Visuospatial working memory capacity predicts the organization of acquired explicit motor sequences

Abstract

Studies have suggested that cognitive processes such as working memory and temporal control contribute to motor sequence learning. These processes engage overlapping brain regions with sequence learning, but concrete evidence has been lacking. In this study, we determined whether limits in visuospatial working memory capacity and temporal control abilities affect the temporal organization of explicitly acquired motor sequences. Participants performed an explicit sequence learning task, a visuospatial working memory task, and a continuous tapping timing task. We found that visuospatial working memory capacity, but not the CV from the timing task, correlated with the rate of motor sequence learning and the chunking pattern observed in the learned sequence. These results show that individual differences in short-term visuospatial working memory capacity, but not temporal control, predict the temporal structure of explicitly acquired motor sequences.

FIG. 1.

Illustration of the chunking realignment procedure. A: 4 initial chunking points identified for 1 representative participant. B: plots realigned with respect to each chunk point in the sequence. C: 2 initial chunking points with different chunk lengths for another participant. D: plots realigned to each chunk point for the example in C.

FIG. 2.

A: the mean reaction time for each trial in steps 1 and 2. B: the mean accuracy for each block in steps 1 and 2.

FIG. 3.

A: the response time from the 3 blocks of step 4 of sequence training are depicted for 2 representative participants. B: the mean response time for each trial in steps 3 and 4. C: the mean accuracy for each block in steps 3 and 4. D: group mean response time data (last block of step 4), after replotting with respect to each participant's initially determined chunk points. E: correlation between response time ratio (the mean response time for the 1st element of the chunks divided by the mean response time for the remaining chunk elements) and mean chunk length. F: correlation between the decay constants for step 1 and mean chunk length. G: block at which participants formed their final chunking pattern during training in the transfer and nontransfer groups.

FIG. 4.

A: the accuracy data for each array size of the visuospatial working memory task are plotted for 2 representative participants. B: correlation between the decay constants for step 1 and working memory capacity (K). C: correlation between working memory capacity (K) and mean chunk length. D: the visuospatial working memory capacity in 3- and 4-chunk length groups.

FIG. 5.

Scatterplots showing the relationship between working memory capacity and CV 500 (A), CV 1,000 (B), and CV 1,500 (C). Scatterplots among the 3 timing intervals: CV 500 vs. CV 1,000 (D), CV 500 vs. CV 1,500 (E), and CV 1,000 vs. CV 1,500 (F).