Enhanced Simon effect in older test subjects?
This student project was executed in 2011 to investigate age as well as practice dependencies (Lubbe, 2002) of the Simon-effect. The so-called Simon-task is a measure of interference-resolution The latter refers to cognitive control processes to filter out unrelated information while keeping focus on task-related information. It demonstrates that spatial information influences reaction time and error rate when performing a choice-reaction-task, even if the stimulus location is irrelevant to the task. Practically, this means people respond faster and more accurately if there is a match between stimulus and response. For example, if a left (rather than a right) keypress is the required response to a blue stimulus, reaction time will be quicker if this stimulus is presented on the left-hand side than if it is presented on the right (and vice versa).
As a team of five and in the context of a semester project (movement science) we investigated if the Simon-effect gets stronger in older test subjects. By this time, the scientific landscape on this specific topic was poor especially in the context of visual cues. Therefore we wanted to test how age affects visual-spatial attention as well as inhibitory control of attention. The biggest challenge in this context was to distinguish the Simon-effect itself from the desired age effect. We planned for a group comparison and collaborated with the central college sport institution of the Technical University Munich (TUM) to recruit for the samples. Based on our course literature we expected a) stronger effects with raising age, b) younger participants to react around 100ms quicker than older ones independent of stimulus location and c) that higher error rates as well as longer reaction times would potentially occur when there was no correlation between irrelevant information and the response reaction.
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STUDY DESIGN:
group 1: Pensioners (n=13, 11 men, 2 women), average age = 69.2 years (+/- 7.3 years), “Herzsport” (english: cardio-vascular-exercise group for people above 60 years)
group 2: Students (n=13, 11 men, 2 women), average age of 23.8 years (+/- 1.1 years), sport student’
independent variable: age
Dependent variable 1: reaction time (corrected for mistakes)
Dependent variable 2: number of errors
Dependent variable 3: reaction time difference 1st half vs. 2nd half
analysis: ANOVA, SPSS
software: Neurobs.com test battery
RESULTS - HYPOTHESIS REJECTED
In both groups we found significant longer reaction times for incongruity (= Simon-effect) as well as practice effects (effect in second half bigger than in first half). Furthermore the pensioners were significantly slower than the students (= age effect). However, we did not see an enhancement of the Simon effect per se for the pensioners (no interaction between group and condition). This caused us to reject our hypothesis of an age-related enhancement of the Simon-effect.
Among other reasons, an interesting explanation for this result could be the extensive amount of coordination exercises executed within the “Herzsport”-group. When interviewing our participants subsequent to the study (as a part of the study exercise) we found out, that our pensioners regularly performed coordination tasks to improve reaction skills within their exercise course. Their instructors focus on these skills to help them prevent serious age-related injuries (e.g. femoral leg fractures) that often occur with higher age due to stumbling combined with poor reaction times. At the same time our sport students put more focus on endurance and exercise within their studies and leisure time activities. Overall the results were surprising and very promising for further activities. We recommended to investigate a replication of this study with a bigger sample size and to consider a more distinctive group of pensioners with regards to activity (“very active”, “normal”, “inactive”).
LITERATURE
Simon, R. J. & Rudell, P. A. (1967): The effect of an irrelevant cue on information processing. In: Journal of applied Psychology, Nr. 51 (3), S. 300-304.
Van der Lubbe, H. J. R. & Verleger, R. (2002): Aging and the Simon task. In: Psychophysiology, Nr. 39, S.100-110.
Germain, S. & Collette, F. (2008): Dissociation of perceptual and motor inhibitory processes in young and elderly participants using the Simon task. In: Journal of the International Neuropsychological Society,14, S.1014- 1021.