skip to content

Recent Lab Publications (2016-present):

 

Submitted

 

Schnell, A., Boeckle, M., Rivera, M., Clayton, N. S. & Hanlon, R. T. Cuttlefish exhibit self-control in a delay of gratification task. Proceedings of the Royal Society

 

Schnell, A., Loconsole, M., Garcia-Pelegrin, E., Wilkins, C. & Clayton, N. S. Jays are sensitive to cognitive illusions. Royal Society Open Science

 

Chow, P. K. Y., Clayton, N. S. & Steele, M. Cognitive and behavioural flexibility in grey squirrels: A test of the ‘inherent superiority hypothesis’. Frontiers in Ecology and Evolution

 

Crosby, R. M., Legg, E. W., Brecht, K. F., Mendl, M. T, Ostojić, L. & Clayton, N. S.  Male Eurasian jays flexibly alter their food sharing in line with partners’ choices. Animal Behavior and Cognition

 

Ding N, Frohnwieser A, *Miller R, *Clayton NS (* = joint senior authorship). Waiting for a better reward: comparison of delay of gratification in young children across two cultures. Cognition

 

Lewis, L.S., Kano, F., Stevens, J.M.G, DuBois, J.G., Call, J., Krupenye, C. Bonobos and chimpanzees preferentially attend to familair members of the dominant sex. Animal Behaviour

 

Accepted

 

Miller R, Schiestl M, Clayton NS. (Accepted) Book Chapter: Welfare in Corvids. 9th Ed of Universities Federation for Animal Welfare Handbook on Care and Management of Laboratory and Other Research Animals. Wiley

 

In press

 

Schnell, A. & Clayton, N. S. (In press). Evolutionary origins of complex cognition. In: Evolution of learning and memory mechanisms, Ed.  M. Krause, K. Hollis, M. Papini

 

Santiesteban, I., Gibbard, C., Drucks, H., Clayton, N. S., Banissy, M. J. & Bird, G.  (In press). Individuals with Autism Share Others’ Emotions: Evidence from the Continuous Affective Rating ad Empathic Responses (CARER) Task. Journal of Autism and Developmental Disorders.

 

Billard, P., Clayton, N. S. & Jozet-Alves, C. (In press). Episodic Memory. Encyclopaedia of Animal Cognition and Behaviour. Shakleford, T. & Vonk, J. Eds.

 

Schnell, A. & Clayton, N. S. (In press) Cephalopods: Ambassadors for rethinking cognition. Biochemical and Biophysical Research Communications

 

2021

Amodio*, P., Brea*, J., Farrar, B.G., Ostojic ́, L. and Clayton, N.S. Testing two competing hypotheses for Eurasian jays’ caching for the future. Sci Rep 11, 835 (2021). https://doi.org/10.1038/s41598-020-80515-7

 

Schnell, A.  K., Amodio, A., Boeckle, M. & Clayton, N. S. (2021). How intelligent is a cephalopod? Lessons from Comparative Cognition. Biological Reviews. 96, 162–178.

 

2020

 

Boeckle M, Schiestl M, Frohnwieser A, Gruber R, Miller R, Suddendorf T, Gray RD, Taylor AH, Clayton NS. (2020) New Caledonian crows flexibly plan for specific future tool use. Proceedings of the Royal Society B: Biological Sciences 287: 20201490

 

Miller R & Gruber R, Frohnwieser A, Schiestl M, Jelbert SA, Gray RD, Boeckle M, Taylor AH, Clayton NS. (2020) Decision-making flexibility in New Caledonian crows, young children and adult humans in a multi-dimensional tool-use task. PLoS ONE 15: e0219874

 

Miller R, Frohnwieser A, Ding N, Troisi C, Schiestl M, Gruber R, Taylor AH, Gray RD, Jelbert SA, Boeckle M, Clayton NS. (2020) A novel test of flexible planning in relating to executive function and language in young children. Royal Society Open Science 7: 71-85

 

Amodio, P., Shigeno, S., and Ostojic ́, L. Evolution of Intelligence in Cephalopods, eLS, Vol 1: 77–84, 2020. DOI: 10.1002/9780470015902.a0029004

 

Baciadonna, L., Cornero, F., Emery, N. J. & Clayton, N. S. (2020). Convergent evolution of complex cognition: Insights from the field of avian cognition into the study of self-awareness. Learning and Behaviour https://doi.org/10.3758/s13420-020-00434-5

