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Three experiments provide evidence that the perceived similarity between two images is systematically affected by the inherent direction of a transformation that links the two. Participants were shown short animations morphing one object into another from the same basic category. They were then asked to make directional similarity judgments ("How similar is object A to object B?") for two stationary images drawn from the morph continuum. Across three experiments, similarity ratings for identical comparisons were higher when the reference object, B, had appeared before the comparison object, A, in the preceding morph sequence. This response to dynamic transformational sequences is in accordance with the view that similarity depends on the ease of transformation between object representations and that transformations between objects in categorization and object recognition are psychologically real.

Over two experiments, we investigated the ability of two adolescent and two adult chimpanzees to generalise a learnt, pictorial categorisation to increasingly degraded and abstract stimuli. In Experiment 2, we further assessed the ability of the adolescent chimpanzees to engage in open-ended categorisation of black-and-white line drawings. The current results confirmed and extended previous findings, showing that sub-adult chimpanzees outperform adult chimpanzees in the categorisation of pictorial stimuli, particularly when the stimuli are more degraded and abstract in nature. However, none of the four chimpanzees showed positive transfer of their category learning to a set of black-and-white line drawings, and neither of the adolescent chimpanzees evidenced reliable open-ended categorisation of the black-and-white line drawings. The latter findings suggest that both sub-adult and adult chimpanzees find it difficult to recognise black-and-white line drawings, and that open-ended categorisation of black-and-white line drawings is challenging for chimpanzees.

This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent repository link:http://openaccess.city.ac.uk/4700/ Link to published version: http://dx.doi.org/10. 1080/17470218.2012.660963 Copyright and reuse: City Research Online aims to make research outputs of City, University of London available to a wider audience. Copyright and Moral Rights remain with the author(s) and/or copyright holders. URLs from City Research Online may be freely distributed and linked to. Keywords: Basic level; categorisation; object recognition; PDP; semantic dementia. Reversals of the Basic-Level Advantage 3 Rogers and Patterson (2007): a Parallel Distributed Processing accountHuman categorisation can take place at a number of different levels of abstraction:people may classify a set of objects at the superordinate level (e.g., animal, furniture), at the basic level (e.g., dog, chair), and/ or at the subordinate level (e.g., Labrador, armchair). In a seminal paper by Rosch, Mervis, Gray, Johnson and Boyes-Braem (1976), these authors reported a robust preference in humans for classification at the basic level, establishing that this level of abstraction has a 'special status' in human categorisation.For patients with the neurological disorder semantic dementia (SD), however, basic level and subordinate level conceptual knowledge is found to degrade, leaving only superordinate level knowledge relatively intact (see Warrington, 1975). In an intriguing paper by Rogers and Patterson (2007), these authors first replicated the robust basic level superiority effect in a healthy population (e.g., Hoffmann & Ziessler, 1983;Murphy & Brownell, 1985;Rosch et al., 1976;Tanaka & Taylor, 1991; see also Malt, 1995, for a cross-cultural perspective) and then demonstrated a reversal of the basic level advantage in four patients with severe SD: that is, superordinate level categorisation was found to be superior to that of basic level categorisation (henceforth, we refer to this as a superordinate level > basic level advantage; see also Hodges, Graham, & Patterson, 1995;. According to PDP theory, "knowledge about the meanings of words and objects emerges from the interactive activation of perceptual, motor, and linguistic representations across different modalities of reception and expression" (Rogers & Patterson, 2007, p. 456). It has been argued that these different kinds of sensorymotor information are coded in neuroanatomically distinct cortical regions, which converge in the anterior temporal cortex (the focus of the neuropathology in SD; e.g., Nestor, Fryer, & Hodges, 2006). That is, the anterior temporal lobes are seen to function as a kind of cross-modal "hub" for the interaction between these different types of representations. Semantic representations, then, are considered not to encode any explicit or directly interpretable content per se. Rather, the combination of our perceptual, motor, and linguistic representations give rise to the content of our semantic memory (Ba...

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