Bilingualism and Cognitive Processing

Tamar H. Gollan, Ph.D., Professor 
Department of Psychiatry
University of California, San Diego

9500 Gilman Drive
La Jolla, CA 92093-0948
phone: (858) 246-1263
fax: (858) 246-1287
email: tgollan AT ucsd DOT edu


Welcome to the laboratory of research on Bilingualism, Aging & Alzheimer's disease. Going left to right in the photo above that's me (Tamar Gollan), Dorit Segal, Alena Stasenko, Rosa Montoya, Chuchu Li, Reina Mizrahi, Lesley Guarena-Espinosa, Mayra Murillo,  Julie Fadlon, and Tiffany Ho. Of course we all speak English, but together we also have at least 3 Hebrew speakers, 2 Russian speakers, at least 5 Spanish speakers, and 2 Mandarin speakers.  

People who speak more than one language seem to do so effortlessly. But things aren't always what they seem. By considering how the cognitive system juggles languages, bilinguals can provide a unique experimental tool for viewing language processing mechanisms, and how they work in concert with general cognitive mechanisms to rapidly produce error free speech.

Research in the lab is funded by the National Institute of Health (
NIDCD) and the National Science Foundation (NSF).

Young participants are tested primarily on the UCSD campus in the Language Production Lab (photo below). We have been holding weekly lab meetings together with Vic Ferreria's lab for over 10 years now. Our healthy aging bilinguals,
and our bilinguals with Alzheimer's disease, come mostly from a longitudinal study based at the UCSD Alzheimer's Disease Center

  Bilinguals enjoy many advantages. Most importantly they can communicate with a broader audience, and have diverse cultural experiences. However, bilinguals need to learn and efficiently retrieve about twice as many words as monolinguals. Such learning takes time, and it would be very surprising if this doubled load didn't produce any differences between bilinguals and monolinguals. Indeed we have found that, when compared with monolinguals, bilinguals name pictures more slowly (by about 80 milliseconds; Gollan, Montoya, Fennema- Notestine, & Morris, 2005), and can produce fewer  words in category generation (especially semantic categories such as Animal namesGollan, Montoya, & Werner, 2002). Additionally, bilinguals are more likely to have a tip-of-the-tongue or TOT state (Gollan & Silverberg, 2001), and are more likely to produce tongue twister errors (Gollan & Goldrick, 2012)

   In other testing conditions we find no differences between bilinguals and monolinguals. For example, bilinguals have the same number of TOTs as monolinguals when trying to retrieve words that are similar across languages (e.g., trompeta which is the Spanish word for trumpet; Gollan & Acenas, 2004), or when retrieving proper names which are also similar across languages (e.g., Tamar is Tamar in both Hebrew and in English;
Gollan, Bonanni, & Montoya, 2005). The appearance of a bilingual disadvantage in some but not in other tasks helps us to understand what sorts of processing is required to complete these tasks, and constrains models of bilingualism, language processing, and cognitive control.
Most people assume bilinguals might be different from monolinguals because of interference between languages. But my favorite explanation for bilingual disadvantages is simply that bilinguals spend less time using words particular to each language relative to monolinguals (because bilinguals use each language only some of the time whereas monolinguals use the same language all the time). On this view,  performance differences should be attributed to  reduced-use or a "frequency lag" (Gollan, Montoya, Cera, & Sandoval, 2008; Gollan, Slattery, Goldenberg, Van Assche, Duyck, & Rayner, 2011). Although I agree that both languages are always active, my research questions the simple idea that all of the consequences of bilingualism should be attributed to competition or interference between language systems. Bilinguals differ from monolinguals in many ways; it would be too simplistic to try to explain all of those differences with just one cognitive mechanism. An important point is that frequency-lag and interference are not mutually exclusive accounts - both are likely to be right. When viewed in this way, the goal of our research is to discover all the cognitive mechanisms that produce differences between bilinguals and monolinguals, to determine which mechanism best explains each effect we observe, and to figure out what these effects tell us about the cognitive system and language processing more generally.

