mind, brain, and literacy: biomarkers as usable knowledge for education

MIND, BRAIN, AND EDUCATION

Mind, Brain, and Literacy:Biomarkers as UsableKnowledge for EducationUsha Goswami1

ABSTRACT—Neuroscience has the potential to make somevery exciting contributions to education and pedagogy.However, it is important to ask whether the insights fromneuroscience studies can provide ‘‘usable knowledge’’ foreducators. With respect to literacy, for example, currentneuroimaging methods allow us to ask research questionsabout how the brain develops networks of neurons specializedfor the act of reading and how literacy is organized in the brainof a reader with developmental dyslexia. Yet quite how thesefindings can translate to the classroom remains unclear. Oneof the most exciting possibilities is that neuroscience coulddeliver ‘‘biomarkers’’ that could identify children with learningdifficulties very early in development. In this review, I willillustrate how the field of mind, brain, and education mightdevelop biomarkers by combining educational, cognitive, andneuroscience research paradigms. I will argue that all threekinds of research are necessary to provide usable knowledgefor education.

Traditionally, the term ‘‘biomarker’’ (an objectively measurablebiological marker) has referred to plasma or protein products,for example, in cerebral spinal fluid (e.g., high levels of tauprotein in the early stages of Alzheimer’s disease). However,a biomarker can also be a neuroimaging signature, such asthe underactivation of a certain neural network or a cognitivesignature, such as the cognitive measures of early decline(e.g., impaired memory function) that are strongly associatedwith Alzheimer’s disease (Beddington et al., 2008). Thesedevelopments offer a window of opportunity for the field of

1Centre for Neuroscience in Education, University of Cambridge

Address correspondence to Professor Usha Goswami, Centre forNeuroscience, Faculty of Education, 184 Hills Rd, Cambridge CB2 8PQ,UK; e-mail: [email protected]

mind, brain, and education. The identification of biomarkersfor educational skills like reading and mathematics offersthe potential for the field of neuroscience to contributeusable knowledge to education. However, it is not clearthat the field is sufficiently advanced to identify biomarkersbased on protein products. I will argue here that, asmind and brain are intimately related, a robust cognitivemarker may in fact have more utility or ‘‘usability’’ forthe field than a cerebral marker. Nevertheless, neurosciencehas a key role to play in identifying cognitive biomarkers,because neuroscience can offer unique insights into causaldevelopmental mechanisms.

In this review, I will try to illustrate how neurosciencemethods can make a critical contribution to the mind,brain, and education field by deepening our understandingof causal mechanisms. Taking the critical precursor skillfor literacy of phonological awareness as an example, Iwill show how an integrated research program can helpus to understand the developmental mechanisms that leadto a learning difficulty such as developmental dyslexia.Developmental dyslexia is usually characterized as a specificproblem with reading and spelling that cannot be accountedfor by low intelligence, poor educational opportunities, orobvious sensory or neurological damage. Once it becomespossible to agree on the underlying causal mechanisms thatgive rise to specific problems, the field of mind, brain,and education will have the tools to develop a range ofbiomarkers for identifying the learning difficulty in question.For developmental dyslexia, these could include biomarkersat the level of brain structure (e.g., Niogi & McCandliss,2006), brain function (e.g., Eden & Zeffiro, 1998), genes (Daleet al., 1998), and cognition (e.g., Goswami et al., 2002). Ascognitive markers are typically cheaper to administer thanmarkers that rely on neural imaging or the extraction ofprotein products, the most useful ‘‘usable knowledge’’ foreducation may be better cognitive measures for identifyingeducational risk. My essential argument is that cognitivemeasures will be based on firmer foundations if the neural

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Usha Goswami

basis of the learning difficulty has been thoroughly investigatedand understood.

