ABSTRACT

Since Warrington and Shallice’s (1984) first experi-mental paper on the topic, there have been numerous reports of patients with problems in recognising and naming objects belonging to particular categories of object. Most commonly patients have been reported with impaired recognition and naming of living things, but the opposite impairment, for nonliving things, has also been noted on several occasions (see Caramazza, 1998; Forde & Humphreys, 1999; Humphreys &, Forde, 2001; Tyler &, Moss, 2001, for recent reviews). These neuropsychological reports have been bolstered by converging evidence from normal observers studies, including: (1) studies using functional imaging to demonstrate differences in the neural substrates of recognition and naming for living and nonliving things (e.g., Chao, Haxby, & Martin, 1999; Devlin et al., 2003; Martin, Wiggs, Ungerleider, & Haxby, 1996; Perani, Schnur, Tettamanti, GornoTempini, Cappa, & Fazio, 1999; Spitzer et al., 1999; though see Devlin et al., 2002), (2) differences in event-related potential signals to stimuli from the different categories (Kiefer, 2001), and (3) differences in the efficiency of processing living and nonliving things (Humphreys, Riddoch, &, Quinlan, 1988; Lloyd-Jones & Humphreys, 1997). There have been claims that these differences may reflect artifactual variations in familiarity and image complexity (Funnell &. Sheridan, 1992; Stewart, Parkin, & Hunkin, 1992). However, the fact that double dissociations can occur (see Hillis & Caramazza, 1991), and that category effects remain even with covarying factors either controlled or factored out (Farah, Meyer, & McMullen, 1996;

Sartori, Miozzo, & Job, 1993), suggests that they are a real consequence of the different ways in which stimuli from contrasting categories are processed and neurally represented in the brain.