Mixed-complexity artificial grammar learning in humans and macaque monkeys: evaluating learning strategies.
Bottom Line: We found no significant sensitivity to the non-adjacent AG relationships in the macaques.The results suggest that humans and macaques are largely comparably sensitive to the adjacent AG relationships and their statistical properties.However, in the presence of multiple cues to grammaticality, the non-adjacent relationships are less salient to the macaques and many of the humans.
Affiliation: Institute of Neuroscience, Newcastle University, Henry Wellcome Building, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK; Centre for Behaviour and Evolution, Newcastle University, Newcastle upon Tyne, UK.Show MeSH
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Mentions: To investigate whether the macaques were sensitive to violations of the AG, we conducted a repeated‐measures (RM)‐anova with the dependent variable ‘response duration’, including the factors ‘condition’ (consistent and violation sequences) and ‘monkey’ (two levels). A main effect of ‘condition’ demonstrated that the monkeys responded more strongly to violations of the AG (F1,30 = 19.4, P < 0.001). There was no interaction between ‘condition’ and ‘monkey’ (F1,30 = 0.54, P = 0.819), suggesting that the results are consistent between both animals. Similar results were observed when the responses of each animal were analysed individually (paired‐samples t‐tests, M1: t15 = 3.628, P = 0.002; M2: t15 = 2.839, P = 0.012; Fig. 3A and B). To determine whether this effect could be attributed to the monkeys simply responding more strongly to sequences that were not present in the exposure phase, we conducted a second analysis separately comparing novel and familiar consistent sequences with the violation sequences (Fig. S2). An RM‐anova with the factors ‘condition’ (novel and familiar consistent sequences and violation sequences) and ‘monkey’ revealed a main effect of condition (F2,29 = 9.941, P = 0.001) and no interaction between the factors (F2,29 = 0.213, P = 0.809). Bonferroni‐corrected post hoc tests reveal no differences between the familiar and novel consistent sequences (P = 1.0), but showed large differences between responses to the violation sequences and the familiar (P = 0.001) and novel sequences (P = 0.005), respectively. This analysis suggests that the observed sensitivity to violation sequences generalises to novel consistent sequences, which were not heard by the animals during the exposure phase. This is consistent with the generalisation that we have previously seen in macaques with a different version of this AG learning paradigm (Wilson et al., 2013). The results demonstrate that the macaques are sensitive to violations of the AG, and that their responses cannot be attributed solely to the familiarity of the test sequences. Also, additional analyses confirmed that the response to the novel stimuli was stable throughout the testing runs (Supporting Information).
Affiliation: Institute of Neuroscience, Newcastle University, Henry Wellcome Building, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK; Centre for Behaviour and Evolution, Newcastle University, Newcastle upon Tyne, UK.