BEYOND COMMUNICATION: LANGUAGE MODULATES VISUAL PROCESSING

Understanding the extra-communicative functions of language (e.g., Clark, 1998) is central for constraining theories of language evolution. If, in addition to its communicative functions, language has extra-communicative functions—affecting nonverbal cognitive and perceptual processes—then an important force in the evolution of language may have been the effect language had and continues to have on such processes. Such reasoning helps to address a question central to the evolution of language: what adaptive benefits did early language users derive from rudimentary linguistic systems?

In the present work I will present an overview of the past 4 years of research in which we find that, across a range of paradigms, language exerts a rapid and automatic influence on basic visual processes. These results provide (indirect) evidence that even in rudimentary forms, language systems may have conferred basic perceptual (and non-communicative) benefits to their users.

A critical aspect of human development is the development of conceptual and perceptual categories—learning that things with feathers tend to fly, that animals possessing certain features are dogs, and that foods of a certain color and shape are edible (Rogers & McClelland, 2004; Keil, 1992; Carey, 1987). This conceptual acquisition is, in principle, separable from the acquisition of language (a child can have a conceptual category of "dog" without having a verbal label associated with the category). However, in practice the two processes appear to be intimately linked. Not only does conceptual development shape linguistic development (Snedeker & Gleitman, 2004), but linguistic development, specifically learning words for things, appears to be impact conceptual development (Gentner & Goldin-Meadow, 2003; Lupyan, Rakison, & McClelland, 2007; Waxman & Markow, 1995). The empirical findings in the present work argue that such effects of language are not limited to long-term effects on conceptual development. It is argued that language exerts a on-line modulatory role on even the most basic perceptual processes.

The data come from standard paradigms from the vision sciences: visual search, mental rotation, cued target-detection, simple detection, and picture verification. These experiments license the following broad conclusions:

1. Hearing a category label such as "chair" facilitates the visual processing of the named category compared to trials on which participants know the relevant object category but do not actually hear its name. In some instances, producing the verbal label has similar facilitatory effects (Lupyan, 2007, 2008b, under review).

2. The above effects are transient, having a characteristic temporal profile, and are heavily modulated by the typicality of the visual exemplar. Visual processing of more typical items is more facilitated by hearing their name (Lupyan, 2007; 2008b; under review).

3. Hearing a label increases the perceptual saliency of the named category, enabling people to detect objects that are otherwise invisible (Lupyan & Spivey, 2008; under review).

4. Very brief amounts of training can alter the associations between labels and object categories suggesting that, at least in adults, such linguistic modulation of perception is highly flexible (Lupyan, 2007; Lupyan, Thompson-Schill, & Swingley, in press).

Ongoing work is showing that verbal labels evoke associated perceptual representations faster and more reliably than nonverbal stimuli. For example, people activate the visual properties of a cat faster when they hear the word "cat" than when they hear a meowing sound. Specifically, it appears that verbal labels come to have a special status of being able to activate categorical representations.

This linguistic modulation of perception may have important consequences for higher-level cognition such as the learning of new categories (Lupyan et al., 2007), memory (Lupyan, 2008), and conceptually grouping items along a particular dimension (e.g., color) (Lupyan, 2009) as well as inference in reasoning.

Theories of language evolution have maintained an almost exclusive focus on the communicative aspects of language. The present findings show that simple word-object pairings can modulate even basic visual processes, providing support for the idea that even in its early stages, languages may have conferred cognitive and perceptual benefits on their users.

Note from Publisher: This article contains the abstract only.