Intra-individual variability (IIV) refers to within-person variability in behavioral task responses. Increased IIV may indicate inefficient cognitive processing and decreased central nervous system integrity. The impact of aging on the relationship between IIV and emotional response inhibition is unknown given age-related changes in emotion processing. The present study examined if age and/or task instruction modulated the relationship between IIV and motor response inhibition to emotional stimuli. We used an emotional stop signal task that displayed human faces with happy, fear, or neutral expressions in ‘Stop’ trials. Older (age = 60-86 yrs) and younger (age = 17-27 yrs) adults (N = 237) completed one of three versions of the task: emotion was task-irrelevant for the stop-signal for the first two versions, and task-relevant in the third version. Stop signal reaction times (SSRT) were used as a measure of emotional response inhibition. IIV was measured using the standard deviation of the response time for accurate ‘Go’ trials We observed a significant positive relationship between response consistency and inhibition only when emotion was task-relevant; when task instructions required overt focus on emotion, people with more consistent responses (i.e., lower IIV) had more efficient response inhibition (i.e., lower SSRT) only for fear expressions. Overt focus on facial expression may amplify attention-eliciting characteristics of negative stimuli. Although younger adults had significantly greater IIV than older adults, age did not pose an interactive effect. The age-related differences in consistency may be explained by an increased propensity of younger adults to engage in mind wandering.

Dr. Jill Waring was influential to Shalmali throughout the project. Dr. Waring mentored Shalmali on the process of conducting a literature review, data analysis, and presenting the research findings as well.

Shalmali would also like to thank the members of the Cognitive and Affective Neuroscience of Aging Lab for help with data collection.