Reversal of subjective temporal order due to arm crossing

Abstract

How does the brain order successive events? Here we studied whether temporal order of two stimuli delivered in rapid succession, one to each hand, is determined before or after the stimuli are localized in space. When their arms were crossed, subjects could accurately report the temporal order, even when the interval between stimuli was as short as 70 ms. In most trials, subjects could also judge temporal order when their arms were crossed, but only if given adequate time (>1 s). At moderately short intervals (<300 ms), crossing the arms caused misreporting (that is, inverting) of the temporal order. Thus, at these intervals, the determining factor of temporal order was the spatial location of the hands. We suggest that it is not until the spatial locations of the hands are taken into account that the cutaneous signals from the respective hands are ordered in time.

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

“…Additionally, participants responded more rapidly when their hands were held in an uncrossed posture (787 ± 24 ms) than when their hands were crossed (804 ± 24 ms), as has been reported in other speeded tasks [16,34]. This difference of 17 ± 9 ms across participants just failed to reach statistical significance (p = .058).…”

A three-dimensional spatial characterization of the crossed-hands deficit

“…In this posture, a touch on the right hand (in skin-based coordinates), is located in left space, creating an incongruence between reference frames in the right-left dimension (Shore et al, 2002;Yamamoto & Kitazawa, 2001; for a review see Heed, Buchholz, Engel, & Röder, 2015). A well-known consequence of this conflicting information is the impairment in the ability to report the order of two stimuli, one applied to each hand, when hands are crossed (Heed & Azañón, 2014;Shore et al, 2002;Yamamoto & Kitazawa, 2001).…”

“…In this posture, a touch on the right hand (in skin-based coordinates), is located in left space, creating an incongruence between reference frames in the right-left dimension (Shore et al, 2002;Yamamoto & Kitazawa, 2001; for a review see Heed, Buchholz, Engel, & Röder, 2015). A well-known consequence of this conflicting information is the impairment in the ability to report the order of two stimuli, one applied to each hand, when hands are crossed (Heed & Azañón, 2014;Shore et al, 2002;Yamamoto & Kitazawa, 2001). In such instances, the order of two stimuli might be correctly computed, but it is inaccurately reported because of the incorrect localization of the stimuli in space (Badde, Heed, & Röder, 2016;Overvliet, Azañón, & Soto-Faraco, 2011;Roberts & Humphreys, 2008).…”

“…In such instances, the order of two stimuli might be correctly computed, but it is inaccurately reported because of the incorrect localization of the stimuli in space (Badde, Heed, & Röder, 2016;Overvliet, Azañón, & Soto-Faraco, 2011;Roberts & Humphreys, 2008). This result has been interpreted as evidence that posture is taken into account automatically, even if it impairs task performance (Azañón, Camacho, & Soto-Faraco, 2010;Kitazawa, 2002;Yamamoto & Kitazawa, 2001). In the remapping literature, this idea has been extrapolated indirectly to all postures, to the extent that it is generally assumed that tactile remapping (or the encoding of touch in external space) is a general step in tactile processing (Azañón & Soto-Faraco, 2008;Kitazawa, 2002;Overvliet et al, 2011;Röder et al, 2004).…”

“…The hand crossing effect has been suggested to result, amongst other models, from either an impairment of coordinate transformation (Yamamoto & Kitazawa, 2001) or a conflict in the integration of disparate spatial information (Badde et al, 2016;Badde, Röder, & Heed, 2015;Heed et al, 2015). Regardless of the interpretation of the origin of the effect, all these studies assume that the deficit indexes an automatic triggering of spatial transformations during tactile processing.…”