 

Farrar, B. G., Altschul, D. M., Fischer, J., van der Mesacht, J., Placi, S., Troisi, C. A., Vernouillet, A., Clayton, N. S. & Ostojić, L. (2020). Trialling meta-research in comparative cognition: Claims and statistical inference in animal physical cognition. Animal Behavior and Cognition 7(3), 419-444. https://doi.org/10.26451/abc.07.03.09.2020

 

Birch, J., Schnell, A. K. & Clayton, N. S. (2020). Dimensions of Animal Consciousness. Trends in Cognitive Science 24: 798-801 https://doi.org/10.1016/j.tics.2020.07.007

 

Cabrera-Álvarez, M. J. & Clayton, N. S.  (2020). Neural Processes Underlying Tool Use in Humans, Macaques, and Corvids. Frontiers in Psychology, section Comparative Psychology.

 

Garcia-Pelegrin, E., Schnell, A. K., Wilkins, C. & Clayton, N. S.  (2020). An unexpected audience: Experiments with magic effects might be informative about cognition in animals, Science 369 (6510), 1424-1426.

 

Cornero, F. M. & Clayton, N. S. (2020). The mental lives of parrots. Current Biology 30, R371–R39

 

Amodio, P., Boeckle, M., Jelbert, S. A., Ostojić, L., & Clayton, N. S. (2020). How flexible is tool use in Eurasian jays (Garrulus glandarius)?. bioRxiv, 803700. Animal Behavior and Cognition

 

Farrar, B. G., Boeckle, M. & Clayton, N. S. (2020). Replications in comparative cognition: what should we expect and how can we improve? Animal Behavior and Cognition 7, 1-22.

 

Billard, P., Schnell, A. K., Clayton, N. S. & Jozet-Alves, C. (2020) Cuttlefish show flexible and future-oriented foraging cognition. Biology Letters 16, 20190743

 

Billard, P., Jozet-Alves, C. & Clayton, N. S. (2020). Source-memory at the interface between content and phenomenology. Scientific Reports 10, 5413

 

Samuel, S., Frohnwieser, A. Lurz, R. & Clayton, N. S. (2020). Reduced egocentric bias when perspective-taking compared to working from rules. Quarterly Journal of Experimental Psychology https://doi.org/10.1177/1747021820916707

 

2019

 

Miller R, Frohnwieser A, Schiestl M, McCoy DE, Gray RD, Taylor AH, Clayton NS. (2019) Delayed gratification in New Caledonian crows and young children: influence of reward type and visibility. Animal Cognition: 1-15 doi: 10.1007/s10071-019-01317-7

 

Miller, R., Boeckle, M., Frohnwieser, A., Jelbert, S., Wascher, C., & Clayton, N. (2019). Self-control in crows, parrots and non-human primates.

 

Amodio, P. (2019). Octopus intelligence: The importance of being agnostic. Animal Sentience 26(20). DOI: 10.51291/2377-7478.1507

 

Shaw, R. C., MacKinlay, R. D., Clayton, N. S., & Burns, K. C. (2019). Memory performance influences male reproductive success in a wild bird. Current Biology.

 

Gruber, R., Schiestl, M., Boeckle, M., Frohnwieser, A., Miller, R., Gray, R. D., ... & Taylor, A. H. (2019). New Caledonian crows use mental representations to solve metatool problems. Current Biology, 29(4), 686-692.

 

Samuel, S., Roehr-Brackin, K., Jelbert, S., & Clayton, N. S. (2019). Flexible egocentricity: Asymmetric switch costs on a perspective-taking task. Journal of Experimental Psychology: Learning, Memory, and Cognition, 45(2), 213.

 

Jelbert, S. A., Miller, R., Schiestl, M., Boeckle, M., Cheke, L. G., Gray, R. D., ... & Clayton, N. S. (2019). New Caledonian crows infer the weight of objects from observing their movements in a breeze. Proceedings of the Royal Society B, 286(1894), 20182332.

 

Hackett, P. M., Shaw, R. C., Boogert, N. J., & Clayton, N. S. (2019). A Facet Theory Analysis of the Structure of Cognitive Performance in New Zealand Robins (Petroica longipes). International Journal of Comparative Psychology, 32.

