Psychon Bull Rev DOI 10.3758/s13423-017-1362-0 THEORETICAL REVIEW Phonemes: Lexical access and beyond Nina Kazanina1 & Jeffrey S. Bowers1 & William Idsardi 2 # The Author(s) 2017. This article is an open access publication Abstract Phonemes play a central role in traditional theories the rejection of phonemes is based on a false analysis and a as units of speech perception and access codes to lexical rep- too-narrow consideration of the relevant data. resentations. Phonemes have two essential properties: they are ‘segment-sized’ (the size of a consonant or vowel) and ab- stract (a single phoneme may be have different acoustic Keywords Access codes to lexicon . Lexical access . Lexical realisations). Nevertheless, there is a long history of challeng- representation . Phonemes . Phonological form . Speech ing the phoneme hypothesis, with some theorists arguing for perception . Speech segmentation . Units of speech perception differently sized phonological units (e.g. features or syllables) and others rejecting abstract codes in favour of representations that encode detailed acoustic properties of the stimulus. The Within traditional linguistic theory, phonemes are units used phoneme hypothesis is the minority view today. We defend to represent the ‘the psychological equivalent of a speech the phoneme hypothesis in two complementary ways. First, sound’ (Baudouin de Courtenay, 1972,p.152,)orthe we show that rejection of phonemes is based on a flawed psychophonetic or ideal sound forms of words also known interpretation of empirical findings. For example, it is com- as ‘phonological forms’ (Sapir, 1921, p. 55). Phonemes play monly argued that the failure to find acoustic invariances for a central role in explaining a large range of linguistic phenom- phonemes rules out phonemes. However, the lack of invari- ena, from historical changes in pronunciation of words to di- ance is only a problem on the assumption that speech percep- alectal variation to children’s speech or to how morphemes or tion is a bottom-up process. If learned sublexical codes are words change when they combine into a larger sequence. modified by top-down constraints (which they are), then this From a wider perspective that includes speech processing, argument loses all force. Second, we provide strong positive the traditional view ascribes to phonemes two additional prop- evidence for phonemes on the basis of linguistic data. Almost erties. On the speech production side, phoneme-based phono- all findings that are taken (incorrectly) as evidence against logical representations should be translatable into a set of phonemes are based on psycholinguistic studies of single articulatory-motor control processes (Guenther, 2016). On words. However, phonemes were first introduced in linguis- the speech perception side, phonemes should be extractable tics, and the best evidence for phonemes comes from linguis- from an acoustic signal and serve as access codes to words tic analyses of complex word forms and sentences. In short, (i.e. it should be possible to map an acoustic signal to a se- quence of phonemes in order to access lexical representations in long-term memory). This latter idea has been challenged by * Nina Kazanina speech-perception theorists who claim that there are no acous- [email protected] tic invariances that characterize phonemes across contexts that allow speech stream to be parsed into phonemes (A. M. 1 School of Experimental Psychology, University of Bristol, 12a Priory Liberman 1996), and by researchers who fail to obtain empir- Road, Bristol BS8 1TU, UK ical evidence for phonemes (Perkell & Klatt 1986). Indeed, 2 Department of Linguistics, University of Maryland, 1401 Marie many theories and models of spoken word identification es- Mount Hall, College Park, MD 20742, USA chew phonemes in favour of alternative sublexical access Psychon Bull Rev codes, for example, position-specific allophones or (demi-) between a sound form (aka ‘phonological form’)andamean- syllables. ing, as well as morphosyntactic properties of the word, such as In this article we consider conceptual and empirical chal- grammatical category, gender, and so forth. Words (aka lexical lenges to the phoneme. One common feature of these criti- entries) are stored in the lexicon, a long-term memory repos- cisms is that they are predominantly advanced in the context itory for words and significant subword parts (morphemes). of theories addressing monomorphemic single-word identifi- Understanding how phonological forms of words are cation. Yet a key consideration for units of lexical representa- stored in the lexicon is key for any theory of language. The tion is that they should be able to support linguistic computa- boundary conditions are that a language user should be able to tions across all levels of linguistic processing (A. M. recognise the phonological forms of words during speech Liberman, 1998). Indeed, the listener’sultimategoalisnot comprehension and utter them appropriately in language pro- to identify sublexical units or single words but to understand