Spatial attention and representation of time intervals in childhood

Abstract

Spatial attention and spatial representation of time are strictly linked in the human brain. In young adults, a leftward shift of spatial attention by prismatic adaptation (PA), is associated with an underestimation whereas a rightward shift is associated with an overestimation of time both for visual and auditory stimuli. These results suggest a supra-modal representation of time left-to-right oriented that is modulated by a bilateral attentional shift. However, there is evidence of unilateral, instead of bilateral, effects of PA on time in elderly adults suggesting an influence of age on these effects. Here we studied the effects of spatial attention on time representation focusing on childhood. Fifty-four children aged from 5 to 11 years-old performed a temporal bisection task with visual and auditory stimuli before and after PA inducing a leftward or a rightward attentional shift. Results showed that children underestimated time after a leftward attentional shift either for visual or auditory stimuli, whereas a rightward attentional shift had null effect on time. Our results are discussed as a partial maturation of the link between spatial attention and time representation in childhood, due to immaturity of interhemispheric interactions or of executive functions necessary for the attentional complete influence on time representation.

Improvement of phonemic fluency following leftward prism adaptation

“…On the other hand, since sensorimotor aftereffect and cognitive effect act at different levels, they are not consistently reported together, as suggested by other experiments exploring the effects of leftward PA in both healthy subjects and neurological patients. Schintu et al 19 reported modulation of left hemisphere dopaminergic activity in healthy subjects following leftward PA, without differences in the amount of sensorimotor effects induced by leftward vs. rightward PA. Frassinetti et al 13 first documented underestimation of time perception following leftward PA, a finding consistently replicated in other studies and correlated with the amount of sensorimotor effects 8 , 10 , 11 , 14 , 20 . In neurological patients, leftward PA has been shown to reshape visuospatial representation in left brain damaged patients with right neglect 67 – 69 .…”

“…In the exposure condition, 90 trials in visible pointing were administered; subjects wore prismatic lenses that induced a 20° shift of the visual field to the right or to the left. In the post-exposure condition, 30 trials in invisible pointing were administered immediately after removal of the prisms 20 .…”

“…To verify whether subjects adapted to prism deviation, showing an error reduction following rightward or leftward deviation, we compared their displacement measure in the pre-exposure (visible pointing) condition with that of the first three (early- exposure condition) and the last three trials (late-exposure condition) of the exposure condition (more details on this procedure can be found in 20 ). A difference between a pre-exposure condition and the early-exposure condition is expected due to the rightward or leftward displacement induced by prism exposure.…”

“…If, after prism exposure, subjects point to the direction opposite the displacement induced by the prism, a difference is expected between the pre- and the post-exposure conditions (aftereffect). The dependent measure was the mean displacement (expressed in degrees of visual angle) of the subjects' invisible pointing responses in the pre-exposure condition and the post-exposure condition 20 . An ANOVA was conducted with Condition (L-PA; R-PA) as between-subjects and Session (pre-exposure, post-exposure) as within-subjects variable.…”

“…PA cognitive effects have also been reported in visual search 6 , endogenous and/or exogenous orienting of attention 7 , spatial/temporal representation 8 – 14 , visually guided actions 15 , auditory representation 16 , chronic pain 17 , constructional disorders 18 and reward-based learning 19 . Lateralized effects of PA have been reported to be dependent on the age, being more evident in young adults 20 .…”