I will therefore adopt a narrow focus for this review basedon phonological awareness, the child’s awareness of the soundstructure of words. Phonological awareness has been found topredict reading acquisition in all languages so far studied.I will argue that if we can isolate the neural processesthat underpin the development of phonological awareness,this would provide usable knowledge for education. First,it would enable the development of biomarkers to testfor the risk of reading difficulties (a robust biomarkershould be usable with preverbal children and should notrequire attention skills). Discovery of a reliable markerwould enable language-focused remediation to be offeredearly in the developmental trajectory, long before the onset ofschooling, and thus long before the child experienced readingfailure (Goswami, 2008). Second, detailed information aboutdevelopmental causal mechanisms at the neural level shouldilluminate the developmental processes that would benefitmost from direct intervention. In my view, educationprovides the best form of intervention for learning difficulties.Increased understanding of underlying causal mechanismsshould therefore enable the design of optimal interventionsand optimal early reading curricula for all children. Finally,measurement of critical developmental neural processes inpre-test versus post-test designs (with appropriate controlgroups) should allow the unambiguous assessment of whetheran intervention or a general teaching program is makinga difference.

A second aim of this review is to illustrate that anarrow research focus does not preclude the building ofbridges between mind–brain and education. I will there-fore finish by considering how neuroscience research pro-grams could in the future enable recommendations froma ‘‘neuroscience-enriched’’ educator concerning the timing,sequence, differentiation, and methods of instruction in theearly teaching of reading. I will argue that important firststeps are (a) neuroscientific investigation of basic auditoryprocessing in order to understand the neural mechanismsunderpinning the development of phonological awareness;(b) investing in studies that are longitudinal, beginning ininfancy; (c) deepening our knowledge about brain responsesto simple auditory events, with the aim of developing simplebiomarkers; (d) eventually including all kinds of learners inthe research, with comparisons between typically developingand atypically developing children over developmental timebeing particularly important; and (e) regarding methods, rec-ognizing the need to ‘‘start small,’’ with (in this case) tractableresearch questions about sensory mechanisms that neverthe-less inform basic phenomena in the learning and teaching ofreading.

THE DEVELOPMENT OF PHONOLOGICAL AWARENESSACROSS LANGUAGES

The most important precursor skill for reading acquisitionacross languages is called phonological awareness. Phonologicalawareness first emerges as a natural part of languageacquisition. As children acquire language, they becomeaware of the sound patterning in their language, and usesimilarities and differences in sound patterning to organize themental lexicon (see Ziegler & Goswami, 2005). Phonologicalawareness is usually defined as the child’s ability to detectand manipulate component sounds in words. According tohierarchical theories of syllable structure, there are at leastthree linguistic levels at which component sounds can beconsidered. Children can be aware that (a) words can bebroken down into syllables (two syllables in wigwam, threesyllables in butterfly) and (b) syllables can be broken downinto onset-rime units (to divide a syllable into onset and rime,divide at the vowel, as in t-eam, dr-eam, str-eam. The term‘‘rime’’ is used because words with more than one syllable havemore than one rime, for example, in mountain and fountain,the rimes are ‘‘–ount’’ and ‘‘–ain’’, respectively. Finally, (c) thechild can become aware of phonemes.

Phonemes are the smallest speech sounds making up words,but phonemes are an abstract concept defined in terms ofsound substitutions that change meaning. For example, pinand pit differ in terms of their final phoneme, and pin andpan differ in terms of their medial phoneme. In all languagesstudied to date, phonemic awareness appears to emerge asa consequence of being taught to read and write. Prereadingchildren and illiterate adults are generally not aware ofphonemes: they perform poorly in tasks requiring themto manipulate or to detect single phonemes (e.g., Goswami& Bryant, 1990; Morais, Cary, Alegria, & Bertelson, 1979).Children who are learning to read become proficient indetecting and manipulating single phonemes fairly rapidly,and this proficiency depends on the age at which readingis taught and the transparency of the orthography that theyare learning (e.g., Seymour, Aro, & Erskine, 2003). Mattheweffects (the reciprocal effects of reading experience on othercognitive skills like phonological awareness) then compoundthese differences across languages (Stanovich, 1986). Themechanism for learning about phonemes seems to be learningabout letters. Letters are used to symbolize phonemes. Thissymbolic function requires child learners to focus on someof the phonological similarities they detect in the speechstream, and discard others. For example, words like TRAY andTRACK begin with the same sound as words like CHICKEN.However, we use different letters to represent this soundfor TRAY (the letters TR) versus CHICKEN (the letters CH).Beginning spellers who have not yet learned these orthographicconventions will represent the sounds with the same letter,as in the ‘‘invented spellings’’ ASCHRAY for ‘‘ashtray’’ and