    In recent work we are finding evidence for a link between language control and non-linguistic task control (e.g., switching declines in aging in related ways across linguistic and non-linguistic tasks; Weissberger, Wierenga, Bondi, & Gollan, 2012; see also Prior & Gollan, 2011). However, we also observe some profound limitations on the extent to which language control is related to general abilities. Bilinguals - even older bilinguals - almost never produce the wrong language by mistake (only 0-3% of the time; Gollan, Salmon, & Sandoval, 2011).  In addition, some age related "deficits" reflect the burden of responding to laboratory task demands. When aging bilinguals are allowed to voluntarily choose which language to use to name pictures, aging-related switching difficulties largely vanish and old bilinguals choose to switch as often as young bilinguals
(Gollan & Ferreira, 2009). We have even found that bilinguals with Alzheimer's disease maintain surprisingly good ability to access names in a non-dominant language (Gollan, Salmon, Montoya, & da Pena, 2010).  We have also found that older bilinguals are in some ways "better bilinguals" than young bilinguals (e.g., they retrieve low frequency words in their non-dominant language relatively more easily than would be expected given their ability to retrieve higher frequency words; Gollan, et al., 2008). The frequency-lag account provides a ready explanation for this finding; older bilinguals have had more time than young bilinguals in which to learn and efficiently retrieve twice as many words.

The best part about studying bilinguals is that by trying to figure out how bilinguals juggle their languages, and how they are different from monolinguals, we get to find out about all kinds of things such as why people get stuck in tip-of-the-tongue state states, why they make speech errors,  how we choose among competing responses when we speak, how word-frequency is represented in the lexicon, what makes for efficient switching between tasks (to find out how you can switch languages for free, see Kleinman & Gollan, in press), and how aging and Alzheimer's disease affect access to the language system. Our studies reveal some specialized language processing mechanisms, and a small role for  non-linguistic cognitive control in allowing bilinguals to maintain control over which language is selected. In more simple terms, this means that bilinguals are not constantly faced with a difficult selection problem - interference effects are limited - and frequency of use has powerful effects on proficiency and access to the two language systems.


Many cognitive assessment tests rely on language and were not designed for use with bilinguals. We have begun developing a Multilingual Naming Test (MINT) which we hope will be useful for test speakers of English, Spanish, Mandarin Chinese, Hebrew, and people who speak any combination of these languages. As a first step in developing this test we have found that it works equally well for classifying young and older Spanish-English bilinguals in terms of language dominance, and provides a closer match between proficiency interviews and naming test scores than existing naming tests (e.g., the Boston Naming Test, or BNT). Recently, we also demonstrated that the MINT detects naming impairments in monolinguals with Alzheimer's disease - which means the MINT might ultimately prove to be useful for testing both bilinguals and monolinguals (Ivanova, Salmon, & Gollan, 2013). In April of 2015, all the ADRCs across the country began using the MINT instead of the BNT in their annual evaluations.

The lack of tools available for cognitive assessment of bilinguals puts them at risk for being diagnosed with an impairment where none is present.
To make matters even more complex, cognitively intact bilinguals sometimes produce an "Alzheimer's-like pattern" on some tests. For example, the bilingual fluency disadvantage is greater on semantic than on letter category fluency (see Gollan, Montoya, & Werner, 2002), and bilinguals name fewer pictures correctly on the Boston Naming Test (see Gollan, Fennema-Notestine, Montoya, & Jernigan, 2007). Interestingly, some language based measures do not reveal a bilingual disadvantage, and some tests that do not seem to require language do reveal a bilingual disadvantage. For example, preliminary results suggest that bilinguals perform as well as monolinguals on the CVLT-II (California Verbal Learning Test-II) which is a very difficult test in which people try to remember a list of 16 words. Currently, we are trying to determine the best way to test bilinguals for the purpose of identifying cognitive impairment in its earliest stages. In bilingual Alzheimer's disease (AD) we are finding that the dominant language is most sensitive to differences between patients and controls (Gollan, et al, 2010). Most recently, we found that bilinguals with AD produce more intrusion errors than healthy aging bilingual controls when reading aloud mixed-language paragraphs, especially when they read paragraphs written mostly in their non-dominant language with a small number of dominant language words (Gollan, Stasenko, Li, & Salmon, 2017).   


