This set of data consists of primarily questionnaire data, part of a larger collection of data considering differences in visual memory, visual ability, and the diagnosis of sequence-space synaesthesia. Several studies have suggested that there is a link between synaesthesia and autism but the nature of that link remains poorly characterised. The present study considers whether atypical sensory sensitivity may be a common link between the conditions. Sensory hypersensitivity (aversion to certain sounds, touch, etc., or increased ability to make sensory discriminations) and/or hyposensitivity (e.g., desire to stimulate the senses, or a reduced response to sensory stimuli) are a recently introduced diagnostic feature of autism spectrum conditions (ASC). Synaesthesia is defined by unusual sensory experiences and has also been linked to atypical cortical hyper-excitability. The Glasgow Sensory Questionnaire (GSQ) was administered to synaesthetes and people with ASC. Both groups reported increased sensory sensitivity relative to controls with a large effect size. Both groups also reported a similar pattern of both increased hyper- and hypo-sensitivities across multiple senses. The AQ (Autism-Spectrum Quotient) scores were elevated in the synaesthetes, and one subscale of this measure (attention to detail) placed synaesthetes within the autistic range. A standard laboratory test of visual stress (the Pattern Glare Test), administered online, corroborated the findings of increased sensitivity to aversive visual stimuli in synaesthetes. Atypical sensory sensitivity is an important shared feature between autism and synaesthesia. In this research programme we will investigate enhanced memory in synaesthesia (e.g. experiencing colours for words). Our general approach is to treat synaesthesia as a 'test case' to address other important research questions. For instance, we consider how synaesthesia can inform general theories of memory. Importantly, not all aspects of memory are enhanced in synaesthesia and this can provide insights into how the memory system is structured. Indeed it is not trivially the case that material that elicits 'extra' sensations are better remembered: some material that does not evoke extra sensations (such as abstract figures) are also better remembered by synaesthetes. We suggest that synaesthetes have widespread changes in their perceptual systems (including but not limited to their extra experiences) and that systems supporting perception can also be engaged in memory. We will use both standard and bespoke tests of memory to explore which aspects of memory are enhanced and we will explore how individual differences in perception (in non-synaesthetes) may relate to performance on certain memory tasks.

Two questionnaires and an experiment test of visual sensitivity.