Everyday Examples of Mental Lexicon Representations

I had a conversation with a colleague the other day, which really made me laugh. I think most people would have found it funny! But I also found it fascinating – through my linguistics-tinted glasses 🙂

My colleague was talking about her old, lazy lodger, who was rather reluctant to do jobs around the house, even when he himself complained that they needed doing. She described the situation something like this:

He complains that it all needs doing, but he’s too lazy, he really does tiddly-winks!

Cue raucous laughter on my part. Tiddly-winks?? What does that have to do with being lazy? Once the laughter died down, it took us a minute or two to come up with the word she was actually looking for: He is lazy, he does diddly squat!  (i.e. nothing)

The conversation moved on, comparing the tiddly-winks guy to her new lodger. He, it seems, is much more active, and can’t stop tidying up and doing odd jobs around the place. Her description of him?

It’s almost obsessive. My psychologist friend says he probably a bit ACDC!

ACDC? The new synonym for hard-working? No. She of course meant OCD – well… it IS kind of similar!

Once again, laughter on both sides. I even had a chuckle to myself in the car on the way home when I remembered her great quotes! And then my linguist brain kicked in, and I remembered an interesting talk I’d heard recently at our English Linguists Circle about how lexis is represented in the brain, the mental lexicon. Like a light bulb pinging above my head, I realised that what had originally been an after-lunch natter on a slow day at the office, actually provided amusing examples of how our brains store and recall words.

Aitchison (“Words in the Mind”, 2003) explains that a word’s meanings and word class are separated from the sound of the word in the mental lexicon, because semantic knowledge is the most important trigger when activating words for production whereas phonology is the more important trigger in the recognition of words. In this scheme, word lemmas (i.e. with information about meaning and word class) are organised in semantic fields, which are held together by strong connections between coordinates of the same word class. A semantic field is a group of words which are used to talk about the same phenomenon – the words are sometimes hyponyms of a more general term.

A clear everyday example: If I say “knife”, what other words do you think of? Probably “fork” and “spoon”. These words form a set of semantically related items – all hyponyms of ‘cutlery’.

Ok, what about “red”, “yellow”, “pink”…? You probably think of “green”, “purple”, “orange”, “blue”, and a whole list of other colours. It should be  clear that these words are also members of a semantic field; they all belong to the same word class (they’re usually categorised as adjectives), and are all used to talk about the same phenomenon (colour).

In the examples from my colleague’s quotes, though, the confusion of words leading to her amusing slips does not seem to have come from the semantic organisation of her mental lexicon – although Aitchson says that this is most important for production. We know  that the meaning of “tiddly-winks” (a game, see here: http://en.wikipedia.org/wiki/Tiddlywinks), is not used to describe a phenomenon that is any way comparable to “diddly squat”, although they happen to both be nouns. So the confusion leading to the funny slips of the tongue must have its roots somewhere else.

According to Aitchison, a word’s phonological form, i.e. its sound structure, also influences how it is stored in the mental lexicon, with similar-sounding words organised together, in order to enable effective speech comprehension. For example, rhyming words such as “cat”, “rat”, “mat”, “bat” are easily misheard and confused with each other. Imagine being at a loud party and your friend shouts “Oh my gosh! Look, a rat!” It’s of course possible that with all the noise, you hear “Oh my gosh, you look fat!” But the comprehension of speech is highly dependent on contextual clues. We have all been in a situation where we think we have heard what someone has said, but still have the feeling that what we think has been said would not make sense, or be appropriate, in the given context. For example, it is unlikely, I imagine, that a friend with whom we have gone to a party would suddenly turn to us and shout that we are fat! We can either ask the person to repeat themselves, or we can figure it out on our own, by looking for similar-sounding words which might fit in the context of the conversation. Indeed, this is what linguists (and psychologsists for that matter) believe happens subconsciously all the time – put simply, recognition of lexical input is based on multiple factors from which our brain calculates the most likely intended meaning and so ‘triggers’ the activation of these items in the mental lexicon. Aitchison explains that similar words compete for activation, in recognition as well as in production, and sometimes the wrong one is chosen, which leads either to misunderstanding speech input, or making errors, like my colleague. That phonologically similar words are more difficult to recall has been shown by plenty of research (e.g. Copeland & Radvansky, 2001 / Yip, 2004): studies into this ‘phonological-similarity effect’ thus provide support for this idea that words compete to be used, and this can sometimes lead to blending or blocking errors, like tiddly-winks!