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CHRIBLS for ‘‘troubles’’ (Read, 1986). One letter, such as P,can be used to symbolize physically quite different sounds(like the P in ‘‘pit’’ versus ‘‘spoon’’—young children may spellthe latter as SBN, and acoustically they are correct to do so).As children become expert readers and spellers, orthographiclearning changes phonological judgements, and possibly evenauditory processing (see Goswami, Ziegler, & Richardson,2005). Of course, such difficulties only arise for young learnersof orthographies that lack 1:1 letter-phoneme correspondence,like English. In most of the world’s alphabetic orthographies,the same letter always corresponds to the same sound (e.g.,Italian, Spanish, and Finnish).

The emergence of syllable and onset-rime awareness isdevelopmentally comparable across languages and appears tobe part of how the brain acquires language. Preschool childrenin all languages so far tested are aware of syllables, onsets,and rimes. The development of phonemic awareness varieswith language. Children learning transparent orthographieswith 1:1 correspondences between letters and phonemes,such as Greek, Finnish, German, and Italian, rapidly acquirephonemic awareness. Children who are learning to read inlanguages where morphology highlights phonetic contrasts,such as Turkish, also acquire phonemic awareness morerapidly (e.g., Durgunoglu, 2006; see also Frost, Katz, & Bentin,1987, for an explanation of the orthographic depth hypothesis).Children learning nontransparent orthographies like English,Danish, and French are slower to acquire phonemicawareness (see Ziegler & Goswami, 2005). Children learningnonalphabetic orthographies, like Chinese children, appearto acquire syllable, onset, and rime awareness in a mannersimilar to children who speak languages with alphabeticorthographies. The acquisition of phonemic awareness thenvaries dramatically as a function of whether the Chinesecharacters (Chinese does not use an alphabetic script) aretaught via early immersion in a phonetic script representingthe sounds of the characters (Pin-Yin in mainland China,Zhu-Yin-Fu-Hao in Taiwan) or are taught by rote. Childrenin mainland China and in Taiwan both acquire phonemicawareness (Huang & Hanley, 1995; Siok & Fletcher, 2001).Children in Hong Kong, who begin learning the Chinesecharacters by rote rather than via a phonetic script, donot appear to develop phonemic awareness (Huang &Hanley, 1995).

THE BASIC AUDITORY PROCESSES YIELDINGPHONOLOGICAL AWARENESS

To use the sound patterning of one’s language to organizethe mental lexicon, similarities and differences betweenthe sounds of words must be distinguished with relativeprecision. Basic auditory processing skills are the key to thisprecision. Recent research in child phonology suggests that

early phonological representations for words are essentially‘‘phonotactic templates’’ or ‘‘prosodic templates’’, namelyauditory patterns varying in intensity, duration, frequency,and rhythm (Pierrehumbert, 2003; Vihman & Croft, 2007).The dominant template in spoken English is bisyllabic, withstronger stress on the first syllable (e.g., ‘‘mummy’’, ‘‘daddy’’,‘‘baby’’). This prosodic template is so prevalent that we tendto alter the words that we use with babies to fit the pattern(‘‘milkie’’, ‘‘dolly’’, ‘‘doggie’’). It is also the first templatethat young children produce (e.g., ‘‘nana’’ for ‘‘banana’’). Todistinguish these prosodic templates in the stream of soundthat is spoken language, auditory cues to rhythm and stressare important.

