Figure 3.

Implicit arousal-related memory boost eliminated by noradrenaline blockade. a, Rare performance-independent rewards led to increased arousal as measured by a larger pupil dilation after rewarded (compared with non-rewarded) trials. The effect arose ∼2 s after reward presentation in all groups (horizontal lines: cluster-level significant group effects p < 0.05 using permutation tests). b, The arousal-related rewards immediately following word presentation during incidental memory phase led to improved subsequent recognition. This effect was present both after placebo and dopamine blockade, but not after noradrenaline blockade. c, The arousal-induced memory boost was not explicit. When subjects were asked to explicitly indicate which words were rewarded (source memory task), they did not perform above chance (dashed line) and the groups did not differ in their performance. Our findings suggest that the implicit arousal-induced memory boost primarily depends on β-adrenoceptor functioning. n.s., p > 0.05, *p < 0.05.