Another thing that makes these errors interesting is that, according to theories in the area, the more frequent an expression is the more likely are we to pick it over a less frequent one (i.e. more frequent words have greater memory strength). I’m not sure that a modern corpus would show ACDC as more frequently used than OCD … but (without wanting to psychoanalyse my colleague to much!), these errors seem to highlight how individuals’ “corpora” of linguistic reception are probably made up differently.

The question remains, then, of why my colleague’s production errors seem to have been caused by phonological similarity, although Aitchison says this is mostly used for recognition rather than production. Well, any models of the exact structure of the mental lexicon are sadly just that – models; vastly simplified versions of what they represent. But what is generally agreed upon is the fact that the mental lexicon has to strive for the most efficient compromise between the best organisation of representations for production and for recognition. So there’s something like a tug of war going on in our heads, with the optimum organisation for production competing against the optimum organisation for recognition – and don’t forget that the mental lexicon is also influenced by memory’s needs and other functions! My colleague herself admitted she was feeling tired on the day of our amusing chat, and the slips she made would seem to highlight two key points:

1) that the semantic and phonological representations of any item are not entirely separated, so that either type of representation may be used to activate a word for recognition or production. Although it may be the case (and indeed seems very logical if you look at how we approach finding a word that we want to say/write in a certain context) that semantic organisation is more helpful for production, it definitely is not the case the phonological representations play no role at all in the activation of lexical items for production.

2) that physical conditions can impaire the brain’s ability to direct and manipulate the usual decision-making mechanisms used to activate the correct lexical items – but that these breakdowns in normal service can actually reveal a lot about the mental lexicon and how we access it. We can find anecdotal as well as scientific evidence to support this idea .  I’ve recently read, for example, about schizophrenics’ language use, which highlights the competition going on within the mental lexicon (e.g. Obrebska & Obrebska, 2007). And, of course, my colleague’s tiredness led to some amusing examples, which can not only be used to cheer us up on a rainy February day, but also provide a little amusing insight into the wonders of the mental leprechaun… I mean, lexicon! 🙂

References

Aitchison, J., Words in the Mind: An Introduction to the Mental Lexicon (Blackwell, 2003)

Copeland, D. & G. Radvansky, “Phonological Similarity in Working Memory”, Memory & Cognition, 2001, 29 (5), 774-776. Accessed at http://www3.nd.edu/~memory/Reprints/Copeland%20&%20Radvansky%202001%20(Memory%20&%20Cognition).pdf on 20.2.2014

Obrebska, M. & T. Obrebska, “Lexical and grammatical Analysis of Schizophrenic Patients’ Language: A Preliminary Report”, Psychology of Language and Communication, 2007, Vol. 11, No. 1, 63-72. Accessed at http://www.plc.psychologia.pl/plc/plc/contents/fulltext/11-1_4.pdf on 20.2.2014.

Yip, M.C.W., “What is similar in phonological-similarity effect?, School of Arts & Social Sciences, The Open University of Hong Kong, 2004. Accessed at http://www.cogsci.northwestern.edu/cogsci2004/ma/ma155.pdf on 20.2.14

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Is there a Critical Period for Language Learning?

Psychologists, linguists and teachers have all long debated the manner in which a child acquires language and the existence of a critical period, that is “a period of time during which an organism is optimally ready for the acquisition of specific responses”, here language (Reber & Reber, 2001). Originally, the discussions centred around first language (L1) acquisition, but of course this debate has relevance for ELT and other foreign language teachers!

The hypothesis of a biologically based critical period for language was first overtly suggested by Lenneberg (1967), and asserts that if no language has been learnt by the onset of puberty, it can never be learned in a normal and functional sense. This post will present and evaluate the evidence Lenneberg and later supporters of the critical period hypothesis have cited to verify their ideas, in order to provide an answer to the question as to whether or not a critical period exists for acquisition of language.

