage form in visual search.

Gheri C, Chopping S, Morgan MJ - Proc. Biol. Sci. (2008)

Example of the stimulus array. In this test, all the numbers of the matrix were black (0.8°×0.5°; total stimulus size 4.5°×4.8°; spacing between numbers 1°). The task was indicating the location of the unique number. Two conditions were programmed depending on which colour subjects would associate to each number: the unique one, where the target was the only item with a certain colour and the non-unique condition where the perceived target colour was repeated on different numbers.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2366133&req=5

fig1: Example of the stimulus array. In this test, all the numbers of the matrix were black (0.8°×0.5°; total stimulus size 4.5°×4.8°; spacing between numbers 1°). The task was indicating the location of the unique number. Two conditions were programmed depending on which colour subjects would associate to each number: the unique one, where the target was the only item with a certain colour and the non-unique condition where the perceived target colour was repeated on different numbers.
Mentions: The stimulus array was a 4×4 matrix of different numerals (figure 1) presented in the centre on the screen. The numbers presented were all black and they were all repeated at least once except for the target. (e.g. in the set 3 6 6 7 6 7 5 6 3 7 5 6 3 5 7 8, the number 8 is the target). Two conditions were contrasted for synaesthetes. In the first (the ‘unique condition’) condition, the numbers for each synaesthetic subject were chosen such that the target, as well as being a unique number, also had a unique subjective colour for that subject. In other words, all the distracters had the same subjective colour for that subject, which was different from the colour of the target. In the second condition (‘non-unique’), the target shared its subjective colour with that of at least one of the distracters. Every synaesthete was paired with an age-matched control who was presented with exactly the same stimuli, in the same order. The unique and non-unique conditions were randomly interleaved, and 60 trials were collected in each condition. Constraints on the availability of differently coloured numbers for the synaesthetes meant that the unique condition could contain only five different numbers, while the non-unique contained six different numbers.

Bottom Line: As well as using a condition where synaesthetic colours should have aided visual search, we introduced a condition where the colours experienced by synaesthetes would be expected to make them worse than controls.We found no evidence for differences between synaesthetes and normal controls, either when colours should have helped them or where they should have hindered.We conclude that the colours reported by our population of synaesthetes are not equivalent to perceptual signals, but arise at a cognitive level where they are unable to affect visual search.

View Article: PubMed Central - PubMed

Affiliation: Applied Vision Research Centre, The City University, Northampton Square, London ECV1 0HB, UK.

ABSTRACT
One of the major issues in synaesthesia research is to identify the level of processing involved in the formation of the subjective colours experienced by synaesthetes: are they perceptual phenomena or are they due to memory and association learning? To address this question, we tested whether the colours reported by a group of grapheme-colour synaesthetes (previously studied in an functional magnetic resonance imaging experiment) influenced them in a visual search task. As well as using a condition where synaesthetic colours should have aided visual search, we introduced a condition where the colours experienced by synaesthetes would be expected to make them worse than controls. We found no evidence for differences between synaesthetes and normal controls, either when colours should have helped them or where they should have hindered. We conclude that the colours reported by our population of synaesthetes are not equivalent to perceptual signals, but arise at a cognitive level where they are unable to affect visual search.

Show MeSH
Related in: MedlinePlus