 

Samuel, S., Durdevic, K., Legg, E. W., Lurz, R., & Clayton, N. S. (2019). Is Language Required to Represent Others’ Mental States? Evidence From Beliefs and Other Representations. Cognitive science, 43(1), e12710.

 

Schnell, A.  & Clayton, N. S. (2019). Cephalopod cognition: A primer. Current Biology. 26, R726–R732

 

Amodio, P., Fiorito, G., Clayton, N. S., & Ostojić, L. (2019). Commentary: A Conserved Role for Serotonergic Neurotransmission in Mediating Social Behavior in Octopus. Frontiers in Behavioral Neuroscience, 13, 185.

 

Samuel, S., Legg, E. W., Manchester, C., Lurz, R. & Clayton, N. S. (2020). Where was I? Taking an alternative visual perspective can makes us (briefly) briefly forget our own.  Quarterly Journal of Experimental Psychology 73, 468-477.

 

Wilkins, C. A. P. & Clayton, N. S. (2019). Reflections on the Spoon Test. An essay in honor of Endel Tulving.  NeuroPsychologia 134, 107221 https://doi.org/10.1016/j.neuropsychologia.2019.107221

 

Clayton, N. S. (2019). My Word: Cognition. Current Biology 26, R1-9

 

Wilkins, C. A. P. & Clayton, N. S. (2019). Mind Tricks. Magic and mysticism reveal cognitive shortcuts with implications beyond entertainment. Science 364, 6445.

 

Clayton, N. S. & Wilkins, C. A. P. (2019). Book review of Tricks of the Mind. Experiencing the Impossible. Current Biology 29(10), R349-R350

 

Plotnik, J. M., Brubacker, D. L. Dale, R., Tiller, L. N., Mumby, H. S. & Clayton, N. S. (2019). Elephants have a nose for quantity. Proceedings of the Natural Academy of Science 116(25), 12566-12511.

 

Amodio, P., Boeckle, M., Schnell, A., Ostojic, L., Fiorito, G., and Clayton, N. S. (2019). Shell Loss in Cephalopods: Trigger for, or By-Product of, the Evolution of Intelligence? A Reply to Mollo et al. Trends in Ecology & Evolution 34, 690–692.

 

Samuel, S., Durdevik, K., Legg, E. W., Lurz, R. & Clayton, N. S. (2019). Is language required to represent others’ mental states? Evidence from beliefs and other representations. Cognitive Science, 43(1), 1-18.

 

Shaw, R. C., MacKinlay, R. D., Clayton, N. S. & Burns, K. C. (2019). Spatial memory ability influences male reproductive success in a food caching bird. Current Biology 29(9), 1498-1502.

 

Hackett, P., Shaw, R. C., Boogert, N. J. & Clayton, N. S. (2019). The Structure of Cognitive Performance in New Zealand Robins (Petroica longipes): a Faceted Analysis of Shaw et al's (2015) Data Matrix. International Journal of Comparative Psychology 32, 1-26.

 

Cheke, L. G. & Clayton, N. S. (2019). What is the role of episodic foresight in planning for future needs? Theory and two experiments

 

Amodio, P., Boeckle, M., Schnell, A. K., Ostojić, L., Fiorito, G., & Clayton, N. S. (2019). Grow Smart and Die Young: Why Did Cephalopods Evolve Intelligence?. Trends in ecology & evolution. 34, 45–56.

 

2018

  

Samuel, S., Legg, E. W., Lurz, R., & Clayton, N. S. (2018). The unreliability of egocentric bias across self–other and memory–belief distinctions in the Sandbox Task. Royal Society open science, 5(11), 181355.

 

Samuel, S., Legg, E. W., Lurz, R., & Clayton, N. S. (2018). Egocentric bias across mental and non-mental representations in the Sandbox Task. Quarterly Journal of Experimental Psychology, 71(11), 2395-2410.

