Mary Jane Spiller

Mental imagery and synaesthesia: Is synaesthesia from internally-generated stimuli possible?

Previous studies provide empirical support for the reported colour experience in grapheme-colour synaesthesia by measuring the synaesthetic experience from an externally presented grapheme. The current study explored the synaesthetic experience resulting from a visual mental image of a grapheme. Grapheme-colour synaesthetes (N=6) and matched controls (N=10 per synaesthete) completed a visual mental imagery task that involved visualising a letter and making a size-based decision about it. The background colour that the grapheme was visualised against was manipulated so that it was congruent or incongruent with the synaesthetic colour for the grapheme being visualised. Compared to matched controls, an effect of colour condition was found for four of the six synaesthetes, although importantly the direction of the effect varied between synaesthetes. In addition, a significant effect of group was found, as the synaesthetes were all faster than the matched controls at the imagery task, regardless of background colour. We conclude that there is some support for subjective reports of imagery-induced synaesthesia, but there are important individual differences. These findings are discussed in relation to both the visual imagery and synaesthesia literature.

Low secure units: Factors predicting delayed discharge

Abstract Previous research has shown that around one-third of inpatients in high secure units are in a level of security incommensurate with their actual need. In this article we show that in a cohort of 200 inpatients in low secure units in a region of England, one third were assumed to be in an inappropriate level of security; most of these were thought to require a lower level. The characteristics of this cohort are described. Logistic regression was used to find variables that could predict whether an inpatient required a lower level of security. Due to interactions between the two types of unit included in this study (mental health units and learning disabilities * units) two separate models were produced, showing different predictive variables for each type of unit. For those in mental health units, being female and not being a risk to others predicted a need for a lower level of security, and for those in learning disabilities units, being younger and being admitted on an informal basis were predictive. The results are discussed in relation to their implications for service development. *‘Learning disabilities’ is the term used in the UK for ‘mental retardation’ (ICD-10 F70–F79)

Comparing implicit and synaesthetic number–space associations: Visuospatial and verbal spatial–numerical associations of response codes

In the theory of the mental number line, number, and space are implicitly associated, giving rise to the spatial–numerical association of response codes (SNARC) effect, in which smaller numbers are more readily associated with the left side of space and larger numbers with the right, during a parity judgement task. Others, however, have argued that the SNARC effect is flexible and better explained by verbal rather than spatial associations. A few single-case studies on the SNARC effect have tested number–space synaesthetes, who make explicit associations between number and space. Here, we present data from experiments conducted on groups of synaesthetes and nonsynaesthetes on the classic SNARC parity judgement task with lateralized response keys and a modified version in which they responded to labels appearing on screen. Synaesthetes’ behaviour was expected to differ from nonsynaesthetes’ behaviour due to the explicit, fixed nature of their number–space associations, but both experiments show the two groups behaving in the same way, indicating that parity judgement tasks may not be tapping the same representation of number that gives rise to synaesthetic number–space experiences.

Summation of visual attributes in auditory–visual crossmodal correspondences

Crossmodal correspondences are a feature of human perception in which two or more sensory dimensions are linked together; for example, high-pitched noises may be more readily linked with small than with large objects. However, no study has yet systematically examined the interaction between different visual–auditory crossmodal correspondences. We investigated how the visual dimensions of luminance, saturation, size, and vertical position can influence decisions when matching particular visual stimuli with high-pitched or low-pitched auditory stimuli. For multidimensional stimuli, we found a general pattern of summation of the individual crossmodal correspondences, with some exceptions that may be explained by Garner interference. These findings have applications for the design of sensory substitution systems, which convert information from one sensory modality to another.

Introduction to the Special Issue on Individual Differences in Multisensory Perception: An Overview

The world is full of objects that can be perceived through multiple different senses to create an integrated understanding of our environment. Since each of us has different biological and psychological characteristics, different people may perceive the world in quite different ways. However, the questions of how and why our multisensory perceptions differ have not been explored in any great depth. This special issue, arising from a series of British Psychological Society-funded seminars, presents new research and opinions on the impacts of a variety of individual differences on multisensory perception. We hope that readers will enjoy this collection of eight papers on individual differences in multisensory perception arising from developmental changes, autism, Down syndrome, migraine, sensory loss and substitution, and personality.

Auditory and Visual Crossmodal Correspondences With Haptically Perceived Liquid Viscosity

Past research on cross-modal correspondences as they relate to tactile perception has largely been restricted to solid substances. We investigated the role of haptically explored liquid viscosity in crossmodal correspondences with visually presented luminance, saturation, roundedness, size, number and visual elevation, as well as pure-tone pitch and kiki-bouba-type letter strings. In Experiment 1, we presented two tactile and two visual or auditory stimuli simultaneously, and found significant inter-participant agreement (N = 32) when pairing viscosity with luminance, saturation, roundedness, size, pitch and letter string type. To assess whether these crossmodal correspondences were relative or absolute, another 32 participants were presented, in Experiment 2, with two tactile stimuli but only one visual/auditory stimulus per trial. In this second Experiment, we found that high viscosity was paired with low luminance, roundness, low saturation, and the bouba-type letter string, while low viscosity was paired with high pitch. However, the inverse associations (e.g. low viscosity with high luminance, high viscosity with low pitch) were not significant. These findings indicate that viscosity can be added to the list of dimensions that invoke crossmodal correspondences, and that the majority of crossmodal correspondences involving viscosity are absolute rather than relative, since they appear without explicit comparisons along the visual/auditory dimensions we measured.

Exploring synaesthetes’ mental imagery abilities across multiple sensory modalities

Previous research on the mental imagery abilities of synaesthetes has concentrated on visual and spatial imagery in synaesthetes with spatial forms (Price, 2009, 2010; Simner et al., 2008) and letter-colour synaesthesia (Spiller and Jansari, 2008). Though Barnett and Newell (2008) asked synaesthetes of all types to fill out a questionnaire on visual imagery, most of their synaesthetes reported some form of linguistic–colour synaesthesia. We extend the investigation of mental imagery to a wider variety of synaesthesia types and a wider variety of sensory modalities using a questionnaire study and several tests of visual and auditory mental imagery ability. Our results indicate that, as a group, synaesthetes report making greater use of mental imagery than non-synaesthetes, in everyday activities. Furthermore, they self-report greater vividness of visual, auditory, tactile, and taste imagery than do non-synaesthetes. However, as a group the synaesthetes are not seen to do significantly better at the mental imagery tasks, in either the visual or auditory modalities. These results have important implications for our understanding of synaesthesia, in relation to potential fundamental differences in perceptual processing of synaesthetes and non-synaesthetes.