A long time ago, it was proposed that basic auditoryprocessing difficulties might characterize both children withspecific language impairment (SLI), who have problemsin the basic acquisition of language, and children withdevelopmental dyslexia, who have problems in acquiringwritten but not in acquiring spoken language (Tallal & Piercy,1973, 1974; Tallal, 1980). Tallal’s focus on the importanceof the accurate perception of auditory temporal structurefor developing a phonological system was very insightful.However, she characterized the key temporal parametersfor phonological development as being rapidly changing ortransient acoustic events. This was presumably because in the1970s, it was believed that phonemes were the key to languagelearning, and that phonemes corresponded to acousticfeatures called formants—rapid changes in frequency andintensity (Blumstein & Stevens, 1981). Tallal (1980) arguedthat children with deficits in processing rapid and transienttemporal information would have consequent difficultiesin phoneme perception, and would thus have difficulty inacquiring literacy (as phoneme awareness was necessary forreading, see also Tallal, 2004).

In practice, however, rapid temporal information is onlynecessary for distinguishing between phonemes such as /b/or /d/ when they are heard without context. Speech soundsare seldom heard without context by young infants, and infact, the new template models of phonological developmentare not based on phonemes. They are based on prosodicpatterns that correspond to the speech envelope or amplitudeenvelope. Speech as an acoustic signal can be modeled byfactoring it mathematically into the product of a slowlyvarying envelope (also called amplitude modulation) and arapidly varying fine time structure (see Smith, Delgutte, &Oxenham, 2002). Experiments using ‘‘chimeric’’ sentencescreated from the envelope of one sentence and the finetime structure of another have shown that the brain reliesmainly on envelope cues for understanding speech (Smithet al., 2002). Babies who are deaf and who are given cochlearimplants that transmit only envelope information and norapid fine structure can develop language, and show thetypical hierarchical sequence (syllable, rhyme, phoneme)

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in developing phonological awareness (James et al., 2005).Clearly, basic auditory cues to the amplitude envelope, whichinclude the auditory cues that yield prosodic patterningand speech rhythm, must be important for phonologicaldevelopment (see also Foxton et al., 2003).

When mothers talk to their babies, they adopt a liltingrhythmic speech pattern called ‘‘Motherese’’. This is observedacross languages. Motherese (or infant-directed speech [IDS])is characterized in particular by higher pitch, greater pitch,and volume variability and the use of a small set of highlydistinctive melodic contours (e.g., Fernald et al., 1989). Theprosodic patterning provided by Motherese is thought tobe very important for infants acquiring language, who canuse speech rhythm and stress patterns as cues to potentialword boundaries (e.g., Cutler & Mehler, 1993; Echols, 1996).Infants show sensitivity to the speech rhythms characteristicof different languages very early indeed, at a few days old(e.g., Mehler et al., 1988). Rhythm is a complex acousticpercept. The auditory cues that yield rhythmic informationinclude the duration of sounds, their intensity (loudness), risetime (the rate of change of the amplitude modulation and thedepth of amplitude modulation), and changes in frequency(pitch changes). These auditory cues in combination in effectdescribe the amplitude envelope (see Figure 1). In recentresearch, we have been exploring the role of auditory cues suchas rise time and duration in the development of phonologicalawareness and literacy skills by children across languages.

RISE TIME, THE AMPLITUDE ENVELOPE, ANDPHONOLOGICAL AWARENESS

Rise time refers to the rate of change of the onset of theamplitude envelope of a particular auditory signal (speechor nonspeech). Rise time at syllable onset is thought to beparticularly important in the perception and production ofrhythmic speech (Bregman, 1993; Scott, 1998). As the maximalchange in amplitude as a syllable is produced coincides withthe production of the vowel, rise time is also a cue to vowel onset.The production of vowels in stressed syllables is accompaniedby particularly large amplitude changes and salient rise times,whereas unstressed syllables have smaller amplitude changesand smaller rise times. This can be seen in Figure 1. The sharprise time at the beginning of the first stressed syllable of‘‘quickly’’ is much stronger than at the beginning of the secondunstressed syllable, although both are associated with the samephoneme /k/. Rise time together with amplitude change is thusone auditory cue that is important for identifying the prosodictemplates that are integral to phonological development inEnglish, and rise time may also help with segmenting thesyllable into onset-rime units (t-eam, dr-eam, str-eam).

