Skip to main content


  • Jens Schmidtke (a1)

It has been known since at least the 1960s that small changes in pupil diameter in response to a mental task are indicative of processing effort associated with this task. More recently, with the advent of modern eye-trackers, which also measure the pupil diameter, pupillometry has been “rediscovered” by language researchers and the method has since been used in many different subdisciplines of linguistics. This article gives a nonexhaustive overview about recent linguistic research with the purpose of introducing researchers in the field of second language acquisition (SLA) to pupillometry. In addition, the article discusses things to consider when designing an experiment and how pupil data can be analyzed. The range of possibilities in which pupillometry can be used in experimental SLA research makes it a welcome addition to other online methods such as eye-tracking and event-related potentials.

Corresponding author
*Correspondence concerning this article should be addressed to Jens Schmidtke, P.O. Box 35247, Amman 11180, Jordan. E-mail:
Hide All
Aston-Jones, G., & Cohen, J. D. (2005). An integrative theory of locus coeruleus-norepinephrine function: Adaptive gain and optimal performance. Annual Review of Neuroscience, 28, 403–50. doi: 10.1146/annurev.neuro.28.061604.135709
Aston-Jones, G., Rajkowski, J., & Cohen, J. (1999). Role of locus coeruleus in attention and behavioral flexibility. Biological Psychiatry, 46, 13091320. doi: 10.1016/S0006-3223(99)00140-7
Beatty, J. (1982). Task-evoked pupillary responses, processing load, and the structure of processing resources. Psychological Bulletin, 91, 276292.
Beatty, J., & Lucero-Wagoner, B. (2000). The pupillary system. In Cacioppo, J. T., Tassinary, L. G., & Berntson, G. G. (Eds.), Handbook of psychophysiology (2nd ed., pp. 142162). Cambridge, UK: Cambridge University Press.
Ben-Nun, Y. (1986). The use of pupillometry in the study of on-line verbal processing: Evidence for depths of processing. Brain and Language, 28, 111.
Bradlow, A. R., & Pisoni, D. B. (1999). Recognition of spoken words by native and non-native listeners: Talker-, listener-, and item-related factors. Journal of the Acoustical Society of America, 106, 20742085. doi: 10.1121/1.427952
Bradshaw, J. L. (1969). Background light intensity and pupillary response in a reaction time task. Psychonomic Science, 14, 271272.
Brisson, J., Mainville, M., Mailloux, D., Beaulieu, C., Serres, J., & Sirois, S. (2013). Pupil diameter measurement errors as a function of gaze direction in corneal reflection eyetrackers. Behavior Research Methods, 45, 13221331. doi: 10.3758/s13428-013-0327-0
Chapman, C., Oka, S., Bradshaw, D. H., Jacobson, R. C., & Donaldson, G. W. (1999). Phasic pupil dilation response to noxious stimulation in normal volunteers: Relationship to brain evoked potentials and pain report. Psychophysiology, 36, 4452. doi: 10.1017/S0048577299970373
Chapman, L., & Hallowell, B. (2015). A novel pupillometric method for indexing word difficulty in individuals with and without aphasia. Journal of Speech, Language, and Hearing Research, 58, 15081520. doi: 10.1044/2015
Cohen Hoffing, R., & Seitz, A. (2015). Pupillometry as a glimpse into the neurochemical basis of human memory encoding. Journal of Cognitive Neuroscience, 27, 765774. doi: 10.1162/jocn
Conklin, K., & Pellicer-Sanchez, A. (2016). Using eye-tracking in applied linguistics and second language research. Second Language Research, 32, 453467. doi: 10.1177/0267658316637401
