Visually perceiving odour: insights into olfactory synaesthesia
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1
Macquarie University, Department of Cognitive Science, Australia
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2
University of Sydney, School of Psychology, Australia
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3
Macquarie University, Department of Psychology, Australia
Background:
In synaesthesia, a stimulus in one modality elicits an unusual experience within the same, or in another, modality. We examined olfactory synaesthetes for whom odours elicit visual experiences. There are very few studies of olfactory synaesthesia, but it could provide insight into the debate regarding the role of meaning in synaesthesia. Odours are often difficult to identify, which gives the potential to disentangle full identification from awareness of characteristics of the stimulus, allowing examination of the relationship between inducer processing and synaesthetic experience.
Methods:
We tested 6 synaesthetes who reported visual experiences in response to odours. We documented their responses to 20 odours (varying in intensity, irritancy, hedonics, familiarity, and ease of naming) over 2 sessions. We tested the consistency of reports over time, and the characteristics of images across the range of odours. We assessed the consistency of the complex visual images via similarity judgements from 20 non-synaesthetic raters, as well as collecting normative data (non-synaesthetes).
Results:
Synaesthetes were significantly better at identifying odours than non-synaesthetes. Both groups showed highly reliable ratings of intensity, hedonics, irritancy, and familiarity. Similarity ratings demonstrated that the synaesthetes’ complex visual images from odours were consistent over time. For the same odour, named consistently at times 1 and 2, the synaesthete images were more similar than images from different odours, and also from the same odour named differently on the 2 sessions. Images from the same odour named differently were also more similar than from 2 different odours. This latter finding held even when we separated similarity by near and far misses: when an odour was named quite differently on the 2 occasions, the image generated was more similar than for 2 different odours. Further analyses on the other attributes of the odours show this ‘nameless’ effect is due to consistent hedonic information.
Discussion:
These results demonstrate that the complex visual images elicited by odours for olfactory synaesthetes are consistent and correlate with improved odour identification relative to controls. They suggest that these visual experiences are elicited by access to the meaning of the odour – primarily through identifying a name, but with a contribution from non-linguistic semantic information carried in the hedonic qualities of an odour.
Acknowledgements
This research was supported by a Macquarie University Research Development Grant to ANR and RS. ANR was supported by the Australian Research Council (APD+DP0984494).
Keywords:
Olfaction,
synaesthesia,
multisensory integration,
multisensory perception,
Consistency,
level of inducer processing
Conference:
ACNS-2013 Australasian Cognitive Neuroscience Society Conference, Clayton, Melbourne, Australia, 28 Nov - 1 Dec, 2013.
Presentation Type:
Oral
Topic:
Sensation and Perception
Citation:
Rich
AN,
Russell
AM and
Stevenson
R
(2013). Visually perceiving odour: insights into olfactory synaesthesia.
Conference Abstract:
ACNS-2013 Australasian Cognitive Neuroscience Society Conference.
doi: 10.3389/conf.fnhum.2013.212.00169
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Received:
15 Oct 2013;
Published Online:
25 Nov 2013.
*
Correspondence:
Dr. Anina N Rich, Macquarie University, Department of Cognitive Science, Sydney, NSW, 2109, Australia, anina.rich@mq.edu.au