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.