Multisensory interactions follow the hands across the midline: Evidence from a non-spatial visual–tactile congruency task
Authors: Gemma A Calvert
Daniel Sanabria
Charles Spence
Nicholas P Holmes
Journal: Brain Research (2006)
Discipline: NEUROSCIENCE & BEHAVIOR
Keywords: hands crossed; spatial compatibility; tactile discrimination; visual distractors; crossmodal congruency effect
Affiliations: Department of Experimental Psychology, South Parks Road, Oxford OX1 3UD, UK. 

Abstract:  Crossing the hands over, whether across the body midline or with respect to each other, leads to measurable changes in spatial compatibility, spatial attention, and frequently to a general decrement in discrimination performance for tactile stimuli. The majority of multisensory crossed hands effects, however, have been demonstrated with explicit or implicit spatial discrimination tasks, raising the question of whether non-spatial discrimination tasks also show spatial effects when the hands are crossed. We designed a novel, non-spatial tactile discrimination task to address this issue. Participants made speeded discriminations of single- versus double-pulse vibrotactile targets, while trying to ignore simultaneous visual distractor stimuli, in both hands uncrossed and hands crossed postures. Tactile discrimination performance was significantly affected by the visual distractors (demonstrating a significant crossmodal congruency effect) and was affected most by visual distractors in the same external location as the tactile target (i.e., spatial modulation), regardless of the posture (uncrossed or crossed) of the hands (i.e., spatial 'remapping' of visual-tactile interactions). Finally, crossing the hands led to a general performance decrement with visual distractors, but not in a control task with unimodal visual or tactile judgements. These results demonstrate, for the first time, significant spatial and postural modulations of crossmodal congruency effects in a non-spatial discrimination task. 

Retracted: No

PubPeer comments:
 This paper was criticised as part of a self-reflection posted on Twitter on 2nd-3rd April, 2021 (twitter TheHandLab status 1377760796130869248) Criticism: In the lab we always looked at reaction times (RT) errors (%) their combination inverse efficiency , IE=RT p(correct). Papers relied either on RT, % or IE. This paper used % because the p-value for IE was 0.06 I don t feel we were selective in reporting these data - all the p-values are clearly in the main text. Overall, the problem here is that, in most of our papers we would use IE scores so that we could make some correction for any speed-accuracy trade-offs that might exist in the data or experiment. In this experiment, all the effects we looked at (see also the later paper by Holmes et al. 2007, in Cortex, https: doi.org 10.1016 S0010-9452(08)70471-4) seemed to occur in the error data only. This would be the case, for example, in the kinds of discrete perceptual illusions that we thought we were studying (i.e., with a visual-tactile illusion you may be certain, but wrong, and may respond quickly, so errors and RT will not be traded-off against each other). However, combining RT and errors to make the IE score usually resulted in an increase in variability, smaller effect sizes, and lower power. The study was underpowered to use RT or IE scores. Conclusion: replications of this experiment should probably use the IE scores to estimate sample size, or just focus on errors and ignore RT completely. ,