Praise Enhances Offline Skill Improvements Figure 2. Manipulation of praise. (A) The sequence of events in the movie. The introduction clip was followed by 12 evaluation clips in a fixed order. After each evaluation clip, the participant was asked to rate their subjective happiness using a seven-point scale. (B) The instructions and the introduction clip differed between the Self and Other groups. In the Self group, participants were told that the movies represented an evaluation of their own training performance. Participants in the Other group were told that the movies represented the evaluation of another participant’s performance. (C) The subjective judgment of participant happiness using a seven-point scale (1 = very unhappy, 4 = neutral, 7 = very happy). Error bars indicate the standard error of the mean (SEM). *p,0.05 (unpaired two-tailed t-test). The subject of the photograph has given written informed consent, as outlined in the PLoS consent form, to publication of their photograph. doi:10.1371/journal.pone.0048174.g002 was directed, it is unlikely that any physical components in the video clips induced the observed group differences. In addition, other potential factors such as alertness, concentration, fatigue, and quality and duration of sleep did not differ between the groups, so cannot explain the improved consolidation in the Self group. An alternative explanation of the present result is that praise induces a positive mood or increases the motivation to perform the motor task [5,7,10], resulting in the greater improvement in Figure 3. Results. (A) Mean performance during the last three training trials on day 1 (LRN1) and the first three retest trials on day 2 (LRN 2). All groups showed offline improvements on the trained sequence. (B) The rate of offline improvement, the percent increase from LRN1 to LRN2, was significantly greater in the Self group than the Other and No-praise groups. Black, gray, and white points or bars represent the Self, Other, and No- praise groups, respectively. Error bars indicate the standard error of the mean (SEM). *p,0.05 (Dunnett’s test). doi:10.1371/journal.pone.0048174.g003 PLOS ONE | www.plosone.org 3 November 2012 | Volume 7 | Issue 11 | e48174