Evidence for Orthographic Processing in Baboons (Papio papio)? A Visual Familiarity Account

Grainger, Dufau, Montant, Ziegler, and Fagot (2012a) taught six baboons to discriminate words from nonwords in an analogue of the lexical decision task. The baboons endorsed novel words more readily than novel nonwords, and had trouble rejecting nonwords that were orthographically similar to learned words. In a subsequent test (Ziegler, Hannagan, et al., 2013), the same animals demonstrated the transposed-letter effect. All three results are often taken as hallmarks of orthographic processing in skilled human readers. We show by simulation of the unique learning trajectory of each of the baboons that the results can be interpreted equally well as an example of simple, familiarity-based discrimination of pixel-maps, without orthographic processing.