duction. A traditional answer from linguistic theory (Dresher, the meaning of any one of a boundless number of novel 2011;Jones,1950;Sapir,1921) is that words are represented phrases and sentences (Hickok & Poeppel, 2007; Pisoni & in long-term memory as sequences of phonemes, that is, ab- Luce, 1987). This involves recognising derived or inflected stract and discrete symbolic units of a size of an individual forms of words and establishing and interpreting grammatical speech segment, such as a consonants or vowel (yet not iden- relations between words or phrases. Even a simple phrase tical to them). A phonological form of a word is an ordered such as John’sdogrequires establishing a relation between sequence of phonemes, for example, the sequence of pho- the possessive John’s (constructed by the syntax and not nemes /k/ - /æ/ - /t/ (more succinctly, /kæt/) refers to a stored in the lexicon) and the base John (stored in the lexicon). meowing domesticated feline animal or /d∧k/ to a quacking The access codes to words need to support transparency of avian. Apart from special cases such as homonymy or poly- relations like this. Thus, we reconsider the claims made in the semy, two words that are distinct in meaning differ in phono- context of single words (Part 2) and pay special attention to logical form, with a minimal difference being exactly one arguments in favour of phonemes derived from linguistic anal- phoneme within the same position in the word (e.g. /kæt/ ysis of more complex items (Part 3). It is the linguistic argu- ‘cat’ vs. /mæt/ ‘mat’). Furthermore, different words can em- ments that provide the strongest evidence for the psychologi- ploy the same set of phonemes but in different orders (e.g. cat cal reality of phonemes as access units in speech perception /kæt/ vs. act /ækt/ vs. tack /tæk/). A language typically uses a that can support further language comprehension. repertoire of a few dozens of phonemes that are combined to The organisation of the article is as follows. Part 1 defines produce all of the thousands of word forms. the phoneme from the perspective of linguistic theory and An essential property of the phoneme is that it is abstract. discusses which properties it must have in order to enable an Individual instances of consonants and vowels are not pho- interface between lexical representation and their acoustic and nemes as such, but rather an articulatory or acoustic realisation articulatory-motor counterparts. Part 2 discusses conceptual of a phoneme. The claim that phonemes are ‘segment-sized’ and empirical challenges to the claim that phonemes serve as thus reflects the idea that each phoneme maps to a consonant sublexical access codes to phonological word forms. On alter- or vowel segment (i.e. ‘phone’) when the phonemic represen- native views, the sublexical units are items other than pho- tation is uttered (although, in some cases this mapping may be nemes or phonemes are artefacts of an alphabetical reading obscured by phonological processes; Chomsky & Halle, system. In each case, we show that the rejection of phonemes 1968). That phonemes are more abstract than phones is evi- as a general feature of speech perception is unjustified. Part 3 dent by comparing forms such as /kæt/ ‘cat’ and /d∧k/ ‘duck’, provides a set of arguments for indispensability of the pho- which both contain the phoneme /k/ even though it is realised neme from various linguistic phenomena, ranging from single as two different phones—an aspirated [kh]incat and a plain or words to phrases. Indeed, phonemes were first proposed out of unreleased [k˺]induck. This exemplifies a more general point: linguistic considerations, and linguistic evidence continues to phonemes may be realised via different phones depending on provide the best evidence for their existence. Part 4 discusses a the position within the syllable or word, on the neighbouring way of including phonemes into models of speech processing. sounds, on whether the phoneme occurs within a stressed or unstressed syllable, and other factors. So, the American English phoneme /t/ is realized as an aspirated [th] syllable- Part 1: Defining the phonemic code initially as in top, as an unaspirated [t] following /s/ as in star, or as an unreleased [t˺] in the syllable-final position as in cat. A considerable share of the speaker’s linguistic knowledge is The above statement is an instance of a phonological rule of knowledge about words. An average speaker retains knowl- American English whereby an abstract, context- and/or edge of tens of thousands of distinct word forms that enable position-independent phoneme /t/ is related to its allophones reference to a wide range of objects, properties and events. ([tʰ], [t], or [t˺]) that are context- and/or position-dependent. Most generally, knowing a word amounts to knowing the link Across languages phonemes may be realised via different Psychon Bull Rev phones; for example, in (European) French /t/ is not realised as ‘bonding’ in Goldstein & Fowler 2003)—phonological struc- [th] (Caramazza & Yeni-Komshian, 1974).