RESEARCH REPORT The representation of conceptual knowledge: visual, auditory, and olfactory imagery compared with semantic processing Massimiliano Palmiero • Rosalia Di Matteo • Marta Olivetti Belardinelli Received: 6 December 2012 / Accepted: 11 October 2013 / Published online: 12 December 2013 Ó Marta Olivetti Belardinelli and Springer-Verlag Berlin Heidelberg 2013 Abstract Two experiments comparing imaginative pro- cessing in different modalities and semantic processing were carried out to investigate the issue of whether con- ceptual knowledge can be represented in different format. Participants were asked to judge the similarity between visual images, auditory images, and olfactory images in the imaginative block, if two items belonged to the same cat- egory in the semantic block. Items were verbally cued in both experiments. The degree of similarity between the imaginative and semantic items was changed across experiments. Experiment 1 showed that the semantic pro- cessing was faster than the visual and the auditory imagi- native processing, whereas no differentiation was possible between the semantic processing and the olfactory imagi- native processing. Experiment 2 revealed that only the visual imaginative processing could be differentiated from the semantic processing in terms of accuracy. These results showed that the visual and auditory imaginative processing can be differentiated from the semantic processing, although both visual and auditory images strongly rely on semantic representations. On the contrary, no differentia- tion is possible within the olfactory domain. Results are discussed in the frame of the imagery debate. Keywords Imagery Á Semantic representation Á Sensory modality Introduction How people represent conceptual knowledge is a long- debated issue. One important approach posits that con- ceptual knowledge is distributed across different attribute domains, such as vision, touch, and olfaction (e.g., Allport 1985; Barsalou 1999). Thus, the distinction between visual knowledge and non-visual knowledge has been drawn (see Thompson-Schill 2003, for a review), leading to the claim that visual knowledge is represented differently from non- visual knowledge. This claim is tied to the question of which format is used to store and represent information. In this direction, the investigation into the nature of mental imagery can shed light on the representation of conceptual knowledge. Indeed, it is assumed that access to conceptual knowledge is necessary in order to create a mental image (e.g., Kan et al. 2003). Thus, the central question is the extent to which mental imagery relies on perceptual rep- resentations, as opposed to propositional representations. According to perceptual theories (e.g., Kosslyn et al. 2006), imagery and perception share common mechanisms and processes. Different studies revealed imagery–per- ception interference (e.g., Craver-Lemley and Arterberry 2001; Perky 1910; Segal and Fusella 1970) and imagery– perception facilitation (e.g., McDermott and Roediger 1994) in visual modality, suggesting that visual images and visual percepts share the same system of information M. Palmiero (&) Department of Life, Health and Environmental Sciences, University of L’Aquila, L’Aquila, Italy e-mail: massimiliano.palmiero@univaq.it R. Di Matteo Á M. O. Belardinelli ECONA, Interuniversity Centre for Research on Cognitive Processing in Natural and Artificial Systems, Rome, Italy R. Di Matteo Department of Neuroscience and Imaging, ‘‘G. d’Annunzio’’ University, Chieti, Italy M. O. Belardinelli Department of Psychology, ‘‘Sapienza’’ University of Rome, Rome, Italy 123 Cogn Process (2014) 15:143–157 DOI 10.1007/s10339-013-0586-9