Demberg, V., & Sayeed, A. (2016). The frequency of rapid pupil dilations as a measure of linguistic processing difficulty. PLoS ONE, 11, 129. doi: 10.1371/journal.pone.0146194
Duñabeitia, J. A., & Costa, A. (2014). Lying in a native and foreign language. Psychonomic Bulletin and Review, 22, 11241129. doi: 10.3758/s13423-014-0781-4
Eckstein, M. K., Guerra-Carrillo, B., Singley, A. T. M., & Bunge, S. A. (2016). Beyond eye gaze: What else can eyetracking reveal about cognition and cognitive development? Developmental Cognitive Neuroscience, 25, 6991. doi: 10.1016/j.dcn.2016.11.001
Ellis, N. C. (2005). At the interface: Dynamic interactions of explicit and implicit language knowledge. Studies in Second Language Acquisition, 27, 305352. doi: 10.1017/S027226310505014X
Ellis, R. (2005). Measuring implicit and explicit knowledge of a second language: A psychometric study. Studies in Second Language Acquisition, 27, 141172. doi: 10.1017/S0272263105050096
Engelhardt, P. E., Ferreira, F., & Patsenko, E. G. (2010). Pupillometry reveals processing load during spoken language comprehension. Quarterly Journal of Experimental Psychology, 63, 639645. doi: 10.1080/17470210903469864
Foote, R. (2015). The storage and processing of morphologically complex words in L2 Spanish. Studies in Second Language Acquisition, 133. doi: 10.1017/S0272263115000376
Gagl, B., Hawelka, S., & Hutzler, F. (2011). Systematic influence of gaze position on pupil size measurement: analysis and correction. Behavior Research Methods, 43, 11711181. doi: 10.3758/s13428-011-0109-5
Geller, J., Still, M. L., & Morris, A. L. (2015). Eyes wide open: Pupil size as a proxy for inhibition in the masked-priming paradigm. Memory and Cognition, 44, 554564. doi: 10.3758/s13421-015-0577-4
Gilzenrat, M., Nieuwenhuis, S., Jepma, M., & Cohen, J. D. (2010). Pupil diameter tracks changes in control state predicted by the adaptive gain theory of locus coeruleus function. Cognitive, Affective, and Behavioral Neuroscience, 10, 252269. doi: 10.3758/CABN.10.2.252.Pupil
Godfroid, A., Loewen, S., Jung, S., Park, J.-H., Gass, S., & Ellis, R. (2015). Timed and untimed grammaticality judgments measure distinct types of knowledge. Studies in Second Language Acquisition, 37, 269297. doi: 10.1017/S0272263114000850
Goldinger, S. D., & Papesh, M. H. (2012). Pupil dilation reflects the creation and retrieval of memories. Current Directions in Psychological Science, 21, 9095. doi: 10.1177/0963721412436811
Gollan, T. H., Montoya, R. I., Cera, C., & Sandoval, T. C. (2008). More use almost always means a smaller frequency effect: Aging, bilingualism, and the weaker links hypothesis. Journal of Memory and Language, 58, 787814. doi: 10.1016/j.jml.2007.07.001
Granholm, E., & Steinhauer, S. R. (2004). Pupillometric measures of cognitive and emotional processes. International Journal of Psychophysiology: Official Journal of the International Organization of Psychophysiology, 52, 16. doi: 10.1016/j.ijpsycho.2003.12.001
Guasch, M., Ferré, P., & Haro, J. (2016). Pupil dilation is sensitive to the cognate status of words: Further evidence for non-selectivity in bilingual lexical access. Bilingualism: Language and Cognition, 20, 4954. doi: 10.1017/S1366728916000651
Hardison, D. M. (2005). Second-language spoken word identification: Effects of perceptual training, visual cues, and phonetic environment. Applied Psycholinguistics, 26, 579596.