I am a cognitive neuropsychologist, and a Hebrew-English-Spanish trilingual. I was an undergraduate at Brandeis University where I studied with Art Wingfield. Before graduate school I was a research assisstant at Massachusetts General Hospital with Scott Sokol. I got my Ph.D. in clinical and cognitive psychology from the Univeristy of Arizona or UofA where I worked with Merrill Garrett and Ken Forster. I also worked with visiting professor Ram Frost and then did a post-doc with Debby Burke at Pomona college. My first NIH grant was a K23 (a mentored Career Development Award with  Judy F. Kroll as a mentor). These days I continue to learn new things from many collaborators and from folks in my own lab.

None of the research I do would get done without hard working lab members (who are shown above), and support from my family (a recent photo here). 


Gollan, T.H., & Goldrick, M. (2017). A switch is not a switch: Syntactically driven bilingual language control. Journal of Experimental Psychology: Learning, Memory, & Cognition

Stasenko, A., Matt, G.E., & Gollan, T.H. (2017). A relative bilingual advantage in switching with preparation: Nuanced explorations of the proposed association between bilingualism and task switching. Journal of Experimental Psychology: General

Gollan, T. H., Stasenko, A., Li, C., & Salmon, D.P. (2017). Bilingual language intrusions and other speech errors in Alzheimer’s disease. Brain & Cognition, 118, 27-44.

Li, C., Goldrick, M., & Gollan, T.H (2017). Bilinguals’ Twisted Tongues: Frequency Lag or Interference? Memory & Cognition, 45, 600-610.

Ivanova, I., Ferreira, V.S., & Gollan, T.H (2017). Form overrides meaning when bilinguals monitor for errors. Journal of Memory and Language, 94, 75-102.

Gollan, T.H., & Goldrick, M. (2016). Grammatical constraints on language switching: Language control is not just executive control. Journal of Memory and Language, 90, 177-199.

Kleinman, D., & Gollan, T. H. (2016). Speaking two languages for the price of one: Bypassing language control mechanisms via accessibility-driven switches. Psychological Science, 27, 700-714.

Van Assche, E., Duyck, W., & Gollan, T.H. (2016) Linking comprehension and production: Cross-modal transfer effects between picture naming and lexical decision during first and second language processing in bilinguals. Journal of Memory and Language89, 37-54.

Ivanova, I., Murillo, M., Montoya, R.I., & Gollan, T.H. (2016). Does language control decline in older age? Linguistic Approaches to Bilingualism, 6, 86-118.

Emmorey, K., Giezen, M.R., & Gollan, T.H. (2016). Insights from bimodal bilingualism: Reply to commentaries. Bilingualism: Language and Cognition, 19(2), 261–263.

Emmorey, K., Giezen, M.R., & Gollan, T.H. (2016). Psycholinguistic, cognitive and neural implications of bimodal bilingualism. Bilingualism: Language and Cognition, 19(2), 223–242.

Gollan, T.H., Starr, J., Ferreira, V.S. (2015). More than Use it or Lose it: The number of speakers effect on Heritage Language Proficiency, Psychonomic Bulletin & Review, 22, 147-155.

Weissberger, G.H., Gollan, T.H., Bondi, M.W., Clark, L.R., Wierenga, C.E. (2015). Language and Task Switching in the Bilingual Brain: Bilinguals are Staying, not Switching, Experts. Neuropsychologia, 66, 193-203.

Tao, L, Taft, M. &  Gollan, T.H.,  (2015). The bilingual switching advantage: Sometimes related to bilingual proficiency, sometimes not. The Journal of the International Neuropsychological Society, 21, 531-544.