We have been studying rise time processing extensively inchildren with developmental dyslexia, as these children have

Fig. 1. Schematic representation of a speech utterance illustratinglocal changes in features such as duration (length of segments), pitch(black lines in bottom graph), intensity (dotted line in bottom graph),and rise and fall times (changes in the slope of the dotted line). Figurefrom Fosker, Huss, Szucs, and Goswami, 2008.

well-documented problems with phonological awareness,across languages. We have investigated whether childrenwith developmental dyslexia have particular problems indiscriminating rise time and other auditory cues related toamplitude envelope structure, such as duration and intensity.Children with developmental dyslexia are indeed significantlyless sensitive to rise time than typically developing children(Goswami et al., 2002; Richardson, Thomson, Scott, &Goswami, 2004; Thomson & Goswami, 2008; see Pasquini,Corriveau, & Goswami, 2007, for similar data with adults).Further, individual differences in rise time discriminationare predictive of phonological awareness, even when factorssuch as age, verbal and nonverbal IQ, and vocabulary arecontrolled. Precocious readers, who usually have exceptionalphonological skills, appear to be significantly more sensitiveto rise time than typically developing controls (Goswamiet al., 2002, study 2). This relative insensitivity to risetime in developmental dyslexia is also found for Frenchchildren (Muneaux, Ziegler, Truc, Thomson, & Goswami,2004) and for Hungarian children (Suranyi et al., 2009), andFinnish dyslexic children show a relationship between risetime perception and literacy development (Hamalainen et al.,2009). As French and Hungarian are syllable-timed languages,whereas English is a stress-timed language (i.e., the languagesrepresent different rhythm types), these findings suggestthat amplitude envelope cues are critical for phonologicaldevelopment at a level of auditory structure that is morebasic than rhythm type. Therefore, rise time discriminationis likely to play an important role in the development ofthe phonological system, and subsequently the acquisition ofliteracy, across languages.

EXPLORING AMPLITUDE ENVELOPE PERCEPTIONUSING NEUROSCIENCE METHODS

So far, the data suggest that (a) phonological develop-ment is important for reading acquisition across languages;



(b) phonological development prior to reading across lan-guages essentially comprises awareness of syllables, onsets,and rimes; (c) an important auditory cue to syllabic structure(and possibly the onset-rime division of the syllable) acrosslanguages is rise time; (d) phonological awareness is relatedto the basic auditory processing of cues like rise time; and(e) children with developmental dyslexia in a number of lan-guages have specific difficulties in discriminating rise time.Given that we appear to have identified a basic auditory cuethat contributes to phonological development and readingacquisition across languages, we can now explore the neuralcorrelates of rise time representation.

In my own research group, we have been exploringthe neural correlates of rise time processing using event-related potentials (ERPs). ERPs are particularly suitableneuroscience tools for questions about the development ofauditory processing skills, as auditory information comesin over time, and millisecond differences in the arrival ofinformation can have important consequences (e.g., for soundlocalization). ERPs enable the timing rather than localizationof neural events to be studied, and are time-locked to specificevents designed to study cognitive function. The most usualoutcome measures are (a) the latency of the potentials, (b) theamplitude (magnitude) of the various positive and negativechanges in neural response, and (c) the distribution of theactivity. The sequence of observed potentials and theiramplitude and duration are then used to understand theunderlying cognitive processes.

In our research, we have been focusing on the mismatchnegativity response (MMN). The MMN is a preattentivemeasure of the automatic detection of auditory change, and inadults there is a clear MMN to rise time (Thomson, Baldeweg,& Goswami, 2009). To date, however, we have had difficultyin finding a clear MMN to rise time in children aged from 7to 10 years. So far, we have suggestive data for the N100 andlate discriminative negativity (LDN) responses, but no cleardata for the MMN response. The N100 is an early auditorycomponent signifying the detection of auditory events. The LDNis a later component also related to sound discrimination (inparticular, to the detection of deviance in linguistic sounds,see Hommet et al., 2009). In a pilot study run by Thomson(2004), we asked children to listen to rise times of either15 ms (a very sharp or abrupt rise time) versus 90 ms (a moregradual rise time) through headphones as they watched asilent video. Behavioral data from other studies (Richardsonet al., 2004) had suggested that the difference between theserise times was usually perceived by control children but notby children with developmental dyslexia. Thomson (2004)found relatively clear patterns of N100 responding. For the15 ms rise time stimuli, both children with developmentaldyslexia and chronological age (CA) controls showed a largeN1 at the temporal (over temporal cortex) and mastoid(over temporal bone) electrode sites (approximately −2.5 μv).

