Time-of-day and attentional-order influences on dichotic processing of digits in learning disabled and normal...

A heterogeneous group of 26 learning disabled (LD) and 30 normal achieving (NA) children, responded to a dichotic listening task using digits in morning and afternoon settings. Attentional order (i.e., right ear first versus left ear first) interacted with (1) Time-of-Day and (2) Group and Ear Attended. The first interaction revealed, as predicted, higher morning performance for subjects directed to attend right first. Subjects directed left first showed higher afternoon performance. These results are consistent with enhanced left hemisphere involvement after left hemisphere priming in the morning, and after right hemisphere priming in the afternoon. The second interaction indicated the LD had more difficulty than controls switching attention to the right ear when instructed to attend left first. The LD may activate the right hemisphere (via left hemispace attending) and have difficulty with subsequent right hemisphere inhibition, or left hemisphere activation, when shifting to right ear attending. Nonparametric tests revealed a greater incidence of lateralized responders in the morning for normal achievers attending left first. Findings are seen to augment previous research.