As the idea of a critical period was most prominently advanced by Lenneberg, let’s first look at the evidence he cited. His argument can be broken down into two parts. Firstly, that normal language learning occurs primarily (if not exclusively) during childhood. Evidence for this assumption was drawn from studies of brain damage recovery; children who suffer brain damage before puberty typically recover fully and (re-)develop normal language ability, whereas adults rarely recover fully, and often do not regain verbal abilities beyond the point reached five months after impairment (Hurford, 1991, p. 159). Secondly, Lenneberg supports Penfield & Roberts’ (1959) proposal that humans possess a neurological mechanism responsible for this maturational change in language learning abilities: after puberty, the brain loses its ‘plasticity’ and the re-organisational capacity needed for language learning. This coincides with lateralisation of the brain and the specialisation of the left hemisphere for language. In children motor and linguistic skills develop simultaneously, but between the ages of two and thirteen years, the functions of the cerebral hemispheres separate and become fixed, rendering the acquisition of language difficult, if not impossible (Lenneberg, 1967, pp. 389-90).

However, this neurological explanation has,been challenged by later work. Witelson & Pallie (1973), for example, maintained that lateralisation is complete by the age of five years. Krashen (1975) reanalysed the clinical data used as evidence (e.g. from Genesee, 1978), and also concluded that lateralisation was complete much earlier than Lenneberg calculated, therefore the link between lateralisation and the end of a critical period is rendered somewhat unconvincing, considering children can easily learn languages up to the age of about twelve years: if a critical period does exist, it does not coincide with lateralisation.

Despite the concerns with Lenneberg’s original evidence, and the dissociation of lateralisation from the idea of a critical period for language acquisition, the concept of the biologically based critical period remains in itself a viable hypothesis, for which later, more direct and reliable evidence has been cited. This more recent evidence, from studies of feral children, congenitally deaf children, and second language acquisition, will now be discussed.

Feral children are those who were not exposed to human language as a child because of being brought up in the wild (possibly by animals), in isolation and/or in confinement. One early case of this kind is of ‘Victor’ (Itard, 1801). Victor was found aged twelve by a physician who tried for five years to teach him to speak and read. Victor learned to understand many words, but never learned to speak himself.  Possibly the most famous example of such case studies is that of ‘Genie’ (Curtiss, 1977). Genie was deprived of social interaction for the first thirteen years of life, because her father judged her as retarded and isolated her from birth. On her discovery she was completely without language, and even after seven years of rehabilitation she still lacked linguistic competence. A similar case study is of ‘Isabelle’, who was incarcerated in a dark room with her deaf-mute mother until the age of six and a half. Although she had learned to communicate with her mother through a system of gestures, when found she had no formal language skills. Unlike Genie, with the specialist attention of psychologists and systematic training, Isabelle quickly acquired normal language ability (Davis, 1949). All of these cases support Lenneberg’s critical period hypothesis: Victor and Genie were both discovered after puberty and did not acquire normal language, whereas Isabelle, who was found before puberty, developed full linguistic competence. This demonstrates that children require exposure to language and normal social interaction before a certain age to acquire language themselves. Critics of the critical period hypothesis, though, highlight that the children in these studies grow up in generally abusive environments, suffering emotional trauma and seclusion, and may have been isolated due to general retardedness; therefore their lack of language acquisition may be the result of these factors, rather than a lack of exposure to language.

Studies of congenitally deaf children have also been applied to support the critical period hypothesis. Newport & Supalla (1987) studied language acquisition in deaf children whose development was otherwise normal, but who were exposed to sign language at different ages: because 90% of children had hearing parents, very few were exposed to sign language from birth, in fact most first learnt it at school. Newport & Supalla’s results showed a “linear decline in performance with increasing age of exposure, on virtually every morpheme tested” (1995, p. 78), that is to say that those exposed to sign language from birth performed best, and ‘late learners’ worst, on all tests of production and comprehension. This study thus provides direct evidence for language learning ability decreasing with age.