For the 90 ms rise time stimuli, in contrast, the groupsdiverged. The CA controls showed a significantly reducedN1 amplitude for 90 ms rise times compared with 15 msrise times, whereas the dyslexic children did not. Henceneurally, the dyslexic brain was responding to the presence ofauditory events, as shown by the N1. However, the amplitudeof its response did not differentiate the relatively long risetime of 90 ms from the much shorter rise time of 15 ms.Yet this 75 ms difference in rise time is important for theaccurate perception of syllable onsets. The amplitude of theN100 was also significantly correlated with the behavioralmeasures. For example, behavioral performance on a risetime discrimination task was significantly correlated with N1amplitude (e.g., r = −0.77, temporal electrode LM, p < .01; anose reference was used), as were the phonological and literacymeasures (e.g., for electrode LM, learning novel phonologicalstrings, r = 0.68; performance on a standardized spellingtest, r = 0.74; performance on a phonological awarenesstask [oddity task], r = 0.80; p’s < .01). The data showedthat there was a relationship between the amplitude of theneural response to simple auditory rise time events and thechild’s behavior in tasks measuring literacy and phonologicalawareness.

In a more recent study seeking MMNs to rise time, Foskeret al. (2009) reported a difference in the LDN componentof the electroencephalographic (EEG) response to rise timechanges in children with developmental dyslexia compared toage-matched control children who were typically developingreaders. Using a paradigm based on Thomson (2004), in whichthe discrimination of tones with rise times of 15 ms wascompared to that of tones with rise times of 90 ms in apassive oddball paradigm, it was found that the children withdevelopmental dyslexia showed a significantly smaller LDNresponse to the rise time change. Behaviorally, the childrenwith developmental dyslexia were significantly impaired indiscriminating the rise times of simple tones, but not theirintensity. No difference in MMNs was found between the twogroups for either rise time or for intensity. Hence one possiblebiomarker for phonological difficulties and developmentaldyslexia could be rise time ERPs (N100 or LDN responses).However, whether the MMN will prove to be a useful ERPmarker for developmental dyslexia must be questioned (seealso Bishop, 2007, for a discussion of the inconsistent findingsfrom studies using MMNs to identify auditory processingdifficulties in SLI children).

Alternatively, it may be that devising a very accuratepsychoacoustic measure of rise time sensitivity, which wouldnot require brain imaging technology, could be a more usablebiomarker. This is suggested by data from another researchgroup, who have been examining the neural response to theamplitude envelope in typically developing children (Abrams,Nicol, Zecker, & Kraus, 2008). Kraus and her colleagues usedEEG in a different way to explore how well the brain of a child


Usha Goswami

could ‘‘phase lock’’ to the speech envelope. Their interest wasin whether the slower temporal features that characterize thespeech envelope would be processed preferentially by the righthemisphere. This is because studies using nonspeech acousticstimuli have shown that slower component rates (timescalescommensurate with processing syllabicity and intonationcontours) lateralize to the right hemisphere, whereas rapidcomponent rates (timescales commensurate with processingformant transitions) lateralize to the left hemisphere (Poeppel,2003). Abrams et al. used EEG to measure whether auditoryneurons would be activated in phase with the changes inacoustic energy that occur with the production of differentsyllables, that is as the amplitude envelope of speech risesand falls. In essence, they measured whether the child’s braincould track the speech envelope in real time, which theycalled ‘‘phase locking’’. In their paradigm, children listened tothousands of repetitions of someone saying ‘‘The young boyleft home’’ while EEG recordings were made. The waveform ofthe cortical response was compared to the stimulus waveformto see whether peaks in neural firing corresponded to risetimes in the speech envelope. The 12 children in the study(aged 9–13 years) tracked the speech envelope remarkablyaccurately, showing a series of positive peaks of neural activitywhich closely followed the temporal envelope of the speech,at least when right hemisphere responses were considered.In fact, the right hemisphere was 100% more accurate thanthe left in following the contours (rise times) of the speechenvelope.

