An Investigation of the Influence of Language on Colour Perception.

Benjamin Whorf (1921) proposed that the language we speak affects the way we see and think about the world. Some recent theories (e. g. Lupyan, 2010) have suggested that language may be able to actively affect perception by top-down feedback or by permanent changes to the visual system. Colour perception has provided a furtive testing ground for this Whorfian debate. Research has indicated that colour categories in language (colour terms) may actually affect perception by causing colours from different categories to become easier to discriminate than equivalently different colours from the same category. Recently, three lines of evidence have supported the argument that these category effects are Whorfian. First, it has been argued that category effects in colour perception are lateralised to the language dominant left hemisphere (the ‘Lateralised Whorf effect proposed by Gilbert et al. , 2006). Second, studies have found that category effects are eliminated when participants are required to verbally rehearse nonsense words whilst discriminating colours (verbal interference). Third, there is evidence for cross-linguistic differences in category effects, including neurophysiological evidence for these differences. This thesis systematically investigates these three lines of evidence in a series of experiments, and aims to test assumptions, add adequate control conditions, and approach the issue from new angles. Chapter 1 reviews the evidence and background to the contemporary debate. Chapter 2 presents a series of experiments which further investigated the ‘Lateralised Whorf effect. Serious issues were found with the validity underlying this effect and the findings suggest it may in fact arise from a natural bias in attention allocation rather than an influence of language. Chapter 3 examines the effects of verbal interference with findings suggesting that verbal interference is not a reliable method to infer the involvement of language in perceptual processing. Chapter 4 explores cross-cultural differences in colour category effects. Category effects for Greek and English speakers were compared for a lexical distinction present in the Greek colour lexicon that is absent in English. In a series of experiments, including an event-related potential study, no effects of language on colour processing were found. Overall, the findings question the role of language in the early perceptual processing of colour. Whorfian effects may be restricted to memory effects and interactions with response processes. The thesis has implications for the fundamental issue of how language and perception interact more generally