Sense of Accomplishment Is Modulated by a Proper Level of Instruction and Represented in the Brain Reward System

<div><p>Problem-solving can be facilitated with instructions or hints, which provide information about given problems. The proper amount of instruction that should be provided for learners is controversial. Research shows that tasks with intermediate difficulty induce the largest sense of accomplishment (SA), leading to an intrinsic motivation for learning. To investigate the effect of instructions, we prepared three instruction levels (No hint, Indirect hint, and Direct hint) for the same insight-problem types. We hypothesized that indirect instructions impose intermediate difficulty for each individual, thereby inducing the greatest SA per person. Based on previous neuroimaging studies that showed involvement of the bilateral caudate in learning and motivation, we expected SA to be processed in this reward system. We recruited twenty-one participants, and investigated neural activations during problem solving by functional magnetic resonance imaging (fMRI). We confirmed that the Indirect hint, which imposed intermediate difficulty, induced the largest SA among the three instruction types. Using fMRI, we showed that activations in the bilateral caudate and anterior cingulate cortex (ACC) were significantly modulated by SA. In the bilateral caudate, the indirect hint induced the largest activation, while the ACC seemed to reflect the difference between correct and incorrect trials. Importantly, such activation pattern was independent of notations (number or letter). Our results indicate that SA is represented in the reward system, and that the Indirect instruction effectively induces such sensation.</p></div

Activations in the correct and incorrect trials.

<p>Beta estimates of correct and incorrect trials were extracted from the anatomically defined ROIs (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0168661#pone.0168661.s007" target="_blank">S7 Fig</a>) of the left caudate (A, D), right caudate (B, E), and ACC (C, F), for both problem-solving period and answer-feedback period. *<i>P</i> < 0.05. **<i>P</i> < 0.01. ***<i>P</i> < 0.001. Error bars, SD.</p

Activation modulated by SA in the answer-feedback period.

<p>The cortical activation map was projected onto the sagittal plain (uncorrected <i>P</i> < 0.001). See Table B in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0168661#pone.0168661.s015" target="_blank">S1 File</a> for the stereotactic coordinates.</p

Behavioural data for the four conditions.

<p>Accuracy (A), RT (B), and SA (C) are shown for the four conditions (two notations concatenated). (D) SA in the correct and incorrect trials, averaged across No hint, Indirect, and Direct conditions. *<i>P</i> < 0.05. **<i>P</i> < 0.01. ***<i>P</i> < 0.001. Error bars, SD.</p

Effect of intrinsic problem difficulty.

<p>Accuracy (A) and RT (B) for three instruction levels are shown as a function of intrinsic problem difficulty (Difficulty). (C) SA for the three difficulty levels, divided according to the RT differences for each participant. (D) The average number of trials for each of three instructions included in each difficulty level. ***<i>P</i> < 0.001. Error bars, SD.</p

Experimental design.

<p>One of the four types of instructions was presented for 1 s, followed by the problem stimulus. Participants performed Number/Letter completion or button-press control tasks during the 5 s interval. After 1 s of a blank screen, 3 s of correct-answer feedback stimulus was presented. After the feedback stimuli, the participants rated their sense of accomplishment (SA) during the 3 s interval. Here we have shown an example of a Number notation task (translated in English).</p

Activation modulated by SA only for the correct trials.

<p>Neural activations parametrically modulated by SA, only for the correct trials. The cortical activation map was projected onto the coronal (A) and sagittal (B) plains (uncorrected <i>P</i> < 0.001). See Table C in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0168661#pone.0168661.s015" target="_blank">S1 File</a> for the stereotactic coordinates.</p