 

Greggor AL, McIvor GE, Clayton NS, Thornton A. 2018. Wild jackdaws are wary of objects that violate expectations of animacy. Open Science. 5 (10), 181070

 

Amodio P, Jelbert SA, Clayton NS. 2018. The interplay between psychological predispositions and skill learning in the evolution of tool use. Current opinion in behavioral sciences. 20, 130-137

 

Samuel SH, Roehr-Brackin K, Jelbert S, Clayton NS. 2018. Flexible egocentricity: Asymmetric switch costs on a perspective-taking task. APA [Data]

 

Bretch KF, Ostojic L, Legg EW, Clayton NS. 2018. Difficulties when using video playback to investigate social cognition in California scrub-jays (Aphelocoma californica). PeerJ 6, e4451

 

Loissel E, Cheke LG, Clayton NS. 2018. Exploring the relative contributions of reward-history and functionality information to children's acquisition of the Aesop's fable task. PloS one. 13 (2), e0193264

 

Boeckle M, Clayton NS. 2018. Theory of Mind. Encyclopedia of Animal Cognition and Behavior. 1-12

 

Samuel SH, Clayton NS. 2018. Morgan's canon is not evidence. Behavioral and Brain Sciences. 41, e31

 

Loissel, E., Cheke, L. G. & Clayton, N. S. (2018). Exploring the Relative Contributions of Reward-History and Functionality Information in The Aesop’s Fable Task. PLoS ONE 13, e0193264.

 

Brecht, K. F., Ostojić, L., Legg, E. W. & Clayton, N. S. (2018). Difficulties when using video playback to investigate social cognition in California scrub-jays (Aphelocoma californica). Peer J 6, e4451 DOI 10.7717/peerj.4451

 

Greggor, A. L., McIvor, G. E., Clayton, N. S. & Thornton, J. A. N. (2018). Judgements of animacy guide jackdaw’s responses to environmental stimuli in the wild. Royal Society Open Science 5, 181070.

 

Clayton, N. S. & Wilkins, C. A. P. (2018). Seven Myths of Memory. Behavioural Processes, 152, 3-9.

 

2017

 

Davidson G, Miller R, Loissel E, Cheke LG, Clayton NS. 2017. The development of support intuitions and object causality in juvenile Eurasian jays (Garrulus glandarius). Scientific Reports. 7, 40062 [Erratum]

 

Clayton NS, Wilkins C. 2017. Seven myths of memory. Behavioural processes. 152, 3-9

 

Bretch KF, Wagener L, Ostojic L, Clayton NS, Nieder A. 2017. Comparing the face inversion effect in crows and humans. Journal of Comparative Physiology. 203 (12), 1017-1027

 

Samuel SH, Legg EW, Lurz R, Clyaton NS. 2017. Egocentric bias across mental and non-mental representations in the Sandbox Task. Quarterly Journal of Experimental Psychology. 1747021817742367

 

Jelbert SA, Clayton NS. 2017. Comparing the non-linguistic hallmarks of episodic memory systems in corvids and children. Current Opinion in Behavioral Sciences. 17, 99-106

 

Samuel SH, Clayton NS. 2017. Morgan's Cannon is not evidence (Commentary on Mahr & Csibra). Cambridge University Press

 

Legg EW, Olivier L, Samuel SH, Lurz R, Clayton NS. 2017. Error rate on the director's task is influenced by the need to take another's perspective but not the type of perspective. Royal Society Open Science. 4 (8), 170284 

 

Miller R, Jelbert SA, Loissel E, Taylor AH, Clayton NS. 2017. Young children do not require perceptual-motor feedback to solve Aesop's fable tasks. PeerJ. 5, e3484

 

Boeckle M, Clayton NS. 2017. A raven's memories are for the future. Science. 357 (6347), 126-127

 

Kelley LA, Clayton NS. 2017. California scrub-jays reduce visual cues available to potential pilferers by matching food colour to caching substrate. Biology Letters. 13 (7), 20170242

 

Clayton NS, Wilkins C. 2017. Memory, mental time travel and The Moustachio Quartet. Interface focus. 7 (3), 20160112

 

Powell R, Mikhalevich I, Logan C, Clayton NS. 2017. Convergent minds: the evolution of cognitive complexity in nature. Interface focus. 7 (3), 20170029

 

Shaw RC, MacKinlay RD, Clayton NS, Burns KC. 2017. Male New Zealand robins (Petroica longpipes) cater to their mate's desire when sharing food in the wild. Scientific Reports. 7 (1), 896

 

Greggor AL, Spencer KA, Clayton NS, Thornton A. 2017. Wild jackdaws' reproductive success and their offspring's stress hormones are connected to provisioning rate and brood size, not to parental neophobia. General and comparative endocrinology. 243, 70-77