Gollan, T. H., Kleinman, D., & Wierenga, C. E. (2014). What's easier: Doing what you want, or being told what to do? Cued versus voluntary language and task switching. Journal of Experimental Psychology: General, 143, 2167-2195.

Sheng, L., Lu, Y., & Gollan, T.H., (2014). Assessing language dominance in Mandarin-English bilinguals: Convergence and divergence between subjective and objective measures. Bilingualism: Language and Cognition, 17, 364-383.

Kroll, J. F., & Gollan, T. H. (2014). Speech planning in two languages: What bilinguals tell us about language production. In V. Ferreira, M. Goldrick, & M. Miozzo (Eds.). The Oxford handbook of language production (pp. 165-181). Oxford: Oxford University Press.

Gollan, T.H., Schotter, E.R., Gomez, J., Murillo, M., Rayner, K. (2014). Multiple levels of bilingual language control: Evidence from language intrusions in reading aloud. Psychological Science, 25, 585-595.

Ivanova, I., Salmon, D.P., Gollan, T.H. (2014). Which language declines more? Longitudinal versus cross-sectional decline of picture naming in bilinguals with Alzheimer’s disease. The Journal of the International Neuropsychological Society, 20, 534-546.

Wardlow, L., Ivanova, I., & Gollan, T.H. (2014). The cognitive mechanisms underlying perspective taking between conversational partners: evidence from speakers with Alzheimer׳s disease. Neuropsychologia, 56, 184-195.

Gollan, T.H., Ferreira, V.S., Cera, C., Flett, S. (2014). Translation-priming effects of tip-of-the-tongue states. Language and Cognitive Processes, 29, 278-288. DOI:10.1080/01690965.2012.762457.

Suarez, P., Gollan, T.H., Heaton, R., Grant, I., Cherner, M., (2014). Second-language fluency predicts native language Stroop effects: Evidence from Spanish-English bilinguals The Journal of the International Neuropsychological Society, 20, 342-348.

Runnquist, E., Gollan, T. H., Costa, A., & Ferreira, V. S.  (2013).  A disadvantage in bilingual sentence production modulated by syntactic frequency and similarity across languages.  Cognition, 129, 256-263.

Van Assche, E., Duyck, W., & Gollan, T.H., (2013). Whole-language and item-specific control in bilingual language production, Journal of Experimental Psychology: Learning, Memory, & Cognition, 39, 1781-1792.

Prior, A., & Gollan, T.H., (2013). The elusive link between language control and executive control: A case of limited transfer, The Journal of Cognitive Psychology, 25, 622-645.

Kang, S.H.K., Gollan, T.H., & Pashler, H. (2013). Don’t just repeat after me: Retrieval practice is better than imitation for foreign vocabulary learning. Psychonomic Bulletin & Review, 20, 1259-1265.

Weissberger, G. H., Salmon, D. P., Bondi., M. W., Gollan, T. H. (2013). Which            neuropsychological tests predict progression to Alzheimer’s disease in Hispanics? Neuropsychology, 27, 343-355.

Ivanova, I., Salmon, D.P., & Gollan, T.H., (2013). The Multilingual Naming Test in Alzheimer’s disease: Clues to the origin of naming impairments. The Journal of the International Neuropsychological Society, 19, 272-283.

Emmorey, K., Petrich, J., & Gollan, T.H., (2013). Bimodal bilingualism and the frequency-lag hypothesis. Journal of Deaf Studies and Deaf Education, 18, 1-11.

Gollan, T.H. & Goldrick, M. (2012). Does bilingualism twist your tongue? Cognition, 125, 491-497.

Weissberger, G. H., Wierenga, C. E., Bondi, M. W., & Gollan, T. H. (2012). Partially over-lapping mechanisms of language and task control in young and older bilinguals. Psychology and Aging, 27, 959-974.

Emmorey, K., Petrich, J., & Gollan, T.H., (2012). Bilingual processing of ASL-English code-blends: The consequences of accessing two lexical representations simultaneously. Journal of Memory and Language, 67, 199-210.