This is a very promising technique for studying the causalmechanisms that underpin poor phonological development inchildren with developmental dyslexia. Given the psychoacous-tic rise time data discussed earlier, one plausible hypothesisis that the dyslexic brain is impaired at phase locking to therhythmic structure of the speech. A child with developmen-tal dyslexia would be expected to show an impaired righthemisphere contour- following response. If this were to be thecase, then we would have a plausible neural causal mecha-nism for impaired phonological development in developmentaldyslexia. If further studies showed that the accuracy of a child’scortical tracking of the speech envelope and their behavioralrise time thresholds were measuring the same underlying neu-ral weakness, then we would have a cognitive task that couldbe a useful biomarker for developmental dyslexia.

If the scenario that I outline were to be fulfilled, then theneuroscience paradigm developed by Kraus and her groupwill generate previously absent evidence with respect to thecausal mechanisms involved in developing good phonologicalawareness. The behavioral data outlined earlier support theutility of developing neural measures of amplitude envelopeprocessing, as the psychoacoustic studies pinpointed risetime as an important auditory parameter. Meanwhile, thecognitive studies highlighted the importance of prosodicand rhythmic structure for language acquisition and for

the development of the phonological system. Hence all thedifferent research paradigms were important in differentways. Both cognitive and educational studies of developmentaldyslexia identified phonological processing as the key factorin explaining individual differences in reading attainment, andsuggested that phonological awareness provided the optimalfocus for remediation. The psychoacoustic studies of rise timeprocessing showed that impaired rise time sensitivity seemsto be ubiquitous in developmental dyslexia, across languages.This in turn suggested that a more detailed neural investigationof how the brain tracks amplitude envelope onsets mightbe helpful in understanding phonological development. Themethod developed by Kraus and her colleagues yields apotentially more fruitful way of tackling this than measuringMMNs to rise time. This EEG paradigm also demonstrateda potential neural mechanism, phase locking to the speechenvelope, that may be atypical in the dyslexic brain. This nowoffers a way forward in terms of developing biomarkers fordevelopmental dyslexia.

If this hypothetical elucidation of developmental mecha-nisms is supported by future studies, the implications foreducation are clear. First, we would need to develop a simplelistening measure that taps rise time sensitivity in very youngchildren (see Corriveau, Thomson, & Goswami, in press, forone possibility). We might then decide to use EEG measures,such as phase locking to the speech envelope, to confirm cor-tical processing difficulties with speech in children with poorrise time sensitivity (see Molfese, 2000, for an alternative useof EEG based on syllables). And ideally, we would developuseful remediation and language enrichment programs thatcan target the deficiencies in rhythmic timing that appear tocharacterize the dyslexic brain. The rise time research suggeststhat preschool activities based around rhythm and language(including music and singing) could be particularly beneficial(see Goswami, in press).

CONCLUSIONS

Neural imaging of the brain’s responses to auditoryphenomena is an exciting avenue to explore with respect toproviding usable knowledge for education. As illustrated here,neuroscientific investigations of basic auditory processing canhelp us to understand the causal mechanisms underpinningthe development of phonological awareness, across languages.Having identified promising mechanisms, we need to carryout longitudinal studies, beginning in infancy, to track andunderstand developmental relationships between sensoryprocesses and cognitive outcomes like language acquisition.By deepening our understanding of brain responses to simpleauditory events, we can begin to develop biomarkers forlanguage difficulties and developmental dyslexia. Similarly,as our understanding of causal mechanisms improves, our



educational interventions and remedial teaching can also beimproved. Ideally, we will gain sufficient understanding toenable the creation of optimal learning environments for allchildren, whether they are at risk of a learning difficulty ornot. Obviously, while biomarkers can help in the identificationof learning difficulties such as developmental dyslexia, theoptimal learning environments for literacy will need to belanguage tailored.

