Executive Function in Left-Handed Young Adults: Evidence From the Trail Making Test

Background: Left-handed individuals may experience performance disadvantages in right-hand-oriented environments; however, these circumstances could also foster adaptability, potentially leading to greater executive function. Switching ability, a component of executive function, reflects flexibility in adjusting to environmental changes. Prior research on left-handers' executive function has yielded inconsistent results. Additionally, many tests have not controlled for confounding factors, such as attention, sequencing, and motor processes. Purpose: Accordingly, the present study aimed to examine differences in executive function between left- and right-handed participants while controlling for significant confounding factors. Research Design: A cross-sectional comparative design was employed. Study Sample: The participants included 25 right-handed and 26 left-handed individuals. Data Collection and/or Analysis: The present study used the Delis-Kaplan Executive Function System (D-KEFS) Trail Making Test (TMT) to examine differences in executive function between left- and right-handed participants. Results: It was hypothesized that handedness would significantly influence performance, with left-handers demonstrating superior switching ability compared with right-handers. Results revealed significant differences in sequencing errors on TMT Condition 4, with right-handed participants making fewer errors than left-handed participants, whose higher error rates suggest disadvantaged switching abilities. Furthermore, left-handed participants were more likely to commit specific number and letter sequencing errors, which may have been influenced by the interaction of impulsivity with stimulus-response incompatibility, biomechanical inefficiency, and attentional or scanning bias. Conclusions: These findings suggest that left-handed participants may demonstrate relatively disadvantaged switching abilities under the tested conditions, potentially influenced by multiple interacting cognitive and motor factors.