Quantifying the effort individuals with aphasia invest in working memory tasks through heart rate variability

The objective of this study was to quantify cognitive effort that individuals with aphasia and neurologically intact participants dedicate to verbal compared with spatial working memory tasks by using a physiological measure of effort: heart rate variability (HRV).

Participants included 8 individuals with aphasia and 19 neurologically intact adults. Participants completed 3 verbal and 3 spatial working memory tasks that varied in difficulty. Performance accuracy and effort allocated to tasks was recorded. Effort was quantified as the change in the 0.07-0.14 Hz band of HRV from baseline to task conditions.

Results indicated that individuals with aphasia and control participants allocated effort to verbal and spatial working memory tasks. Unlike the control participants, participants with aphasia did not differentially invest effort based on task difficulty. Neither group allocated effort differentially based on task type.

Results of the physiological data provide preliminary support for accounts indicating that individuals with aphasia do not properly allocate effort to cognitive-linguistic tasks. Analysis of the Group × Difficulty interaction indicated that the aphasia group did not allocate extra effort when it was required. The lack of a difference in HRV for spatial and verbal tasks suggests that this difference is not specific to verbal stimuli.