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                 | Out of sight, out of mind: Suppression of synaesthetic colours during the attentional blink Rich A.N.1,2 Mattingley, J.B.2 1 Visual Attention Laboratory, Brigham & Women’s Hospital/Harvard Medical School, MA, USA 2 Cognitive Neuroscience Laboratory, School of Behavioural Science, University of Melbourne, Victoria, Australia
Mailing address: Visual Attention Laboratory
Synaesthesia is an unusual phenomenon that is often described as a ‘mixing of the senses’. In its most common form, letters elicit consistent experiences of colour. These colours arise relatively automatically: synaesthetes show Stroop-type interference when naming the display colour of letters that elicit incongruent versus congruent synaesthetic colours. Using a modified ‘attentional blink’ (AB) paradigm, we tested whether selective attention to the inducing letter is required for synaesthetic colours to be elicited. In a classic AB task, two targets are presented within a rapid stream of distractors. Participants typically miss the second target (T2) when it follows the initial target (T1) within ~500 ms. This ‘attentional blink’ is thought to arise from the processing demands of T1, which reduce the availability of attentional resources for consolidating the representation of T2. We tested whether letters presented during the AB elicited synaesthetic Stroop interference despite being less available for conscious report. Twelve synaesthetes and matched non-synaesthetic controls participated. On each trial, T1 was a white grating in a stream of grey, non-letter distractors. On 50% of trials, a grey letter (T2) was presented among the distractors. At the end of each stream a coloured probe appeared, and participants named the colour as quickly as possible. The synaesthetic colour elicited by the T2 letter could be congruent or incongruent with the subsequent coloured probe. When attending to the T2 letter (reporting the presence of the letter only), synaesthetes were slower to name the probe colour on incongruent versus congruent trials, demonstrating a robust synaesthetic Stroop effect. In contrast, when participants were asked to report T1 and name the colour, ignoring the T2 letter, there was a critical time point during the AB where the synaesthetic Stroop effect was eliminated. When T2 followed T1 by 350 ms, there was no effect of synaesthetic congruency. There were significant synaesthetic effects at both earlier and later time points, suggesting that the requirement for attentive processing of an inducer may be time dependent. These results have implications for our understanding of both synaesthesia and the attentional blink. |