Clearly, the research findings discussed here are onlya first step for a systematic program of neuroeducation.The rise time/speech envelope findings are insufficient atpresent to allow a ‘‘neuroscience-enriched’’ educator tomake any recommendations concerning the timing, sequence,differentiation, and methods of instruction in the earlyteaching of reading. However, such an educator couldargue that rhythm perception appears to have an importantconnection with phonological awareness across languages,and could suggest that an early focus on rhythm in preschool(e.g., playing a chime bar at different rhythmic rates to nurseryrhymes and jingles, learning to clap out syllables in wordsor to clap on stressed syllables, experience with percussionmatched to poetry or song, learning to recite poems with clearmetrical structure) might help to lay a solid foundation forliteracy. On the other hand, this could have been concludedwithout the neuroscience component of the research. What isadded by the neuroscience is a deeper understanding of causalmechanisms. The rise time data alone did not provide this. If thehypothesis that the dyslexic brain is inefficient in phase lockingto rhythmic information in speech is supported by furtherstudies, we can begin to think about how to facilitate children’sability to phase lock to any kind of rhythmic information. Forexample, rhythm is usually more overt in music than in speech.So perhaps the neuroscience-enriched educator would beginwith tapping or dancing in time with music.

As for the ‘‘pedagogically enriched’’ neuroscientist’sanswers to the educator’s questions about the ‘‘what’’ of brainresearch, the next steps are clear. We need neuroscientificinvestigation of the basic auditory parameters that contributeto the experience of rhythm and timing across languages (i.e.,rise time, duration, pitch, and intensity) and ideally acrossdifferent neurodevelopmental disorders. We need these inves-tigations to be longitudinal, either beginning in infancy or atleast commencing long before the child begins learning to read.The lowest level of impairment should be identified neurallyas early as possible, and developmental effects on higher-levelcognition examined in longitudinal studies (see Goswami,2003). This research strategy would not only provide insightsrelevant to improving the functioning of the impaired sys-tem, it would also reveal alternative developmental pathwaysto the same end state, enabling the identification of alter-native interventions (see Karmiloff-Smith & Thomas, 2003).Cross-syndrome comparisons could disentangle specific fromgeneral developmental effects, and would eventually enable

the effective design of robust biomarkers for specific disorderssuch as developmental dyslexia. Cross-language studies wouldestablish whether a single biomarker is relevant across lan-guages. We need to study all kinds of learners, however, notonly children with neurodevelopmental disorders. Childrenwhose literacy development is typical, children whose literacydevelopment is atypical, children for whom other aspects ofdevelopment are atypical although reading may be apparentlynormal (to rule out as well as rule in variables of interest), andadults who learn to read in later life, are all important. Herecross-sectional studies, particularly across languages, providea useful first step.

The new field of mind, brain, and education is an excitingone, with great future promise. In applying neuroscience toeducation, however, both ‘‘neuroscience-enriched’’ educatorsand ‘‘pedagogically-enriched’’ neuroscientists must proceedwith caution. We cannot afford to ignore the nature of whatis (and is not) possible to measure using current neurosciencetechniques when framing our research questions about thebrain. It is crucial to ‘‘start small’’, using the outcome measuresthat are actually possible given the current state of the art,and then to adapt educational questions to variables that wecan meaningfully measure. In the case of producing usableknowledge about literacy, I would argue that we need tobegin with auditory sensory processing. As illustrated here,even simple auditory stimuli such as tones varying in risetime have the potential to yield novel and helpful informationconcerning the development of the skills central to the learningand teaching of reading.

Acknowledgements—I thank Tim Fosker, Jarmo Hamalainen,and two anonymous referees for their helpful comments.Usha Goswami’s research is funded by the Medical ResearchCouncil, Ref. G0400574.

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mind, brain, and literacy: biomarkers as usable knowledge for education

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