As it is often difficult to directly test the critical period in native language acquisition, mainly due to ethical objections, many researchers have turned to the area of second language acquisition to clarify and refine the critical period hypothesis. Indeed, this is the research that is probably of most interest to language teachers. If, as an extreme interpretation of the critical period suggests, “the biological fact of adulthood is enough to establish an insurmountable obstacle” to comprehensive language acquisition (Seliger, 1978, P. 11), then adults should find it almost impossible to learn a second language. Asher & Garcia (1969) substantiate this belief with their study of Cuban immigrants, which showed that children who had arrived in the U.S. aged between one and six did much better on a test of reading English than those were aged seven to nineteen years on arrival.

Nonetheless, studies of foreign language learning and the application of their data to first language acquisition has been questioned by some researchers. The extent to which first and second language acquisition are similar forms the basis for this counter-argument, but it also highlights the different circumstances under which younger and older language students learn languages, including the amount of exposure and nature of instruction, if any.

Aside from the biological view of a critical period, Chomsky (1965)’s theory of language acquisition based on a ‘transformational grammar’ has been used to explain why children acquire language easily. Initially, the ‘learner’ possesses innate principles und rules which build a ‘black box’ in the brain. These principles denote restricted possibilities for variation within the target language, and enable the learner to construct a grammar from the ‘raw input’ collected from the environment. Although he did not name a specific period for optimal language learning, it has been drawn from Chomsky’s ideas that younger children can learn languages more easily than older children or adults. The theory maintains that children can learn several languages simultaneously, as long as their ‘black box’ principles are still active. Adults would have to use the same principles developed at a young age for language acquisition to re-learn language (e.g. after brain damage) or to learn a foreign language, and will therefore have more difficulty in doing so.

Yet another view, the behaviourist approach, argues that language is learned in the same way as other behaviours; through learning reactions to environmental stimuli by conditioning or imitation. The theorists who first applied this idea to language acquisition are Skinner (1957) (concerned with classical conditioning) and Mowrer (1960) (concerned with imitation and operant conditioning). New connections between behaviour and the environment are formed and reformed throughout life and it follows that it is possible to gain new skills, including language(s), at any age. Although Skinner and Mowrer do not discuss the question of a critical period for language directly, some theorists (e.g. Felix, 1985) have drawn from their ideas that children, whose brains create countless new connections every day, will simply cope better with (re-)learning a language than adults. This assumption is however untested and can not be taken as an explanation of the ease with which children acquire language in comparison to adults. The biggest criticism this theory faces, is that it assumes that all learning, whether verbal (languages) or non-verbal (general learning), takes place through the same habit forming processes (Chomsky, 1969).

In summary then, the hypothesis of a critical period for language acquisition is not a new idea. Since it was hinted at by Penfield & Roberts and vigorously advocated by Lenneberg, a biological base of the idea has been thoroughly researched and, to a certain extent, validated by the results of studies, such as those by Newport & Supalla, Curtiss and Asher & Garcia. Although the evidence comes from a variety of areas, namely feral children, deaf children and second language acquisition, no one study can provide critic-free conclusive evidence. The feral children’s lack of language may be due to abusive environments; deaf children do not show total incapability for language learning once they reach puberty; and second language learning studies rely on a questionable generalisation of their data to native language acquisition. Despite this, all the studies discussed here do demonstrate differences between younger and older learners of a language, and the majority of theorists agree that children have an advantage over adults in language acquisition.

Biological and neurological approaches are not the only tools to explain this age different in language learning abilities. Chomsky’s language acquisition theory of transformational grammar has also been applied to this purpose, as have Skinner’s and Mower’s behaviourist ideas. Both approaches have some solid supporting evidence, but also weaknesses and disadvantages. The problem faced by all theories and studies is that they seem to focus on just one aspect of the relationship between language acquisition and age; in order to completely prove the existence of a critical period for language acquisition a theory would need to be able to explain the maturational changes as well as the general language acquisition process.

