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James E. A. Hughes, Julia Simner, Simon Baron-Cohen, Darold A. Treffert and Jamie Ward

Savant syndrome is a condition where prodigious talent co-occurs with developmental difficulties such as autism spectrum conditions (ASC). To better understand savant skills, we previously proposed a link with synaesthesia: that savant syndrome may arise in ASC individuals who also happen to have synaesthesia. A second, unrelated claim is that people with autism may have higher rates of synaesthesia. Here we ask whether synaesthesia is indeed found more often in autism per se, or only in cases where autism co-occurs with savant skills. People with autism in previous studies when tested for synaesthesia were not differentiated into those with and without savant abilities. Here we tested three groups: people with autism who also have savant skills (n=40), people with autism without savant skills (n=34), and controls without autism (n=29). We used a validated test to diagnose grapheme–colour synaesthesia. Results show a significantly higher prevalence of synaesthesia in people with ASC, but only those who also have savant skills. This suggests that synaesthesia in autism is linked to those with savant abilities rather than autism per se. We discuss the role of synaesthesia in the development of prodigious talent.

Thomas U. Otto and Pascal Mamassian

The use of separate multisensory signals is often beneficial. A prominent example is the speed-up of responses to two redundant signals relative to the components, which is known as the redundant signals effect (RSE). A convenient explanation for the effect is statistical facilitation, which is inherent in the basic architecture of race models (Raab, 1962, Trans. N. Y. Acad. Sci. 24, 574–590). However, this class of models has been largely rejected in multisensory research, which we think results from an ambiguity in definitions and misinterpretations of the influential race model test (Miller, 1982, Cogn. Psychol. 14, 247–279). To resolve these issues, we here discuss four main items. First, we clarify definitions and ask how successful models of perceptual decision making can be extended from uni- to multisensory decisions. Second, we review the race model test and emphasize elements leading to confusion with its interpretation. Third, we introduce a new approach to study the RSE. As a major change of direction, our working hypothesis is that the basic race model architecture is correct even if the race model test seems to suggest otherwise. Based on this approach, we argue that understanding the variability of responses is the key to understand the RSE. Finally, we highlight the critical role of model testability to advance research on multisensory decisions. Despite being largely rejected, it should be recognized that race models, as part of a broader class of parallel decision models, demonstrate, in fact, a convincing explanatory power in a range of experimental paradigms. To improve research consistency in the future, we conclude with a short checklist for RSE studies.

Qian (Janice) Wang and Charles Spence

We explored the putative existence of crossmodal correspondences between sound attributes and beverage temperature. An online pre-study was conducted first, in order to determine whether people would associate the auditory parameters of pitch and tempo with different imagined beverage temperatures. The same melody was manipulated to create a matrix of 25 variants with five different levels of both pitch and tempo. The participants were instructed to imagine consuming hot, room-temperature, or cold water, then to choose the melody that best matched the imagined drinking experience. The results revealed that imagining drinking cold water was associated with a significantly higher pitch than drinking both room-temperature and hot water, and with significantly faster tempo than room-temperature water. Next, the online study was replicated with participants in the lab tasting samples of hot, room-temperature, and cold water while choosing a melody that best matched the actual tasting experience. The results confirmed that, compared to room-temperature and hot water, the experience of cold water was associated with both significantly higher pitch and fast tempo. Possible mechanisms and potential applications of these results are discussed.

Daniel Poole, Ellen Poliakoff, Emma Gowen, Samuel Couth, Rebecca A. Champion and Paul A. Warren

A number of studies have shown that multisensory performance is well predicted by a statistically optimal maximum likelihood estimation (MLE) model. Under this model unisensory estimates are combined additively and weighted according to relative reliability. Recent theories have proposed that atypical sensation and perception commonly reported in autism spectrum condition (ASC) may result from differences in the use of reliability information. Furthermore, experimental studies have indicated that multisensory processing is less effective in those with the condition in comparison to neurotypical (NT) controls. In the present study, adults with ASC (n=13) and a matched NT group (n=13) completed a visual–haptic size judgement task (cf. Gori et al., 2008) in which participants compared the height of wooden blocks using either vision or haptics, and in a dual modality condition in which visual–haptic stimuli were presented in size conflict. Participants with ASC tended to produce more reliable estimates than the NT group. However, dual modality performance was not well predicted by the MLE model for either group. Performance was subsequently compared to alternative models in which the participant either switched between modalities trial to trial (rather than integrating) and a model of non-optimal integration. Performance of both groups was statistically comparable to the cue-switching model. These findings suggest that adults with ASC adopted a similar strategy to NTs when processing conflicting visual–haptic information. Findings are discussed in relation to multisensory perception in ASC and methodological considerations associated with multisensory conflict paradigms.

Séamas Weech and Nikolaus F. Troje

Studies of the illusory sense of self-motion elicited by a moving visual surround (‘vection’) have revealed key insights about how sensory information is integrated. Vection usually occurs after a delay of several seconds following visual motion onset, whereas self-motion in the natural environment is perceived immediately. It has been suggested that this latency relates to the sensory mismatch between visual and vestibular signals at motion onset. Here, we tested three techniques with the potential to reduce sensory mismatch in order to shorten vection onset latency: noisy galvanic vestibular stimulation (GVS) and bone conducted vibration (BCV) at the mastoid processes, and body vibration applied to the lower back. In Experiment 1, we examined vection latency for wide field visual rotations about the roll axis and applied a burst of stimulation at the start of visual motion. Both GVS and BCV reduced vection latency by two seconds compared to the control condition, whereas body vibration had no effect on latency. In Experiment 2, the visual stimulus rotated about the pitch, roll, or yaw axis and we found a similar facilitation of vection by both BCV and GVS in each case. In a control experiment, we confirmed that air-conducted sound administered through headphones was not sufficient to reduce vection onset latency. Together the results suggest that noisy vestibular stimulation facilitates vection, likely due to an upweighting of visual information caused by a reduction in vestibular sensory reliability.

