The neural, evolutionary, developmental, and bodily basis of metaphor

Abstract

We propose that there are four fundamental kinds of metaphor that are uniquely mapped onto specific brain “networks” and present preliterate (i.e., evolutionary, including before the appearance of written language in the historical record), prelinguistic (i.e., developmental, before the appearance of speech in human development), and extralinguistic (i.e., neuropsychological, cognitive) evidence supportive of this view. We contend that these basic metaphors are largely nonconceptual and entail (a) perceptual–perceptual, (b) cross-modal, (c) movement–movement, and (d) perceptual-affective mappings that, at least, in the initial stages of processing may operate largely outside of conscious awareness. In opposition to our basic metaphor theory (B_mT), the standard theory (S_mT) maintains that metaphor is a conceptual mapping from some base domain to some target domain and/or represents class-inclusion (categorical) assertions. The S_mT captures aspects of secondary or conceptual metaphoric relations but not primary or basic metaphoric relations in our view. We believe our theory (B_mT) explains more about how people actually recognize or create metaphoric associations across disparate domains of experience partly because they are “pre-wired” to make these links.

Introduction

We propose that there are four fundamental kinds of metaphor that are uniquely mapped onto specific brain “networks” and present preliterate (i.e., evolutionary, including before the appearance of written language in the historical record), prelinguistic (i.e., developmental, before the appearance of speech in human development), and extralinguistic (i.e., neuropsychological, cognitive) evidence supportive of this view. We contend that these basic metaphors are largely nonconceptual and entail (a) perceptual–perceptual, (b) cross-modal (synesthetic), (c) movement–movement, and (d) perceptual-affective mappings that, at least, in the initial stages of processing may operate outside of conscious awareness. That is, they are informationally encapsulated (Fodor, 1983), “pre-wired” (Marcus, 2004), and probably universal across human populations (Brown (1991), Brown (1999), Brown (2000)). In opposition to our basic metaphor theory (B_mT), the standard theory (S_mT) maintains that metaphor is a conceptual mapping from some base domain to some target domain (e.g., Gentner, Holyoak & Kokinov, 2001; Lakoff & Johnson, 1980) and/or represents class-inclusion (categorical) assertions (e.g., Glucksberg, 2003).

For instance, Gentner and colleagues (Gentner et al., 2001; Gentner & Markman, 1997) argue that similarity, including metaphoric similarity as well as analogy, involves a process of “structure alignment”—a one-to-one correspondence between mapped elements and “systematicity”—a matching of connected systems of relations. Metaphors, however, map both systems of relations (e.g., atomic structure is like a solar system) and attributes of objects (e.g., “His hand was like a vise”) depending on the type of the metaphor. This differentiation of similarity, however, conflates analogy with metaphor and B_mT theory suggests that metaphor is a separate species, at least for the metaphorical relations subsumed by it. On the other hand, Glucksberg and colleagues (Glucksberg, 2003; Glucksberg & Keysar, 1993) contend that metaphors are more properly thought of as “implicit class-inclusion relations.” For instance, the metaphorical statement, “Cigarettes are time bombs,” is a class-inclusion assertion in which the terms, “cigarettes” and “time bombs” are absorbed under the superordinate category, “time bombs.” Nevertheless, what is left out of both of these accounts is how people actually go about selecting which relations, which attributes or which terms to attend to in the first place.

While Glucksberg and colleagues maintain that metaphoric statements are apprehended as ordinary language—“quickly and automatically”—it would appear that metaphor comprehension probably occurs in conscious awareness because it involves, among other things, ongoing decisions about how to respond to mutually constituted social interactions (e.g., Speaker A: “Cigarettes are time bombs.” Speaker B: “Yes, I stopped smoking several years ago”); although the authors do not confront this thorny aspect of metaphoric language—that it often serves some conscious social purpose. Indeed, Gentner and colleagues indicate that analogy and metaphor involve more abstract conceptual relations and presumably entail some conscious mechanisms.

People make analogical and metaphoric inferences based on higher-order connecting relations (p. 239).

