Error, praise, action and trait : effects of feedback on cognitive performance and motivation

Detta är en avhandling från Stockholm : Karolinska Institutet, Dept of Clinical Neuroscience

Sammanfattning: This thesis investigates the role of trial-based feedback on cognitive performance and motivation. We conducted behavioural tests in the laboratory, functional magnetic resonance imaging (fMRI) to investigate brain activation, and experimentally controlled tests in a non-lab environment; the classroom. In study I, we explored the effects of trial-based feedback in a working memory (WM) task. We used a factorial design so that we could study twelve different sequences that varied systematically in external and no external feedback on errors and correct responses. The feedback was delivered as brief sounds. We found that external feedback on errors did not impact on accuracy or reaction time (RT) in this test, which suggests a well-functioning internal error monitoring system. When external feedback was given on the first correct response after an error, we found reductions in performance accuracy. This implies that a sound given at this point may disturb the participants’ consolidation of strategy changes. When external feedback was given on all correct responses, participants responded more quickly. This was likely due to more information being extracted from the feedback about their responses being correct or incorrect, as revealed using information theoretical computations. As a result, performance accuracy decreased. In study II and III, we followed children’s WM training program in school. We started with a group of 112 children randomised into one of four feedback groups; 1) feedback on correct responses; 2) feedback on incorrect responses; 3) no feedback and 4) feedback on correct and incorrect responses. The feedback was delivered as brief sounds as well as occasional verbal sentences. Out of the initially 112 recruited children, only 53 completed ≥20 sessions of WM training. In study II, we investigated if intrinsic motivation and mindset regarding intelligence, contributed to the completion of ≥20 sessions of WM training, since mindset and intrinsic motivation has been suggested to influence motivation to continue with tasks. There was a significant difference in mindset scores between the children who performed ≥20 sessions of training and the children who did not. Mindset scores were lower in the group completing the training, meaning that these children to a greater extent viewed intelligence as something that can change with the help of training. Intrinsic motivation was measured by taking an average of seven chosen questions measuring motivation. A significant positive correlation was found between the motivation score and number of trained sessions. For example, we found that expectations of the training being fun and useful correlated positively with number of trained sessions. Since only half of the recruited participants completed ≥20 sessions of WM training, we recruited more participants to investigate the effects of trial-based feedback for study III. In study III, we recruited in total 177 children, of whom 133 performed ≥20 sessions of WM training. We investigated the effects of feedback on WM improvement, motivation and effort. We also used a new measure of effort as calculated from the number of trials the participants trained close to their max scores. We found an effect of feedback on WM improvement, where the least improvement was found in the group receiving feedback on both errors and corrects (Group 4). This effect of feedback on WM improvement was not mediated by effort. We found that high motivation and having high WM at the start had a positive impact on effort. This suggests that effort scores may be a good complement to measure motivation to train WM. Our results point towards a mechanism where trial-based feedback influences the performance monitoring system. Feedback related to a person’s trait has been shown to influence long-term development of an entity mindset, where intelligence is viewed as something that does not change with training. In study IV, we wanted to investigate if feedback in the form of praise related to a person’s trait (you are clever) and feedback related to a person’s action (your choice was correct) influenced performance improvements in a shorter perspective. Using fMRI, we measured brain activation patterns as a result of feedback type. This was a within-subject design where participants received both types of feedback at separate visits. We found that trait feedback, when compared to action feedback, reduced motivation, increased stress and impacted negatively on performance improvements. Caudate nucleus and medial prefrontal cortex were found to be more active in the trait condition. Interestingly, this effect was specific for more difficult trials that suggest that trait and task praise can impact on individuals’ task attention and level of uncertainty. In conclusion, adding to previous research regarding the contradictory effects of feedback, this thesis suggests that trial-based error-feedback does not interfere with a person’s internal feedback system, unless combined with positive feedback. Negative effects were found when the praise was related to trait or when positive feedback was given in excessive amounts, possibly interfering with the attentional resources needed for the task. Previous research on praise has found negative long-term effects of trait praise and here we found that it may also have immediate short-term effects.

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