Word Generation Affects Continuous Hand Movements

ABSTRACT

Understanding interactions between cognitive and motor performance is an important theoretical and practical aim of motor neuroscience. Toward this aim, we invited university students to move one hand back and forth at a self-paced rate either in silence or while overtly generating words from semantic categories. The same participants also generated words without movement. Word generation affected manual performance but manual performance did not affect word generation. Only the timing, but not the spatial features, of the hand movements were influenced by word generation. The simplicity of our procedure argues for its future use, both for theoretical and practical purposes.

Keywords:

• cognition
• dual-task performance
• hand movements
• measurement of movements

ACKNOWLEDGMENTS

This article is based on the senior honors thesis of Lisai Zhang, conducted under the supervision of David A. Rosenbaum. Ms. Zhang and Dr. Rosenbaum became familiar with Dr. Wininger after the data were collected. They invited him to join in to apply his special data analysis methods and related expertise to the study. Ms. Zhang is now a medical school student.

Notes

1. We did not compute CVs for the values described in the final two rows of Table 2, the nondimensionalized jerk and the log temporally normalized jerk, because variation in jerk and jerk-related measures is seldom reported and we had no hypotheses about it.

2. When we embarked on this project, we considered the possibility of pairing cyclic hand movements with backwards counting. A representative backwards-counting task is subtracting by threes starting from some number such as 97. This method has been used to shed light on the limited capacity of short-term memory (Peterson & Peterson, 1959). We decided not to use this method, however, because we thought the word generation task was potentially richer. Moreover, we did not want to bump up against a canonical stopping point (reaching zero in subtraction).