A conflict between an egocentric and an external reference frame can be highlighted by examining the marked deficit observed with tactile temporal order judgments (TOJ) when the hands are crossed. The anecdotally-reported large individual differences in the magnitude of this crossed-hands deficit were explored here by testing a large group of participants (48; 24 female). Given that females have been shown to be more visually dependent than males in the potentially related rod-and-frame test (RFT), we hypothesized that females would show a larger influence of the external reference frame (i.e., a larger crossed-hands deficit). As predicted, female participants produced larger tactile TOJ deficits compared to our male participants. We also administered the RFT in these participants with hands crossed and uncrossed. Crossing the hands increased the effect of the frame in the RFT, more so for females than males, further highlighting the potential difference in the way that each sex accommodates reference frame conflicts. Finally, examining the relation between the two tasks revealed a significant correlation, with larger frame effects associated with larger crossed-hands TOJ deficits, but this only held for males. We speculate that sex-specific differences in multisensory processing and spatial ability may explain why females are less able to disambiguate a crossed-hands posture than are males.

Performance on tactile temporal order judgments (TOJs) is impaired when the hands are crossed over the midline. The cause of this effect appears to be tied to the use of an external reference frame, most likely based on visual information. We measured the effect of degrading the external reference frame on the crossed-hand deficit through restriction of visual information across three experiments. Experiments 1 and 2 examined three visual conditions (eyes open-lights on, eyes open-lights off, and eyes closed-lights off) while manipulating response demands; no effect of visual condition was seen. In Experiment 3, response demands were altered to be maximally connected to the internal reference frame and only two visual conditions were tested: eyes open-lights on, eyes closed-lights off. Blindfolded participants had a reduced crossed-hands deficit. Results are discussed in terms of the time needed to recode stimuli from an internal to an external reference frame and the role of conflict between these two reference frames in causing this effect.

Many researchers have taken the Colavita effect to represent a paradigm case of visual dominance. Broadly defined, the effect occurs when people fail to respond to an auditory target if they also have to respond to a visual target presented at the same time. Previous studies have revealed the remarkable resilience of this effect to various manipulations. In fact, a reversal of the Colavita visual dominance effect (i.e., auditory dominance) has never been reported. Here, we present a series of experiments designed to investigate whether it is possible to reverse the Colavita effect when the target stimuli consist of repetitions embedded in simultaneously presented auditory and visual streams of stimuli. In line with previous findings, the Colavita effect was still observed for an immediate repetition task, but when an n-1 repetition detection task was used, a reversal of visual dominance was demonstrated. These results suggest that masking from intervening stimuli between n-1 repetition targets was responsible for the elimination and reversal of the Colavita visual dominance effect. They further suggest that varying the presence of a mask (pattern, conceptual, or absent) in the repetition detection task gives rise to different patterns of sensory dominance (i.e., visual dominance, an elimination of the Colavita effect, or even auditory dominance).

No abstract

The rubber hand illusion (RHI) is a multisensory (visual, tactile, proprioceptive) illusion in which participants report body ownership over, mislocalize actual hand position to, and feel touches applied to, the rubber hand. For many years, researchers have used changes in perceived hand position, measured by inter-manual pointing, as a more objective measure of the illusion than verbal reports alone. Despite this reliance, there is little evidence to show that the illusion of hand ownership is directly related to perceived hand position. We developed an adaptive staircase procedure to measure perceived hand position, and tested whether the RHI affected perceived hand position. In two experiments we found a significant illusion of ownership, as well as significant changes in perceived hand position, but these two measures were uncorrelated. In a third experiment using more typical RHI procedures, we again replicated significant illusions of ownership and changes in hand position, but again the measures were uncorrelated. We conclude that viewing and feeling touches applied to a dummy hand results in clear illusions of ownership and changes in hand position, but via independent mechanisms.