Can irrelevant but salient visual cues compensate for the age-related decline in cognitive conflict resolution?-An ERP study

Abstract

We studied a Posner-type gaze-cued version of a Simon task to characterize age-related changes in visuospatial attention and inhibitory control. Earlier results had indicated that the direction of gaze is a strong social cue that speeds response times; so we wondered whether, as a task-irrelevant stimulus, it could compensate for age-related impairment of inhibitory processes in the elderly. Our results assessed the Simon effect by: reaction time, error rate, the P3 component and the lateralized readiness potential (LRP). We found that the Simon effect was larger in the older group confirming an increased sensitivity to interference and also suggesting a decreased inhibitory control in older adults. LRP results showed that aging and stimulus-response incongruency delayed the selection of the responses-indexed by longer s-LRP latency data-, and also decreased the efficiency of motor inhibition in the Simon task-the s-LRP amplitude of both wrong- and correct-side activation was larger in older adults, and the latency difference of these two components was longer in this age-group. Also a larger N2pc amplitude in the congruent, compared to incongruent gaze condition, showed an increased visuospatial attention when the gaze-cueing drew attention to the target stimulus. This gaze-cueing could not be ignored and hence it modified task processing in the older age group, which was evident in the incongruent Simon condition where the congruent gaze increased older adults' reaction time and their error rate; but there was no difference observed in the congruent Simon condition. Since the anticipated facilitation of reaction times did not occur, we suggest that general slowing and decreased inhibitory functions in the elderly caused the social cue not to be a supporting stimulus but rather to be a further burden on their cognitive processing.

Fig 1. Different combinations of simon and putative gaze effects.

(A) Different levels of correct response facilitation (+: facilitation,—: inhibition) for different combinations (trials) of Simon and Gaze conditions (CS: congruent Simon, ICS: incongruent Simon, CG: congruent Gaze, ICG: incongruent Gaze). (B) Stimuli of the four conditions (example): CS-CG on the top left, CS-ICG on the top right, ICS-CG on the bottom left, ICS-ICG on the bottom right.

Fig 2. Illustration of the sequence and timing of stimuli in the face cued trials (top row) and the patch cued trials (bottom row).

ITI is for intertrial interval.

Fig 3. Error rates (%) in the congruent and incongruent simon tasks when the gaze was congruent (CG) and incongruent (ICG) in the young and older age groups.

(Vertical bars denote 95% confidence intervals).

Fig 4. Reaction time data (mean and standard deviation) of young and older adults for face and patch cues in congruent gaze-congruent simon (CG-CS), incongruent gaze-congruent simon (ICG-CS), congruent gaze-incongruent simon (CG-ICS), and incongruent gaze-incongruent simon (ICG-ICS) conditions.

Fig 5. Target-locked N2pc component at the P7-P8 electrode difference (contra-minus-ipsilateral to the presentation side of the target stimulus) in young (top row) and older (bottom row) adults and in face (left side) and patch (right side) trials.

The x-axis represents the epoch from -450 ms to 800 ms around the time-point of target presentation. CS-CG (congruent Simon, congruent gaze) waveforms are displayed in red, ICS (incongruent Simon)-CG waveforms in black, CS-ICG (incongruent gaze) waveforms in blue, and ICS-ICG waveforms in green. Grey rectangles represent the search window for maximal N2pc amplitude.

Fig 6. Target-locked P3b component at the Pz electrode site in young (top row) and older (bottom row) adults and in face (left side) and patch (right side) trials.

The x-axis represents the epoch from -450 ms to 800 ms around the time-point of target presentation. CS-CG (congruent Simon, congruent gaze) waveforms are displayed in red, ICS (incongruent Simon)-CG waveforms in black, CS-ICG (incongruent gaze) waveforms in blue, and ICS-ICG waveforms in green. Grey rectangles represent the search window for maximal P3 amplitude.

Fig 7. Stimulus-locked LRP component at the C3-C4 electrode difference (contra-minus-ipsilateral to the responding hand) in young (top panel) and older (bottom panel) adults and in face (left side) and patch (right side) trials.

The x-axis represents the epoch from -450 ms to 800 ms around the time-point of target presentation. CS-CG (congruent Simon, congruent gaze) waveforms are displayed in red, ICS (incongruent Simon)-CG waveforms in black, CS-ICG (incongruent gaze) waveforms in blue, and ICS-ICG waveforms in green. The arrows show the positive dips of wrong side activation, and the latency ranges are indicated in which the t-test showed significant differences from the baseline in the 200–350 ms window. Grey rectangles represent the search window for maximal s-LRP amplitude in every subject.

Fig 8. Response-locked LRP component at the C3-C4 electrode difference (contra-minus-ipsilateral to the responding hand) in young (top panel) and older (bottom panel) adults and in face (left side) and patch (right side) trials.

The x-axis represents the epoch from -400 ms to 200 ms around the time-point of the response. CS-CG (congruent Simon, congruent gaze) waveforms are displayed in red, ICS (incongruent Simon)-CG waveforms in black, CS-ICG (incongruent gaze) waveforms in blue, and ICS-ICG waveforms in green. Grey rectangles represent the search window for maximal r-LRP amplitude in every subject.