Exp Brain Res (2011) 211:601–612 difference between mean Compatible and Incompatible reaction times at each time bin was entered into a 3 9 2 9 2 ANOVA with factors of Speed (Fast, Medium, Slow), Age Group (Adult, Adolescent) and Prime Group (Pro-social, Non-social). As Mauchley’s test of sphericity was signiﬁcant, degrees of freedom were corrected using the Greenhouse-Geisser method. Results of this ANOVA revealed a signiﬁcant Speed x Age Group x Prime Group Interaction (F(1.2, 97.7) = 6.0, P = 0.01). Inspection of the means (Fig. 4) of each condition at each of the time bins suggests that the effect of pro-social priming is seen only in the Adult Group at the slowest reaction times. The interaction between Speed, Age and Prime Group was decomposed by performing ANOVAs with factors of Age and Prime Group at each of the 3 time bins. There was a signiﬁcant interaction between Age and Prime Group at the slowest time bin (F(1,83) = 6.0, P = 0.01), but not at the medium (F(1,83) = 2.7, P = 0.10), or fast time bins (F(1,83) \ 1), although the interaction approached signif- icance at the medium time bin. These analyses were fol- lowed-up with univariate ANOVAs with a between-groups factor of Prime Group at each combination of the Speed and Age Group factors. The effect of Prime Group was not signiﬁcant for any time bin in the Adolescent Group (all Ps [ 0.244). The effect of Prime Group was not signiﬁcant in the Adult Group at the fastest time bin (F(1,54) = 1.7, P = 0.2), approached signiﬁcance at the medium time bin, (F(1,54) = 2.9, P = 0.09), and was signiﬁcant at the slowest time bin (F(1,54) = 6.4, P = 0.01). Discussion Previous research has demonstrated that in adults priming a positive social attitude in comparison with a negative social Fig. 4 Social priming affects slow, but not medium or fast, responses in adult participants. This suggests that social priming affects the inhibition of imitative responses 609 attitude promotes imitation (Leighton et al. 2010). Since social attitudes and the social brain are changing through- out the adolescent years, the aim of this study was to test whether pro-social attitudes promote imitation in an Ado- lescent Group to the same extent as in an Adult Group. In agreement with the results of Leighton et al., we found that adults who had been primed with words promoting pro-social attitudes (e.g. friend, crowded, team, talkative) showed a greater Imitation Effect than adults who had been primed with words promoting non-social attitudes (e.g. himself, solo, one, private). The difference in the degree of modulation of imitation by social priming was signiﬁcantly greater for adults than for adolescents. Indeed, there was no signiﬁcant difference between the amount of imitation shown by adolescents primed with pro-social words com- pared with adolescents primed with non-social words. It is unlikely that the inefﬁcacy of pro-social priming on imitation for the Adolescent Group is due to an ineffective pro-social priming technique. The prime words in the Priming task were selected on the basis that they feature in the common vocabulary of both adolescent and adult par- ticipants. Throughout the testing sessions, none of the participants questioned the deﬁnition of the words. Fur- thermore, statistical analyses demonstrated that for all groups the average error rate on the Priming task did not exceed 2 of 32 sentences, and there was no signiﬁcant difference between the error rates generated by the four groups. Hence, all groups were able to use the scrambled words to create a grammatically correct sentence. The associative sequence learning model (Heyes 2001, 2003; Heyes and Ray 2000; Brass and Heyes 2005) sug- gests that imitation is mediated by low-level mechanisms in which activation of a sensory representation of a body movement (e.g. by visual attention to that movement) necessarily results in activation of a motor representation of the same movement (and thereby an impulse to perform the movement), provided that the sensory and motor rep- resentations have become linked through previous, corre- lated experience of observing and executing the movement. In principle, social attitudes could modulate imitation via an attentional route—by inﬂuencing the probability that sensory representations of body movement will be acti- vated (see also Teufel et al. 2010)—or via an inhibitory route—by inﬂuencing the degree to which activation of motor representations by associated sensory representa- tions is suppressed to prevent overt performance of the represented movement (see also Liepelt and Brass 2010). Leighton et al. (2010) argue that positive social attitudes most likely promote imitation via an inhibitory route rather than an attentional route. They argue that the attentional route is less likely since imitation tasks such as the one used in the current experiment require attention to the same part of the screen as the movement stimuli (i.e. in the 123