Haro, J., Guasch, M., Vallès, B., & Ferré, P. (2016). Is pupillary response a reliable index of word recognition? Evidence from a delayed lexical decision task. Behavior Research Methods. Advance online publication. doi: 10.3758/s13428-016-0835-9
Hayes, T. R., & Petrov, A. A. (2015). Mapping and correcting the influence of gaze position on pupil size measurements. Behavior Research Methods, 48, 510527. doi: 10.3758/s13428-015-0588-x
Heinrich, W. (1896). Die Aufmerksamkeit und die Funktion der Sinnesorgane. Zeitschrift Für Psychologie Und Physiologie Der Sinnesorgane, 9, 342388.
Hess, E. H., & Polt, J. M. (1964). Pupil size in relation to mental activity during simple problem-solving. Science, 143, 11901192.
Hochmann, J.-R., & Papeo, L. (2014). The invariance problem in infancy: A pupillometry study. Psychological Science, 25, 20382046. doi: 10.1177/0956797614547918
Hyönä, J., Tommola, J., & Alaja, A. (1995). Pupil dilation as a measure of processing load in simultaneous interpretation and other language tasks. The Quarterly Journal of Experimental Psychology Section A: Human Experimental Psychology, 43, 598612.
Ivanova, I., & Costa, A. (2008). Does bilingualism hamper lexical access in speech production? Acta Psychologica, 127, 277–88. doi: 10.1016/j.actpsy.2007.06.003
Jegerski, J., & VanPatten, B. (2014). Research methods in second language psycholinguistics. London: Routledge.
Joshi, S., Li, Y., Kalwani, R. M., & Gold, J. I. (2016). Relationships between pupil diameter and neuronal activity in the locus coeruleus, colliculi, and cingulate cortex. Neuron, 89, 221234. doi: 10.1016/j.neuron.2015.11.028
Just, M. A., & Carpenter, P. A. (1993). The intensity dimension of thought: Pupillometric indices of sentence processing. Canadian Journal of Experimental Psychology, 47, 310339.
Kahneman, D., & Beatty, J. (1966). Pupil diameter and load on memory. Science, 154, 15831585.
Keating, G. D., & Jegerski, J. (2015). Experimental designs in sentence processing research: A methodological review and user’s guide. Studies in Second Language Acquisition, 37, 132. doi: 10.1017/S0272263114000187
Klingner, J., Tversky, B., & Hanrahan, P. (2011). Effects of visual and verbal presentation on cognitive load in vigilance, memory, and arithmetic tasks. Psychophysiology, 48, 323332. doi: 10.1111/j.1469-8986.2010.01069.x
Koch, X., & Janse, E. (2016). Speech rate effects on the processing of conversational speech across the adult life span. Journal of the Acoustical Society of America, 139, 16181636. doi: 10.1121/1.4944032
Kohn, M., & Clynes, M. (1969). Color dynamics of the pupil. Annals of the New York Academy of Sciences, 156, 931950. doi: 10.1111/j.1749-6632.1969.tb14024.x
Kramer, S. E., Lorens, A., Coninx, F., Zekveld, A. A., Piotrowska, A., & Skarzynski, H. (2013). Processing load during listening: The influence of task characteristics on the pupil response. Language and Cognitive Processes, 28, 426442. doi: 10.1080/01690965.2011.642267
Kuchinke, L., , M. L.-H., Hofmann, M., & Jacobs, A. M. (2007). Pupillary responses during lexical decisions vary with word frequency but not emotional valence. International Journal of Psychophysiology, 65, 132–40. doi: 10.1016/j.ijpsycho.2007.04.004
Kuchinsky, S. E., Ahlstrom, J. B., Vaden, K. I., Cute, S. L., Humes, L. E., Dubno, J. R., et al. . (2013). Pupil size varies with word listening and response selection difficulty in older adults with hearing loss. Psychophysiology, 50, 2334. doi: 10.1111/j.1469-8986.2012.01477.x
Laeng, B., Ørbo, M., Holmlund, T., & Miozzo, M. (2011). Pupillary Stroop effects. Cognitive Processing, 12, 1321. doi: 10.1007/s10339-010-0370-z