Antonino Vallesi, Elisa D’Agati, Clementina Grelloni, Augusto Pasini, Giovanni Mazzotta and Paolo Curatolo

ADHD is associated with various cognitive deficits, including general performance decrements and specific impairments, for instance in temporal processing. However, time preparation under uncertain conditions has been under-investigated in this population. We aimed at filling this gap. We administered a variable foreperiod paradigm to children with ADHD before and after a one-month treatment with modified-release methylphenidate. Age-matched ADHD children with no treatment and healthy children were also tested as control groups with the same time-schedule. Children with ADHD had general performance deficits (longer and more variable response times), which disappeared in the experimental group after pharmacological intervention. Moreover, ADHD children showed a marked dependency on sequential foreperiod effects (i.e., slower responses for longer preceding foreperiods), especially at short current foreperiods, which were not modulated by the pharmacological treatment. In conclusion, the present findings show that methylphenidate enhances general motor processes rather than more specific time preparation processes, some of which appear deviant in ADHD.

Rochelle Ackerley, Michael Borich, Calogero Maria Oddo and Silvio Ionta

The present review focuses on the flow and interaction of somatosensory-motor signals in the central and peripheral nervous system. Specifically, where incoming sensory signals from the periphery are processed and interpreted to initiate behaviors, and how ongoing behaviors produce sensory consequences encoded and used to fine-tune subsequent actions. We describe the structure–function relations of this loop, how these relations can be modeled and aspects of somatosensory-motor rehabilitation. The work reviewed here shows that it is imperative to understand the fundamental mechanisms of the somatosensory-motor system to restore accurate motor abilities and appropriate somatosensory feedback. Knowledge of the salient neural mechanisms of sensory-motor integration has begun to generate innovative approaches to improve rehabilitation training following neurological impairments such as stroke. The present work supports the integration of basic science principles of sensory-motor integration into rehabilitation procedures to create new solutions for sensory-motor disorders.

Tsuyoshi Kuroda, Simon Grondin, Makoto Miyazaki, Katsuya Ogata and Shozo Tobimatsu

The kappa effect is a spatiotemporal illusion where duration is overestimated with the increase of space. This effect is typically demonstrated with three successive stimuli marking two neighboring empty time intervals, and the classical imputed velocity model, in principle, does not help to predict any spatial effects when only two stimuli, marking single intervals, are presented on each trial. We thus conducted three experiments, examining requirements for the occurrence of the kappa effect with only two visual stimuli. An interstimulus interval between the two stimuli was 217 (short) or 283 ms (long), and participants categorized the presented interval as ‘short’ or ‘long’. The key finding is that participants tended to respond ‘short’ more frequently than ‘long’ when both stimuli were delivered from the same location, whereas the relative frequency of ‘long’ responses was increased when the two stimuli were delivered from different locations in most directions (i.e., horizontally, vertically, diagonally; Experiment 1). This kappa effect clearly occurred when each stimulus was located 8° apart from the fovea in visual angle, but it was reduced when each stimulus was further deviated from the fovea, regardless of whether the two stimuli were presented in the vertical or the horizontal direction (Experiments 2 and 3). Moreover, increasing the spatial distance between the two stimuli from 15 to 30 cm magnified the effect only in a limited condition (Experiment 3). Implications of these results were discussed in terms of the Bayesian model predicting the effects of spatial acuity.

Christoph Redies, Anselm Brachmann and Gregor Uwe Hayn-Leichsenring

During the creation of graphic artworks, we studied the evolution of higher-order statistical image properties (complexity, self-similarity, anisotropy of oriented luminance gradients, the slope of log–log plots of radially averaged Fourier power, and the fractal dimension). First, we analyzed two series of lithographs by Pablo Picasso, which represent transformations of highly aesthetic artworks. Second, one of the authors generated a dataset of 20 grayscale drawings using the computer as a drawing tool. The dataset comprised also the unfinished state images that were saved throughout the production process. The final states of the drawings were compared to versions of the same drawings, in which the constituent pictorial elements were shuffled, thereby diminishing the overall compositional intent of the artist. Results show that self-similarity was a property closely associated with artistic merit in the different types of images analyzed. In a psychological experiment, 20 non-expert participants evaluated the original abstract drawings as more harmonious and ordered but less interesting than the shuffled versions. Our study demonstrates that statistical image properties can be studied during the creation of artworks, if artistic and analytical processes are closely coordinated in a computer-based approach, which offers the possibility to produce appropriate control stimuli.

James E. Cutting

I investigated the number and locations of characters as they appear on the screen in 48 popular movies released from 1935 to 2010. Sampling an average of one of every 500 frames (∼20 s of film) I amassed data from almost 14 000 movie images. The number and placement of the characters in each image were digitally recorded and compared across years and across aspect ratios (the ratio of the width to the height of the image). Results show a roughly linear decrease in the number of characters on the screen across years. Moreover, the number of characters influences shot scale, shot duration, and mediates their direct effect on one another. The location of characters on the screen was measured by the bridge of the nose between the eyes. By this measure I found that framing varies widely across aspect ratios, but when each image is conformed to the same shape, the overlap of the locations of characters is remarkably constant across years and aspect ratios for images with one, two, and three characters. Together, these results exemplify both constancy and change in the evolution of popular movies.