Similar accounts are found elsewhere in the literature and are widespread, i.e., metaphor involves the mapping of conceptual domains at high levels of abstraction and entails some conscious mechanisms (e.g., Fauconnier & Turner (1998), Fauconnier & Turner (2002); Lakoff & Johnson, 1980). Lakoff (1993), however, suggests that conceptual metaphor is largely unconscious and automatic like ordinary language and this largely unconscious substrate of our conceptual system “contains thousands of conventional metaphorical mappings” (p. 245). We criticize this view below under “Alternative Theories of Early Metaphor.” In any event, the nonconscious mechanisms operating outside awareness are notoriously difficult to pin down (Allen & Reber, 1998).

To be sure, consciousness deals with situations that require novel and nonstereotypical responses. Nonconscious mechanisms, however, function to deal with stereotypical forms of behavior conditioned by evolution for immediate and efficient use (Koch, 2004; Searle, 2005). We propose that the kinds of basic metaphoric relations in B_mT are largely nonconscious and automatic: Notwithstanding individual differences, we might easily perceive a plate of spaghetti as a collection of worms or a stop sign as a popsicle (perceptual–perceptual metaphors), a spinning top as a ballerina (movement–movement metaphor), a front of a car as smiling (perceptual-affective metaphor) or music as sad (cross-modal metaphor; see Seitz (2001a), Seitz (2005)). That is, they involve extensive automaticity including implicit perception, memory, and thought; they are fast and independent (Marcus, 2004); they are engaged by specific environmental stimuli; and they are largely innate (Kihlstrom (1987), Kihlstrom (2002); see below). Cytowic (2002a), Cytowic (2002b) makes a related case for synesthesia arguing that that it is automatic, involuntary, and inborn.

S_mT thus captures aspects of secondary or conceptual metaphoric relations but not primary or basic metaphoric relations in our view. We think our theory B_mT explains more about how people actually create or recognize metaphoric associations across disparate domains of experience partly because they are “pre-wired” to make these links. That is, we propose that humans have specialized neural subsystems for metaphoric understanding and production that are fine-tuned by experience and continuously modulated by underlying genetic mechanisms (Marcus, 2004).

The fundamental ability to link disparate sensory, perceptual, enactive, and affective domains can be described as an inter-, poly-, or multisensory ability or supra-, trans-, hetero- or multimodular capacity (Calvert, 2001, Seitz, 1997). That is, these basic metaphoric relations (B_mT) rely on central sensory, perceptual, and affective mechanisms that relate percepts and affects across dissimilar psychological domains based on relations within and between brain areas or “networks” (see below). For instance, biological constraints in the maturation of the intersensory areas in the mid- and frontal areas of the brain underlie synesthetic metaphor or the ability to link disparate sensory modalities (Marks, 1996; Marks & Bornstein, 1987; Marks, Hammeal, & Bornstein, 1987; Ramachandran & Hubbard (2001a), Ramachandran & Hubbard (2001b)).

Similarly, we have shown that the ability to link the physical and psychological domains (“psychological–physical metaphor;” Cicone, Gardner, & Winner, 1981) is based on the earlier ability to attribute affective properties to inanimate objects or what we have called “physiognomic metaphor” (Seitz, 1998b; Seitz & Beilin, 1987). For instance, whereas synesthetic metaphor is largely biological constrained, appears to derive from an inborn sense of similarity or comparison, and relies less on learning and development—that is to say, is largely intuitive (see below)—psychological–physical metaphor violates category boundaries based on learned conceptual relations (whether from informal experience or formal learning) and the probable rejection (whether conscious or not) of cultural and linguistic conventions. This is, at least, true of novel metaphors if not conventional ones (Gentner et al., 2001) as Quinn (1991) has argued: Metaphors are typically chosen by speakers because they are already part of existing cultural understandings.

Nevertheless, the ability to relate the perceptual and affective domains originates in the biological capacity to impute affective properties to inanimate and animate objects (Seitz & Beilin, 1987). Autistic children who lack this capacity are unable to attribute affective properties to social or nonsocial objects or use or apprehend metaphoric language (Baron-Cohen, Leslie, & Frith, 1985; Leslie & Frith, 1988; Seitz, 1996)—notwithstanding Kanner's (1946) earlier but incorrect use of the term “metaphoric language” in autistic children (see Seitz, 1996)—as are brain damaged adults with alexithymia (Brothers, 1989) and adults with forms of prosopagnosia in which there is damage to anterior regions of area V4 in the inferior temporal lobe that underlie both affective recognition and expression in the face (Zeki, 1999).