When people speak, they often insinuate their intent indirectly rather than stating it as a bald proposition. Examples include sexual come-ons, veiled threats, polite requests, and concealed bribes. We propose a three-part theory of indirect speech, based on the idea that human communication involves a mixture of cooperation and conflict. First, indirect requests allow for plausible deniability, in which a cooperative listener can accept the request, but an uncooperative one cannot react adversarially to it. This intuition is sup- ported by a game-theoretic model that predicts the costs and benefits to a speaker of direct and indirect requests. Second, language has two functions: to convey information and to negotiate the type of relationship holding between speaker and hearer (in particu- lar, dominance, communality, or reciprocity). The emotional costs of a mismatch in the assumed relationship type can create a need for plausible deniability and, thereby, select for indirectness even when there are no tangible costs. Third, people perceive language as a digital medium, which allows a sentence to generate common knowledge, to propagate a message with high fidelity, and to serve as a reference point in coordination games. This feature makes an indirect request qualitatively different from a direct one even when the speaker and listener can infer each other’s intentions with high confidence.

Why do compounds containing regular plurals, such as rats-infested, sound so much worse than corresponding compounds containing irregular plurals, such as mice-infested? Berent and Pinker (2007) reported five experiments showing that this theoretically important effect hinges on the morphological structure of the plurals, not their phonological properties, as had been claimed by Haskell, MacDonald, and Seidenberg (2003). In this note we reply to a critique by these authors. We show that the connectionist model they invoke to explain the data has nothing to do with compounding but exploits fortuitous properties of adjectives, and that our experimental results disconfirm explicit predictions the authors had made. We also present new analyses which answer the authors’ methodological objections. We conclude that the interaction of compounding with regularity is a robust effect, unconfounded with phonology or semantics.

This paper proposes a new analysis of indirect speech in the framework of game theory, social psychology, and evolutionary psychology. It builds on the theory of Grice, which tries to ground indirect speech in pure rationality (the demands of e‰cient communication between two cooperating agents) and on the Politeness Theory of Brown and Levinson, who proposed that people cooperate not just in exchanging data but in saving face (both the speaker’s and the hearer’s). I suggest that these theories need to be supple- mented because they assume that people in conversation always cooperate. A reflection on how a pair of talkers may have goals that conflict as well as coincide requires an examination of the game-theoretic logic of plausible denial, both in legal contexts, where people’s words may be held against them, and in everyday life, where the sanctions are social rather than judi- cial. This in turn requires a theory of the distinct kinds of relationships that make up human social life, a consideration of a new role for common knowledge in the use of indirect speech, and ultimately the paradox of ra- tional ignorance, where we choose not to know something relevant to our interests.

English speakers disfavor compounds containing regular plurals compared to irregular ones. Haskell, MacDonald and Seidenberg (2003) attribute this phenomenon to the rarity of compounds containing words with the phonological properties of regular plurals. Five experiments test this proposal. Experiment 1 demonstrated that novel regular plurals (e.g., loonks-eater) are disliked in compounds compared to irregular plurals with illicit (hence less frequent) phonological patterns (e.g., leevk-eater, plural of loovk). Experiments 2–3 found that people show no dispreference for compounds containing nouns that merely sound like regular plurals (e.g., hose-installer vs. pipe-installer). Experiments 4–5 showed a robust effect of morphological regularity when phonological familiar- ity was controlled: Compounds containing regular plural nonwords (e.g., gleeks- hunter, plural of gleek) were disfavored relative to irregular, phonologically-iden- tical, plurals (e.g., breex-container, plural of broox). The dispreference for regular plurals inside compounds thus hinges on the morphological distinction between irregular and regular forms and it is irreducible to phonological familiarity.

The role of Broca’s area in grammatical computation is unclear, because syntactic processing is often confounded with working memory, articulation, or semantic selection. Morphological processing potentially circumvents these problems. Using event-related functional magnetic resonance imaging (fMRI), we had 18 subjects silently inflect words or read them verbatim. Subtracting the activity pattern for reading from that for inflection, which indexes processes involved in inflection (holding constant lexical processing and articulatory planning) highlighted left Brodmann area (BA) 44/45 (Broca’s area), BA 47, anterior insula, and medial supplementary motor area. Subtracting activity during zero inflection (the hawk; they walk) from that during overt inflection (the hawks; they walked), which highlights manipulation of phonological content, implicated subsets of the regions engaged by inflection as a whole. Subtracting activity during verbatim reading from activity during zero inflection (which highlights the manipulation of inflectional features) implicated distinct regions of BA 44, 47, and a premotor region (thereby tying these regions to grammatical features), but failed to implicate the insula or BA 45 (thereby tying these to articulation). These patterns were largely similar in nouns and verbs and in regular and irregular forms, suggesting these regions implement inflectional features cutting across word classes. Greater activity was observed for irregular than regular verbs in the anterior cingulate and supplementary motor area (SMA), possibly reflecting the blocking of regular or competing irregular candidates. The results confirm a role for Broca’s area in abstract grammatical processing, and are interpreted in terms of a network of regions in left prefrontal cortex (PFC) that are recruited for processing abstract morphosyntactic features and overt morphophonological content.

The distinction between singular and plural enters into linguistic phenomena such as morphology, lexical semantics, and agreement and also must interface with perceptual and conceptual systems that assess numerosity in the world. Three experiments examine the computation of semantic number for singulars and plurals from the morphological properties of visually presented words. In a Stroop-like task, Hebrew speakers were asked to determine the number of words presented on a computer screen (one or two) while ignoring their contents. People took longer to respond if the number of words was incongruent with their morphological number (e.g., they were slower to determine that one word was on the screen if it was plural, and in some conditions, that two words were on the screen if they were singular, compared to neutral letter strings), suggesting that the extraction of number from words is automatic and yields a representation comparable to the one computed by the perceptual system. In many conditions, the effect of number congruency occurred only with plural nouns, not singulars, consistent with the suggestion from linguistics that words lacking a plural affix are not actually singular in their semantics but unmarked for number.

In my book How the Mind Works, I defended the theory that the human mind is a naturally selected system of organs of computation. Jerry Fodor claims that ‘the mind doesn’t work that way’ (in a book with that title) because (1) Turing Machines cannot duplicate humans’ ability to perform abduction (inference to the best explanation); (2) though a massively modular system could succeed at abduction, such a system is implausible on other grounds; and (3) evolution adds nothing to our under- standing of the mind. In this review I show that these arguments are flawed. First, my claim that the mind is a computational system is different from the claim Fodor attacks (that the mind has the architecture of a Turing Machine); therefore the practical limitations of Turing Machines are irrelevant. Second, Fodor identifies abduction with the cumulative accomplishments of the scientific community over millennia. This is very different from the accomplishments of human common sense, so the supposed gap between human cognition and computational models may be illusory. Third, my claim about biological specialization, as seen in organ systems, is distinct from Fodor’s own notion of encapsulated modules, so the limitations of the latter are irrelevant. Fourth, Fodor’s arguments dismissing of the relevance of evolution to psychology are unsound.