Patterns of interference in sequence learning and prism adaptation inconsistent with the consolidation hypothesis

Abstract

The studies reported here used an interference paradigm to determine whether a long-term consolidation process (i.e., one lasting from several hours to days) occurs in the learning of two implicit motor skills, learning of a movement sequence and learning of a visuo-motor mapping. Subjects learned one skill and were tested on that skill 48 h later. Between the learning session and test session, some subjects trained on a second skill. The amount of time between the learning of the two skills varied for different subjects. In both the learning of a movement sequence and the learning of a visuo-motor mapping, we found that remote memories were susceptible to interference, but the passage of time did not afford protection from interference. These results are inconsistent with the long-term consolidation of these motor skills. A possible difference between these tasks and those that do show long-term consolidation is that the present tasks are not dynamic motor skills.

Figure 1

Experiment 1 RT during training and testing sessions for each condition. (A) Control; (B) 5-min; (C) 1-h; (D) 5-h; (E) 24-h. (□) Training on Sequence A; (○) training on Sequence B; (▪) testing on Sequence A. (Rs) Random blocks; (Ss) sequenced blocks. Error bars, +/− 1 SE. The measures of learning were taken when subjects performed the SRT task alone by subtracting performance in the S block from the average of that of the two R blocks.

Figure 2

Covariate-adjusted means of the (A) PI scores and (B) the RI scores for the RT measure in Experiment 1. PI scores were obtained by subtracting the Learning of A score from that for the Learning of B. RI scores were obtained by subtracting the Learning of A score from that for the Test of A. Negative values on these measures indicate interference. Positive values indicate positive transfer or retention.

Figure 3

Experiment 2 exposure performance across blocks during the training and testing sessions for each condition. (A) Control; (B) 5-min; (C) 5-h; (D) 24-h. (□) Training on Sequence A; (○) training on Sequence B; (▪) testing on Sequence A. Error bars, +/− 1 SE.

Figure 4

(A) Covariate-adjusted means for the PI scores on the measure of exposure performance. PI scores were obtained by subtracting subjects' Learning of B score from their Learning of A score. (B) Raw means for the RI scores on the measure of exposure performance. Error bars, +/− 1 SE. RI scores were obtained by subtracting subjects' Test of A score from their Learning of A score. Negative values on both the PI and RI measures indicate interference; positive values indicate either positive transfer or retention.

Figure 5

Experiment 2 aftereffects performance across blocks during the training and testing sessions for each condition: (A) Control; (B) 5-min; (C) 5-hr; (D) 24-hr. (□) Training on Sequence A; (○) training on Sequence B; (▪) testing on Sequence A. Negative values are indicative of a greater adaptation between the perception and action systems. Error bars, +/− 1 SE.

Figure 6

(A) Covariate-adjusted means for the PI scores on the measure of aftereffects performance. PI scores were obtained by subtracting subjects' Learning of B score from their Learning of A score. (B) Means for the RI scores of aftereffects performance. Error bars, +/− 1 SE. RI scores were obtained by subtracting subjects' Test of A score from their Learning of A score. Negative values on both the PI and RI measures indicate interference; positive values indicate either positive transfer or retention.