 

Cheke LG, Bonnici HM, Clayton NS, Simons JS. 2017. Obesity and insulin resistance are associated with reduced activity in core memory regions of the brain. Neuropsychologia. 96, 137-149

 

Ostojic L, Legg EW, Brecht KF, Lange F, Deininger C, Mendl M, Clayton NS. 2017. Current desires of conspecific observers affect cache-protection strategies in California scrub-jays and Eurasian jays. Current Biology. 27 (2), R51-R53

 

Davies KM, Cheke LG, Clayton NS. 2017. Episodic memory as an explanation for the insurance hypothesis in obesity. Behavioral and Brain Sciences. 40

 

Davidson GL, Thorton A, Clayton NS. 2017. Evolution of iris colour in relation to cavity nesting and parental care in passerine birds. Biology Letters. 13 (1), 20160783

 

Greggor AL, Thorton A, Clayton NS. 2017. Harnessing learning biases is essential for applying social learning in conservation. Behavioral Ecology and Sociobiology. 71 (1), 16

 

Clayton NS. 2017. Episodic-like memory and mental time travel in animals. American Psychological Association Handbook of Comparative Psychology. 11, 227-243

 

Clayton, N. S. & Wilkins, C. A. P.  (2017). The Creative Navigator’s Compass: Memory and Perception~ and how we know which way we are facing. The Psychologist 35, 10-14.

 

Greggor, A. L., Thornton, J. A. N., Spencer, K. A. & Clayton, N. S.  (2017). Assessing connections between parental neophobia and offspring corticosterone levels in a fearful corvid. General and Comparative Endocrinology 243, 70-77.

 

Ostojić, L., Legg, E. W., Brecht, K. F., Lange, F., Deininger, C., Mendl M. & Clayton, N. S. (2017). Current desires of conspecific observers affect cache- protection strategies in California scrub-jays and Eurasian jays. Current Biology 27, R43-56.

 

Cheke, L. G., Bonnici, H., Clayton, N. S. & Simons, J. S. (2017). Obesity and Insulin Resistance are Associated with Reduced Activity in Core Memory Regions of the Brain. Neuropsychologia 96, 137-149

 

Davies, K., Cheke, L. G. & Clayton, N. S. (2017). Commentary Proposal on Nettle et al. 2016. Episodic memory as an explanation for the insurance hypothesis in obesity. Behavioral Brain Sciences 40, e113. doi:10.1017/S0140525X16001382

 

Legg, E. W., Ostojić, L., & Clayton. N. S.  (2017). Routes to the Convergent Evolution of Cognition. Chapter 17, 237–251. In: Routledge Handbook of Evolution and Philosophy, Ed. by Joyce, R.

 

Clayton, N. S. (2017). Episodic-Like Memory and Mental Time Travel in Animals. Chapter 11, pp. 227-243. In: Call, J. APA Handbook of Comparative Psychology. Volume 2. Perception, Learning & Cognition.

 

Shaw, R. C., Mackinlay, R. D., Clayton. N. S. & Burns, K. C. Wild male North Island robins cater to their mate’s desire when sharing food. Scientific Reports 7, 896.

 

Powell, R., Mikhalevich, I., Logan, C. & Clayton, N. S. Convergent Minds: The Evolution of Cognitive Complexity in Nature. Royal Society Interface Focus 30, 1-8.

 

Clayton, N. S. & Wilkins, C. (2017). Memory, Mental Time Travel and the Moustachio Quartet. Royal Society Interface Focus 30, 22-26.

 

Legg, E. W, Olivier, L., Samuel, S., Lurz, R. & Clayton, N. S. (2017). Error rate on the director’s task is influenced by the need to take another’s perspective but not the type of perspective. Royal Society Open Science 4 (8), 170284.

 

Kelley, L. A. & Clayton. N. S. (2017). California scrub-jays reduce visual cues available to potential pilferers by matching food colour to caching substrate. Biology Letters 13, 20170242.

 

Samuel, S. & Clayton, N. S. (2017). Morgan’s Canon is not evidence [Commentary on Mahr & Csibra]. Behavioral Brain Sciences 41, 41-42. doi:10.1017/S0140525X17001509, e31

 

Brecht, K. F., Wagener, L., Ostojić, L., Clayton, N. S.  & Nieder, A. (2017). Comparing the face inversion effect in crows and humans. Journal of Comparative Physiology A 203, 1017-1027.