Laeng, B., Sirois, S., & Gredeback, G. (2012). Pupillometry: A window to the preconscious? Perspectives on Psychological Science, 7, 1827. doi: 10.1177/1745691611427305
Leal, T., Slabakova, R., & Farmer, T. A. (2016). The fine-tuning of linguistic expectations over the course of L2 learning. Studies in Second Language Acquisition. Advance online publication. doi: 10.1017/S0272263116000164
Ledoux, K., Coderre, E., Bosley, L., Buz, E., Gangopadhyay, I., & Gordon, B. (2016). The concurrent use of three implicit measures (eye movements, pupillometry, and event-related potentials) to assess receptive vocabulary knowledge in normal adults. Behavior Research Methods, 48, 285305. doi: 10.3758/s13428-015-0571-6
McGarrigle, R., Dawes, P., Stewart, A. J., Kuchinsky, S. E., & Munro, K. J. (2016). Pupillometry reveals changes in physiological arousal during a sustained listening task. Psychophysiology, 54, 193203. doi: 10.1111/psyp.12772
Meador, D., Flege, J. E., & Mackay, R. (2000). Factors affecting the recognition of words in a second language. Bilingualism: Language and Cognition, 3, 5567.
Murphy, P. R., O’Connell, R. G., O’Sullivan, M., Robertson, I. H., & Balsters, J. H. (2014). Pupil diameter covaries with BOLD activity in human locus coeruleus. Human Brain Mapping, 35, 41404154. doi: 10.1002/hbm.22466
Nassar, M. R., Rumsey, K. M., Wilson, R. C., Parikh, K., Heasly, B., & Gold, J. I. (2012). Rational regulation of learning dynamics by pupil-linked arousal systems. Nature Neuroscience, 15, 1040–6. doi: 10.1038/nn.3130
Papesh, M. H., & Goldinger, S. D. (2012). Pupil-BLAH-metry: Cognitive effort in speech planning reflected by pupil dilation. Attention, Perception and Psychophysics, 74, 754–65. doi: 10.3758/s13414-011-0263-y
Piquado, T., Isaacowitz, D., & Wingfield, A. (2010). Pupillometry as a measure of cognitive effort in younger and older adults. Psychophysiology, 47, 560569. doi: 10.1111/j.1469-8986.2009.00947.x
Pomplun, M., & Sunkara, S. (2003). Pupil dilation as an indicator of cognitive workload in human-computer interaction. In Harris, D., Duffy, V., Smith, M., & Stephanidis, C. (Eds.), Human-centered computing: Cognitive, social and ergonomic aspects. Vol. 3 of the Proceedings of the 10th International Conference on Human-Computer Interaction (pp. 542546). Crete, Greece.
Runnqvist, E., Strijkers, K., Sadat, J., & Costa, A. (2011). On the temporal and functional origin of l2 disadvantages in speech production: A critical review. Frontiers in Psychology, 2, 379. doi: 10.3389/fpsyg.2011.00379
Samuels, E., & Szabadi, E. (2008a). Functional neuroanatomy of the noradrenergic locus coeruleus: Its roles in the regulation of arousal and autonomic function part I: Principles of functional organisation. Current Neuropharmacology, 6, 235253. doi: 10.2174/157015908785777229
Samuels, E., & Szabadi, E. (2008b). Functional neuroanatomy of the noradrenergic locus coeruleus: Its roles in the regulation of arousal and autonomic function part II: Physiological and pharmacological manipulations and pathological alterations of locus coeruleus activity in humans. Current Neuropharmacology, 6, 254285. doi: 10.2174/157015908785777193
Sara, S. J. (2009). The locus coeruleus and noradrenergic modulation of cognition. Nature Reviews Neuroscience, 10, 211223. doi: 10.1038/nrn2573
Sara, S. J., & Bouret, S. (2012). Orienting and reorienting: The locus coeruleus mediates cognition through arousal. Neuron, 76, 130141. doi: 10.1016/j.neuron.2012.09.011
