Sex Differences in Sex Differences in the Neurocognition the Neurocognition

of Languageof LanguageMichael T. Ullman, Ivy V. Michael T. Ullman, Ivy V.

Estabrooke, Karsten Estabrooke, Karsten Steinhauer, Claudia BrovettoSteinhauer, Claudia Brovetto

Language ProcessingLanguage Processing

Language Processing depends on 2 Language Processing depends on 2 neurocognitive systemsneurocognitive systems Temporal-lobe based declarative memory systemTemporal-lobe based declarative memory system

Includes…Includes… Mental lexicon, which contains idiosyncratic word-specific Mental lexicon, which contains idiosyncratic word-specific

informationinformation E.g. for irregular past tense; break-brokeE.g. for irregular past tense; break-broke

Frontal/basal-ganglia procedural systemFrontal/basal-ganglia procedural system Includes…Includes…

Mental grammar underlying the real-time rule-based Mental grammar underlying the real-time rule-based composition of complex linguistic representationcomposition of complex linguistic representation

E.g. regular past tenses; play + edE.g. regular past tenses; play + ed Also used in motor skillsAlso used in motor skills

Females are better than males at Females are better than males at remembering wordsremembering words Females tend to memorize previously Females tend to memorize previously

encountered complex representationsencountered complex representations E.g. regular past-tenses; playedE.g. regular past-tenses; played

Males generally compose it on-lineMales generally compose it on-line E.g. play + -edE.g. play + -ed

Prediction…Prediction…

Both sexes should memorize Both sexes should memorize idiosyncratic lexical knowledge idiosyncratic lexical knowledge E.g. break-brokeE.g. break-broke

Both should rule compute new Both should rule compute new complex formscomplex forms E.g. proy-edE.g. proy-ed

Why?Why? Because these could not be memorizedBecause these could not be memorized

Previous studiesPrevious studies Frequency EffectsFrequency Effects

Hypothesis: if past-tense representations are Hypothesis: if past-tense representations are retrieved from memory, more frequent ones should retrieved from memory, more frequent ones should be remembered faster. If they are rule products, be remembered faster. If they are rule products, such past-tense frequency effects are not expectedsuch past-tense frequency effects are not expected

16 men and 17 women produced regular/irregular past 16 men and 17 women produced regular/irregular past tensestenses

DV: reaction-timeDV: reaction-time Men showed past tense frequency effects for irregulars but Men showed past tense frequency effects for irregulars but

not regularsnot regulars Women showed past tense frequency effects for both verb Women showed past tense frequency effects for both verb

typestypes

Same results for both English and Spanish Same results for both English and Spanish

Parkinson’s DiseaseParkinson’s Disease Associated with the Basal-ganglia degeneration Associated with the Basal-ganglia degeneration

leading to hypokinesia (suppressed movement)leading to hypokinesia (suppressed movement) Study: 15 men and 14 women with Parkinson’s Study: 15 men and 14 women with Parkinson’s

disease produced past tensesdisease produced past tenses For men, past-tense production rates of regulars but not For men, past-tense production rates of regulars but not

irregulars correlated with hypokinesia and production irregulars correlated with hypokinesia and production rates for irregulars but not regulars correlated with rates for irregulars but not regulars correlated with lexical abilities (object naming)lexical abilities (object naming)

For women, production rate for both past-tense types For women, production rate for both past-tense types correlated with lexical abilities but not hypokinesiacorrelated with lexical abilities but not hypokinesia

Most hypokinetic males were impaired only at Most hypokinetic males were impaired only at regularsregulars

Most hypokinetic women were impaired at neitherMost hypokinetic women were impaired at neither

The Effect of Sex Hormones The Effect of Sex Hormones on Language Processingon Language Processing

Ivy V. Estabrooke, Kristen Mordecai, Pauline Maki, and Ivy V. Estabrooke, Kristen Mordecai, Pauline Maki, and Michale T. UllmanMichale T. Ullman

As stated before, women are better As stated before, women are better than men at remembering wordsthan men at remembering words This advantage appears to depend upon the This advantage appears to depend upon the

temporal-lobe declarative memory systemtemporal-lobe declarative memory system Hypothesis: Because of women’s Hypothesis: Because of women’s

superior lexical/declarative memory superior lexical/declarative memory ability, girls and women may tend to ability, girls and women may tend to memorize and/or retrieve at least memorize and/or retrieve at least certain complex representations that certain complex representations that men composed on-linemen composed on-line

From this, two questions ariseFrom this, two questions arise 1. Do females memorize complex forms at a 1. Do females memorize complex forms at a

higher rate than males and/or do both sexes store higher rate than males and/or do both sexes store tense forms, while females have superior lexical tense forms, while females have superior lexical retrieval/processing abilitiesretrieval/processing abilities

2. Do sex hormones, and estrogen in particular, 2. Do sex hormones, and estrogen in particular, contribute to the sex differences?contribute to the sex differences?