Antón-Méndez, I., Schütze, C.T., Champion, M.K., & Gollan, T.H. (2012). What the tip-of-the-tongue (TOT) says about homophone frequency inheritance. Memory & Cognition, 40, 802-811.

Gollan, T.H.,  Weissberger, G., Runnqvist, E., Montoya, R.I., & Cera, C.M. (2012) Self-ratings of spoken language dominance: A multi-lingual naming test (MINT) and preliminary norms for young and aging Spanish-English bilinguals. Bilingualism: Language and Cognition, 15, 594-615.

Kamat, R., Ghate, M., Gollan, T.H., Meyer, R., Vaida, F., Heaton, R.K., Letendre, S., Franklin, D., Alexander, T., Grant, I., Mehendale, S., Marcotte, T.D., and the HIV Neurobehavioral Research Program (HNRP) Group (2012). Effects of Marathi-Hindi Bilingualism on Neuropsychological Performance. Journal of the International Neuropsychological Society, 18, 305-313.

Gollan, T.H., Sandoval, T., & Salmon, D.P. (2011). Cross-language intrusion errors in aging bilinguals reveal the link between executive control and language selection Psychological Science, 22, 1155-1164.

Gollan, T.H., Slattery, T.J., Goldenberg, D., van Assche, E., Duyck, W., & Rayner, K. (2011). Frequency drives lexical access in reading but not in speaking: The frequency-lag hypothesis. Journal of Experimental Psychology: General, 140, 186-209.

Gollan, T.H., Salmon, D.P., Montoya, R.I., & Galasko, D.R. (2011). Degree of Bilingualism Predicts Age of Diagnosis of Alzheimer’s Disease in Low-Education but not in Highly-Educated Hispanics, Neuropsychologia, 49, 3826-3830.

Prior, A. & Gollan, T.H. (2011). Good language-switchers are good task-switchers: Evidence from Spanish-English and Mandarin-English bilinguals. The Journal of the International Neuropsychological Society, 17, 682-691.

Gollan, T.H., Salmon, D.P., Montoya, R.I., Da Pena, E. (2010). Accessibility of the nondominant language in picture naming: A counterintuitive effect of dementia on bilingual language production. Neuropsychologia, 48, 1356-1366.

Antón-Méndez, I. & Gollan, T.H. (2010). Not just semantics: Strong frequency and weak cognate effects on semantic association in bilinguals. Memory and Cognition, 38, 723-739.

Sandoval, T.C., Gollan, T.H., Ferreira, V.S., & Salmon, D.P. (2010). What causes the bilingual disadvantage in verbal fluency: The dual-task analogy. Bilingualism: Language and Cognition, 13, 231-252.

Bialystok, E., Craik, F.I.M., Green, D.W., & Gollan, T.H. (2009). Bilingual minds. Psychological Science in the Public Interest, 10, 89-129.

Gollan, T.H., & Ferreira, V.S., (2009).  Should I stay or should I switch? A cost-benefit analysis of voluntary language switching in young and aging bilinguals. Journal of Expermental Psychology: Learning, Memory, & Cognition, 35, 640-665.

Pyers, J., Gollan, T.H., & Emmorey, K. (2009). Bimodal bilinguals reveal the source of tip-of-the-tongue states. Cognition, 112, 323-329.

Rivera Mindt, M., Arentoft, A., Kubo Germano, K., D'Aquila, E., Scheiner, D., Pizzirusso, M., Sandoval, T.C., & Gollan, T.H. (2008). Neuropsychological, cognitive, and theoretical considerations for evaluation of bilingual individuals.  Neuropsychology Review, 18, 255-268.

Gollan, T.H., Montoya, R.I., Cera, C.M., & & Sandoval, T.C., (2008). More use almost always means smaller a frequency effect: Aging, bilingualism, and the weaker links hypothesis. Journal of Memory and Language, 58, 787-814.

Emmorey, K., Borinstein, H. B. & Thompson, R., & Gollan, T.H. (2008).  Bimodal bilingualism.  Bilingualism:  Language and Cognition, 11, 43-61.