It seems then, that evidence generally supports the notion of a period prescribed by age where language is more easily learned, but with some considerable modifications to Lenneberg’s initial idea, and with various explanations. One modification that has often been discussed is the ‘weakening’ of the concept to a sensitive period. This is a period where “an organism is sensitive to particular forms of stimulus inputs and physiologically and psychologically ready for the acquisition of a particular response”, here language (Reber & Reber, 2001). This would mean learning a language is easier as a child, but does not imply that later learning is out of the question, rather that it is more difficult. Indeed, the various studies and approaches discussed here point to the likelihood of a period with relatively steep, but not absolutely abrupt boundaries. As Hurford explains, “the evidence available seems to indicate a curve [in language learning ability] which rises early, maintains a high level before puberty, and the falls, with the steepest downward slope coinciding roughly with puberty.” (p. 160). This idea is clearly evidenced by Newport & Supalla’s results, and by the fact that students of foreign languages do not experience complete failure after puberty, and makes many theories and approaches to explaining language acquisition more feasible.

In answer to the specific question of whether there is a critical period, then, it seems sensible to conclude that, as Lenneberg and others suggest, there is an optimal window of opportunity for language acquisition, but this is more correctly labelled as a sensitive period, rather than a critical one.

 

References

• Asher, J. & Garcia, R. (1869). The optimal age to learn a foreign language. Modern Language Journal, 53, 334-341.

• Chomsky, N. (1965). Aspects of the Theory of Syntax. Cambridge: MIT Press

• Chomsky, N. (1969). Linguistics and Philosophy. In S. Hook (ed). Language and Philosophy. New York: New York U. P.

• Clark, E. V. (2003). First Language Acquisition. Cambridge: Cambridge U. P.

• Curtiss, S. (1977). Genie: A Psycholinguistic Study of a Modern Day “Wild Child”. New York: Academic Press.

• Davies, K. (1949). Human Society. New York: MacMillan.

• Felix, S. (1985). More evidence on competing cognitive systems. Second Language Research, 1 (1), 47-72.

• Genesee, F. (1978). Is there an optimal age for starting second language instruction?. Mc Gill Journal of Education, 13,145-54.

• Hurford, J. R. (1991). The evolution of the critical period for language acquisition. Cognition, 10,  159 – 201.

• Itard, J. M. G. (1801). De l’education d’un homme savage ou des premiers développements physiques et moraux du jeune sauvage d’Aveyron.Paris: Goyon.

• Johnson, J. S. & Newport, E.L. (1995). Critical Period Effects in Second Language Learning: The Influence of Maturational State on the Acquisition of English as a Second Language. In Brown, H. D. & Gonzo, S. (eds). Readings on Second Language Acquisition. Englewood Cliffs, NJ: Prentice Hall.

• Krashen, S. D. (1975). The critical Period for language acquisition and its possible bases. In Aaronson, D. & Rieber, R W. (eds). Developmental Psycholinguistics and communication disorders. New York: N. Y. Academy of Sciences.

• Lenneberg, E. (1967). Biological Foundations of Language. New York: Wiley.

• Lest, G. (1981). Sprachpsychologie. Stuttgart: Stuttgart U. P.

• Newport, E. L. & Supalla, T. (1987). A Critical Period Effect in the Acquisition of a Primary Language. University of Illinois, manuscript under review, cited in Johnson, J. S. & Newport, E.L. (1995).

• Penfield, W. & Roberts, L. (1859). Speech and Brain Mechanisms. Princeton, NJ: Princeton U. P.

• Purves, D., Augustine, G. J., Fitzpatrick, D., Katz, L. C., Anthony-Samuel, L., McNamara, J. O. & Williams, S. M. (2001). Neuroscience, 2^nd Edition. Sunderland, MA: Sinauer.

• Schöpfung, U. (1977). Psychologie des Erst- und Zweitspracherwerbs: Eine Einführung. Stuttgart: Kohlhammer.

• Seliger, H. W. (1978). Implications of a multiple critical periods hypothesis for second language learning. In Richie, W. C. (ed). Second Language Acquisition Research: Issues and Implications. New York: Academic Press.

• Snow, C. & Hoefnagel-Hohle, M. (1978). The critical period for language acquisition. Child Development, 49, 1114-1128.

• Whitaker, H. A., Bub, D. & Leventer, S. (1981). Neurolinguistic aspects of language acquisition and bilingualis. In Winitz, H. (ed). Native Language and Foreign Language Acquisition. New York: N. Y. Academy of Sciences

• Witelson, S. F. & Pallie, W. (1973). Left hemisphere specialization for language in the newborn. Brain, 96, 641-646.