Improvements to visual working memory performance with practice and feedback

Abstract

Visual working memory capacity is estimated to be around 3-4 items, but on some trials participants fail to correctly report even a single item from the memory array. Such failures of working memory performance are surprisingly common, and participants have poor self-awareness of them. Previous work has shown that behavioral feedback can reduce the frequency of working memory failures, but the benefits of feedback disappeared immediately after it was taken away. Here, we tested whether extended practice with or without trial-by-trial feedback would lead to persistent improvements in working memory performance. Participants were assigned to one of four groups: (1) Working memory practice with feedback (2) Working memory practice without feedback (3) Crossword puzzle active control (4) No-contact control. Consistent with previous work, simple practice with a visual working memory task robustly improved working memory performance across practice sessions. However, we found only partial support for the efficacy of feedback in improving working memory performance. Practicing with feedback improved working memory performance relative to a no-feedback group for some practice sessions. However, the feedback benefits did not persist across all training sessions and did not transfer to a final test session without the feedback. Thus, the benefits of performance feedback did not persist over time. Further, we found only stimulus-specific transfer of visual working memory practice benefits. We also found that participants' metaknowledge improved with practice, but that receiving feedback about task accuracy actually slightly harmed the accuracy of concurrent metaknowledge ratings. Finally, we discuss important design considerations for future work in this area (e.g. power, expectations, and "spacing effects"). For example, we found that achieved statistical power to detect a between-groups effect declined with practice. This finding has potentially critical implications for any study using a 1-session study to calculate power for a planned multi-session study.

Fig 1. Trial procedures for the color whole report task.

Key trial events are depicted from left to right. Participants remembered the locations and colors of 6 squares across a blank delay, then reported the color at each location by clicking a color in “response grids” with the mouse. The arrangement of colors in the response grids was the same for all trials and all participants.

Fig 2. Improvement in practiced task over time.

(A) Change in mean number correct for the working memory task. (B) Change in proportion less than 3 correct for the working memory task. (C) Change in crossword puzzle performance (words per minute). Error bars represent one standard error of the mean.

Fig 3. Improvement in working memory metaknowledge with practice.

(A) Metaknowledge correlation metric. Higher correlation values indicate better metaknowledge. (B) Absolute value of the difference between confidence and accuracy on each trial. Values closer to 0 represent better metaknowledge. Error bars represent one standard error of the mean.

Fig 4. Change in performance from pre-test to post-test for practiced tasks and working memory measures.

(A) Color whole report (B) Crossword puzzles (C) Color change detection (D) Orientation whole report.

Fig 5. Change in performance from pre-test to post-test.

(A) Antisaccade accuracy (B) Visual search average reaction time (C) Raven’s Matrices.

Fig 6. Difference in subjective effort and perceived improvement across groups.

(A) Average subjective effort rating. (B) Average perceived improvement rating. Ratings were made on a scale from 1 to 6. In this plot, 6 represents the highest level of endorsement of effort and improvement.