Multisensory interactions follow the hands across the midline: Evidence from a non-spatial visual–tactile congruency task

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.

Visual Phosphene Perception Modulated by Subthreshold Crossmodal Sensory Stimulation

“…In our study, the crossmodal enhancement effect was still present when the hands were in the crossed position. Crossmodal enhancement effects have been shown to arise even if the tactile cues are task irrelevant and do not predict the location of the visual targets (i.e., follow the hand position), suggesting an exogenous (stimulus-driven) attentional mechanism (Holmes et al, 2006). In our experiment, subthreshold stimuli reveal a crossmodal effect that follows the hand.…”

Crossmodal representation of a functional robotic hand arises after extensive training in healthy participants

“…Although the majority of CCE studies have documented a significant same-opposite difference in the incongruency effect, a lack of spatial modulations by the side of distracter has been previously reported in a version of the crossmodal congruency paradigm which required an identity discrimination task (Holmes, Sanabria, Spence, & Calvert, 2006) and in a version of the task which used visual targets and tactile distracters (Walton & Spence, 2004).…”

Adapting the Crossmodal Congruency Task for Measuring the Limits of Visual–Tactile Interactions Within and Between Groups

“…Experiment 2 was designed to replicate the spatial modulation of the CE (e.g., Holmes et al, 2006;Pavani et al, 2000). Distractors were presented to the participant's stimulated hand and at an equivalent position in the contralat eral hemispace.…”

“…Finally, we used a simplified unimanual, single versus double task. The tactile target was presented unimanually to the dominant hand (Spence et al, 2001), rather than bimanually as in traditional versions of the task, and participants made a non-spatial (single versus double) tactile judgement (Holmes et al, 2006(Holmes et al, , 2008 rather than an elevation judgement, which required only a single light emitting diode (LED). These simplifications were designed to reduce task demands for participant groups (such as older adults) and, as will be described below, to enable spatial modulation to be measured more effectively.…”