 

Logan, C. J. & Clayton, N. S. (2017). Rook, jackdaw, and Eurasian jay post-conflict affiliation data. Knowledge Network for Biocomplexity doi:10.5063/F1FB5124. https://knb.ecoinformatics.org/#view/doi:10.5063/F1FB5124

 

Clayton, N. S. (2017). Book review: Mandela’s Dancers: Oral Histories of Program Participants and Organisers, review by Prof. Nicky Clayton. Hotfoot, Spring issue, p. 47.

 

2016

 

Miller R, Jelbert SA, Taylor AH, Cheke LG, Gray RD, Loissel E, Clayton NS (2016) Performance in object-choice Aesop’s Fable tasks are influenced by object biases in New Caledonian crows but not in human children. PLoS ONE 11:e0168056

 

Miller R, Logan CJ, Lister K, Clayton NS (2016). Eurasian jays do not copy the choices of conspecifics, but they do show evidence of stimulus enhancement. Peer J 4:e2746

 

Davidson, G. & Clayton, N. S. (2016). New Perspectives in Gaze Sensitivity. Learning and Behavior, 44, 9-17.

 

Watanabe, A. & Clayton. N. S. (2016). Hint-Seeking Behaviour of Western Scrub-Jays in a Metacognition Task. Animal Cognition 19, 53-64.

 

Ostojić, L., Cheke, L. G., Shaw, R. C., Legg, E. W. & Clayton, N. S. (2016). Desire-state attribution: benefits of a novel paradigm using the food-sharing behaviour of Eurasian jays (Garrulus glandarius). Communicative & Integrative Biology 9 (1):e1134065.

 

Cheke, L. G., Simons, J. S & Clayton, N. S.  (2016). Higher BMI is Associated with Episodic Memory Deficits in Young Adults.  Quarterly Journal of Experimental Psychology 69, 2305-2316.

 

Thom, J. M. & Clayton, N. S. (2016). Evolutionary Perspectives on Prospective Cognition. In: Klein, B. Michaelian, K. & Szpunar, K.K. Seeing the future: Theoretical perspectives on future-oriented mental time travel. Oxford University Press. Chapter 14, pp. 287-305.

 

Laland, K., Wilkins C. A. P. & Clayton, N. S. (2015). The Evolution of Dance. Current Biology 26, R5-9.

 

Greggor, A. L., Clayton, N. S., Fulford, A. & Thornton, J. A. N. (2016). Street smart: faster approach towards litter in urban areas by highly neophobic corvids and less fearful birds. Animal Behaviour 117, 123-133.

 

Legg, E. W., Ostojić, L. & Clayton. N. S. (2016). Caching at a distance: a cache protection strategy in Eurasian jays. Animal Cognition 19, 753-754.

 

Emery, N. J. & Clayton, N. S. (2016). An avian perspective on simulating other minds. Learning and Behaviour 44, 203-204.

 

Greggor, A. L., McIvor, G., Clayton, N. S. & Thornton, J. A. N. (2016). Contageous risk taking: social information and context influence wild jackdaws’ responses to novelty and risk. Scientific Reports 6, 27764.

 

Clayton, N. S. (2016). Animal acumen. Science 352, 525.

 

Hoffman, M. M., Cheke, L. G. & Clayton, N. S. (2016). Western scrub-jays (Aphelocoma californica) solve multiple-string problems by the spatial relation of string and reward. Animal Cognition 19, 1103-1114

 

Ostojić, L., Legg, E. W., Williams, N., Brecht, K. F., Dits, A., Mendl, M. & Clayton. N. S. (2016). Experimenter expectancy bias does not explain Eurasian jays’ performance in a desire-state attribution task. Journal of Comparative Psychology 130, 407-411.

 

Greggor, A. L., Jolles, J., Thornton, J. A. N. & Clayton, N. S. (2016). Seasonal changes in neophobia and amd its consistency in rooks: the effect of novelty type and dominance position. Animal Behaviour 121, 11-20.

 

Clayton, N. S. & Wilkins, C. A. P.  (2016). Big Picture: Art is the process of memory.  The Psychologist 29, 15-16.