Eye Tracking Attentional Control in Aging Adults

The ability to focus attention and ignore distractions is crucial for everyday functioning. However, it is widely observed that older adults are more susceptible to distraction than younger adults. This case study examines the research paper, “Aging impairs reactive attentional control but not proactive distractor inhibition,” by Kim et al. (2024), which investigates the specific mechanisms of attentional control affected by aging. The study utilizes eye-tracking technology to provide a detailed understanding of how older adults process visual information and inhibit irrelevant stimuli.

The central research question they address is the extent to which aging modulates both reactive attentional control and proactive distractor inhibition. The authors sought to reconcile mixed findings in the literature regarding age-related deficits in inhibition by differentiating between these two forms of attentional control. They hypothesized that the impact of aging on attentional control would depend on whether the task required proactive suppression of known distractors or reactive disengagement from unexpected salient stimuli.

Eye Tracking Visual Search with Aging Adults

The study involved two experiments, both utilizing oculomotor visual search paradigms with young and older adults. In each experiment, eye movements were recorded with a desktop mounted SR Research EyeLink 1000 Plus.

Experiment 1: Proactive Distractor Suppression

In Experiment 1, participants performed a feature-search task where they had prior knowledge of the distractor’s feature (e.g., a specific color). The key findings were:

• Preserved Proactive Distractor Suppression: Both young and older adults demonstrated a positive oculomotor suppression effect, indicating that older adults could inhibit attention allocation toward salient but task-irrelevant distractors as effectively as young adults. This suggests that proactive distractor suppression mechanisms are preserved with age.
• Impaired Goal-Directed Attentional Control: Despite preserved distractor suppression, older adults made significantly fewer first saccades to the target compared to young adults, even in distractor-absent trials. This indicates a general decline in goal-directed attentional control in older adults.
• Impaired Disengagement (Dwell Time): Older adults exhibited longer dwell times on incorrect initial saccades, suggesting deficiencies in reactively disengaging from non-target stimuli.
• Age-Related Delays in Saccadic Reaction Times (sRTs): Older adults showed extended sRTs when saccades were directed towards the target, pointing to age-related delays in processing top-down information.

Experiment 2: Reactive Distractor Disengagement

Experiment 2 employed an “additional singleton task” requiring participants to engage in singleton-search mode, where they could not proactively suppress the distractor. The findings revealed:

• Impaired Reactive Attentional Control: Older adults demonstrated significantly more oculomotor capture by salient, task-irrelevant distractors compared to young adults. This indicates that reactive disengagement from unexpected distractions is impaired with age.
• Exacerbated Distractor Presence Deficit: The presence of a distractor significantly delayed fixation times more in older adults than in young adults.
• Increased Dwell Times and sRTs: Older adults had longer dwell times on incorrect fixations and significantly longer sRTs when saccades were directed towards the distractor, further supporting difficulties in reactive disengagement.
• Deficiencies in Goal-Directed Attentional Control: Similar to Experiment 1, older adults showed reduced first saccades to the target, even in distractor-absent trials.

Aging Adults Struggle with Unexpected Salient Stimuli

By tracking the timing and direction of eye movements (e.g., first saccade destination, fixation times, dwell times, and saccadic reaction times), Kim et al. were able to:

• Differentiate Attentional Mechanisms: Eye-tracking allowed for the distinction between proactive (pre-stimulus) and reactive (post-stimulus) attentional control, which was fundamental to the study’s conclusions.
• Measure Early Stages of Attention: First saccades provided insight into the initial competition resolution between goal-directed and stimulus-driven attention.
• Quantify Disengagement Difficulties: Dwell times on incorrect fixations directly measured the time taken to disengage from irrelevant stimuli, offering a clear index of reactive control.
• Uncover Processing Delays: Saccadic reaction times revealed the speed of initiating eye movements and processing competing neural signals.

The precise temporal resolution of eye-tracking data allowed the researchers to demonstrate that while older adults can proactively inhibit distractions, they struggle more with reactively disengaging from unexpected salient stimuli.

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