Scheepers, C., Mohr, S., Fischer, M. H., & Roberts, A. M. (2013). Listening to limericks: A pupillometry investigation of perceivers’ expectancy. PLoS ONE, 8, e74986. doi: 10.1371/journal.pone.0074986
Schmidtke, J. (2014). Second language experience modulates word retrieval effort in bilinguals: Evidence from pupillometry. Frontiers in Psychology, 5, 116. doi: 10.3389/fpsyg.2014.00137
Schmitt, N. (2014). Size and depth of vocabulary knowledge: What the research shows. Language Learning, 64, 913951. doi: 10.1111/lang.12077
Sirois, S., & Brisson, J. (2014). Pupillometry. Wiley Interdisciplinary Reviews: Cognitive Science, 5, 679692. doi: 10.1002/wcs.1323
Tamási, K., McKean, C., Gafos, A., Fritzsche, T., & Höhle, B. (2016). Pupillometry registers toddlers’ sensitivity to degrees of mispronunciation. Journal of Experimental Child Psychology, 153, 140148. doi: 10.1016/j.jecp.2016.07.014
Tanenhaus, M. K., Spivey-Knowlton, M. J., Eberhard, K. M., & Sedivy, J. C. (1995). Integration of visual and linguistic information in spoken language comprehension. Science, 268, 16321634.
Tromp, J., Hagoort, P., & Meyer, A. S. (2015). Pupillometry reveals increased pupil size during indirect request comprehension. Quarterly Journal of Experimental Psychology, 69, 10931108. doi: 10.1080/17470218.2015.1065282
VanPatten, B., & Smith, M. (2014). Aptitude as grammatical sensitivity and the initial stages of learning Japanese as a L2. Studies in Second Language Acquisition, 37, 135165. doi: 10.1017/S0272263114000345
Wagner, A. E., Toffanin, P., & Baskent, D. (2016). The timing and effort of lexical access in natural and degraded speech. Frontiers in Psychology, 7, 114. doi: 10.3389/fpsyg.2016.00398
Wang, C. A., & Munoz, D. P. (2015). A circuit for pupil orienting responses: Implications for cognitive modulation of pupil size. Current Opinion in Neurobiology, 33, 134140. doi: 10.1016/j.conb.2015.03.018
Weber, A., & Broersma, M. (2012). Spoken word recognition in second language acquisition. In Chapelle, C. A. (Ed.), The encyclopedia of applied linguistics (pp. 53685375). Bognor Regis, UK: Wiley-Blackwell. doi: 10.1002/9781405198431
Wendt, D., Dau, T., & Hjortkjaer, J. (2016). Impact of background noise and sentence complexity on processing demands during sentence comprehension. Frontiers in Psychology, 7, 112. doi: 10.3389/fpsyg.2016.00345
Zekveld, A. A., Kramer, S. E., & Festen, J. M. (2010). Pupil response as an indication of effortful listening: the influence of sentence intelligibility. Ear and Hearing, 31, 480490. doi: 10.1097/AUD.0b013e3181d4f251
Zellin, M., Pannekamp, A., Toepel, U., & van der Meer, E. (2011). In the eye of the listener: Pupil dilation elucidates discourse processing. International Journal of Psychophysiology: Official Journal of the International Organization of Psychophysiology, 81, 133141. doi: 10.1016/j.ijpsycho.2011.05.009
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Studies in Second Language Acquisition
  • ISSN: 0272-2631
  • EISSN: 1470-1545
  • URL: /core/journals/studies-in-second-language-acquisition
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
Type Description Title
Supplementary materials

Schmidtke supplementary material
Schmidtke supplementary material 1

 Word (129 KB)
129 KB


Altmetric attention score

Full text views

Total number of HTML views: 33
Total number of PDF views: 184 *
Loading metrics...

Abstract views

Total abstract views: 797 *
Loading metrics...

* Views captured on Cambridge Core between 22nd August 2017 - 19th March 2018. This data will be updated every 24 hours.