Adjective conjunction as a window into the LATL’s contribution to conceptual combination

Abstract

Though a large literature implicates the left anterior temporal lobe (LATL) for combinatory operations, recent MEG studies have suggested that it is specifically involved in the composition of complex concepts, rather than syntactic or semantic composition in a more general sense. To further specify the computational contribution of the LATL, we tested whether LATL effects as observed in MEG require a situation in which features combine to form a single coherent entity representation or whether the relevant computation simply requires the attribution of features to a set but not necessarily to the same members of the set. Under the former hypothesis, the LATL would be sensitive to the number of features added to the representation of a single entity whereas under the latter account, LATL activity would reflect the total number of features integrated across different members of a set. To test this, we employed conjunctions of two adjectives whose lexical semantics were varied such that they either allowed or disallowed the attribution of their denoted properties to the same members of a set, i.e., the properties were either compatible or incompatible. The compatible properties resulted in so-called intersective and the incompatible in so-called collective readings. Our results show that the LATL tracks the number of features attributed to an individual as opposed to the number of features attributed to a set. Interestingly, the reverse pattern was found in the right ATL, demonstrating that although this region often shows parallel effects to the LATL, its functional contribution is clearly distinct.