Previous data supports this hypothesisPrevious data supports this hypothesis Estrogen improves word and declarative memory abilities Estrogen improves word and declarative memory abilities

in women; more over, this improvement depends on the in women; more over, this improvement depends on the part of the temporal lobe that underlies declarative part of the temporal lobe that underlies declarative memorymemory

Furthermore, testosterone improves men’s word Furthermore, testosterone improves men’s word memorymemory

MethodsMethods 10 post-menopausal women and 12 age-matched 10 post-menopausal women and 12 age-matched

men participate in study of the effects of men participate in study of the effects of hormone therapy on language processinghormone therapy on language processing Subjects were given hormone replacement therapySubjects were given hormone replacement therapy

Women-estrogen, Men-testosterone, and placebo groupWomen-estrogen, Men-testosterone, and placebo group After each three months, subjects were given past-After each three months, subjects were given past-

tense production task containing…tense production task containing… Regular (sway-swayed) , irregular (break-broke), novel Regular (sway-swayed) , irregular (break-broke), novel

regular (plag-plagged) and novel irregular (spling-splung)regular (plag-plagged) and novel irregular (spling-splung) Verbs were presented in sentence contextsVerbs were presented in sentence contexts

E.g. Every day I sleep in bed. Yesterday, I ________ in bed.E.g. Every day I sleep in bed. Yesterday, I ________ in bed. Accuracy was the DVAccuracy was the DV

ResultsResults Hormone therapy yielded increased estrogen Hormone therapy yielded increased estrogen

levels in both sexeslevels in both sexes It also induced an increase in both sexes in the It also induced an increase in both sexes in the

production rate of real and novel irregular past production rate of real and novel irregular past tensestenses

Performance at novel regulars decreased with Performance at novel regulars decreased with hormone therapy in both sexeshormone therapy in both sexes Likely due to an increased irregularizations (plag-plog)Likely due to an increased irregularizations (plag-plog)

Accuracy at real regulars INCREASED in women Accuracy at real regulars INCREASED in women but DECREASED in men, as a result of hormone but DECREASED in men, as a result of hormone therapytherapy

Accuracy at Past Tense Accuracy at Past Tense ProductionProduction

AnalysisAnalysis

Increase in both women and men in Increase in both women and men in production rate of real/novel irregular production rate of real/novel irregular past-tense forms suggests that sex past-tense forms suggests that sex hormones improve the hormones improve the retrieval/processing of existing retrieval/processing of existing memorized lexical representations memorized lexical representations

And of novel forms whose processing And of novel forms whose processing depends on preexisting similar memory depends on preexisting similar memory tracestraces E.g. fling-flung, wring-wrungE.g. fling-flung, wring-wrung

The decrease in performance of The decrease in performance of novel regulars with hormone therapy novel regulars with hormone therapy in both sexes..in both sexes.. Supports view that these forms are Supports view that these forms are

computed by neural mechanisms computed by neural mechanisms distinct from those that underlie the distinct from those that underlie the processing of real and novel irregularsprocessing of real and novel irregulars

It also supports the dual-system It also supports the dual-system “declarative/procedural model”“declarative/procedural model”

The fact that hormone therapy led to The fact that hormone therapy led to an increase in the production rate of an increase in the production rate of regular past-tenses in women, but a regular past-tenses in women, but a decrease in men shows that in decrease in men shows that in women these forms patttern with the women these forms patttern with the mempry-dependent irregulars and in mempry-dependent irregulars and in men, they pattern with the men, they pattern with the compositional novel regularscompositional novel regulars

ConclusionConclusion

The sex differences just observed The sex differences just observed may be attributable to the prior may be attributable to the prior memorization of complex forms by memorization of complex forms by girlsgirls

This may be explained by sex-This may be explained by sex-differences in estrogen levels, which differences in estrogen levels, which could affect brain organization in could affect brain organization in utero and or learning during utero and or learning during childhoodchildhood