Gollan, T.H., Fennema-Notestine, C., (2007). What is it about bilingualism that affects BNT performance? A reply to commentaries. The Journal of the International Neuropsychological Society, 13, 215-218.

Gollan, T.H., Fennema-Notestine, C., Montoya, R.I., & Jernigan, T.L. (2007). The Bilingual Effect on Boston Naming Test performance. The Journal of the International Neuropsychological Society, 13, 197-208.

Gollan, T.H., Salmon, D.P., Paxton, J.L. (2006). Word association in early Alzheimer's Disease. Brain and Language, 99, 289-303.

Gollan, T.H., & Brown, A.S. (2006). From tip-of-the-tongue (TOT) data to theoretical implications in two steps: When more TOTs means better retrieval. Journal of Experimental Psychology: General, 135, 462-483.

Finkbeiner, M., Gollan, T.H., & Caramazza, A. (2006). Lexical access in bilingual speakers: What’s the (hard) problem? Bilingualism: Language and Cognition, 9, 153-166.

Michael, E., & Gollan, T.H. (2005). Being and becoming bilingual: Individual Differences and consequences for language production. In J.F. Kroll & A.M.B. de Groot (Eds.), The handbook of bilingualism: Psycholinguistic approaches (pp. 389-407). NY: Oxford University Press.

Thompson, R., Emmorey, K., Gollan, T.H. (2005).  “Tip of the fingers” experiences by deaf signers: Insights into the organization of sign-based lexicon. Psychological Science, 16, 856-860.

Gollan, T.H., Montoya, R.I., Fennema-Notestine, C., Morris, S.K., (2005). Bilingualism affects picture naming but not picture classification. Memory & Cognition, 33, 1220-1234.

Gollan, T.H., Bonanni, M.P., & Montoya, R.I. (2005). Proper names get stuck on bilingual and monolingual speakers tip-of-the-tongue equally often. Neuropsychology, 19, 278-287

Gollan, T.H. & Acenas, L.A. (2004). What is a TOT?: Cognate and translation effects on tip-of-the-tongue states in Spanish-English and Tagalog-English bilinguals. Journal of Experimental Psychology: Learning, Memory, & Cognition, 30, 246-269.

Morris, S.K., Fennema-Notestine, Gollan, T.H., & Jernigan, T.L., (2003). Hispanic Bilinguals & English Monolinguals Show BOLD Activation Differences on an fMRI Picture Classification Paradigm. Neuroimage, 19, 1331.

Gollan, T.H., Montoya, R.I., Werner, G.A. (2002). Semantic and letter fluency in Spanish-English bilinguals. Neuropsychology, 16, 562-576.

Gollan, T., & Kroll, J. F. (2001). Bilingual lexical access. In B. Rapp (Ed.), The handbook of cognitive neuropsychology: What deficits reveal about the human mind (pp. 321-345). Philadelphia, PA: Psychology Press.

Gollan, T.H. & Frost, R. (2001).  Two Routes to Grammatical Gender: Evidence from Hebrew. Journal of Psycholinguistic Research, 30, 627-651.

Gollan, T.H. & Silverberg, N.B. (2001) Tip-of-the-tongue states in Hebrew-English bilinguals. Bilingualism: Language and Cognition, 4, 63-83.

Gollan, T.H., Forster, K.I., & Frost, R. (1997).  Translation priming with different scripts: Masked priming with cognates and non-cognates in Hebrew-English bilinguals. Journal of Experimental Psychology: Learning, Memory, & Cognition, 23, 1122-1139.

Gollan, T.H., Forster, K.I., & Frost, R. (1995).  Asymmetrical access to bilingual lexical representations. Brain & Language, 51, 134-137.

Sokol, S.M., Macaruso, P., & Gollan, T.H. (1994).  Developmental dyscalculia and cognitive neuropsychology.  Developmental Neuropsychology, 10, 413-441. 

this web-page last updated in September, 2017