Measuring cognition will be difficult but worth it: a response to comments on Rowe and Healy

Editor-in-Chief: Leigh Simmons 0 School of Biology, University of St Andrews , St Andrews, KY16 9TH , UK 1 Centre for Behaviour and Evolution, Institute of Neuroscience, Newcastle University , Henry Wellcome Building, Framlington Place, Newcastle upon Tyne, NE2 4HH , UK Re Fe Re Nces - In our review (Rowe and Healy 2014), we argued that taking too literally the approaches from the experimental psychology literature to measure cognitive abilities in individuals is fraught with problems. It is cheering to see that at least some others agree with this view (Barrett 2014; ten Cate 2014). For the reasons we outlined in that review we continue, however, to be wary of the interpretation of data produced from artificial tasks (Quinn et al. 2014), batteries of tasks on the same individuals (Thornton 2014; Thornton etal. 2014) and psychometric testing (Klm 2014; Thornton 2014; Thornton etal. 2014). For example, animals will bring their experience to bear on their performance in novel artificial tasks (Quinn etal. 2014), and psychometric tests will reflect an animals sensory and motor skills as well as its cognitive capabilities (Nachev and Winter 2012). We are more disappointed to see that another of our messages seems to have been missed, so we will reiterate that we think behavioral ecologists bring a different perspective and an invaluable new approach by addressing questions concerning the adaptive nature of cognition. While the experimental psychologist sweeps aside individual variation in task performance due to their focus on general mechanisms and principles, the behavioral ecologist trained in how natural selection optimizes in the face of trade-offs seeks to understand the causes and consequences of that variation, both inter- and intraspecific. Importantly, based on a deep understanding of an animals or species ecology, the behavioral ecologist can bring the power of hypothesis testing to bear on questions that address the role that cognition might play in that animals survival and/or reproductive success. Here we would also suggest that the plan to use a standard test or a battery of tests misses the point: optimization means that cognitive abilities will themselves be traded off against other capabilities and Rambo will beat Einstein some of thetime. Testing more species (Klm 2014) and remarkable species (Thornton 2014) may, indeed, give some fascinating insights into what different species can do. Cognitive taxonomy, or the natural history of cognition, is a useful starting point for identifying variation in cognition found across species. We would suggest, however, that one might choose ones remarkable species with some care, with a view to both the biological and logistic value of the choice. For example, the knowledge that some birds store food and other, closely related, species do not, lead to work addressing the role that spatial memory, and the hippocampus, play in that behavioral variation (e.g., Biegler etal. 2001). Similarly, if one wished to determine the adaptive role that cognition plays in female choice, then the choice of species would not be a food storer but one in which females vary in the degree to which they exercise mate choice. Here a female bowerbird or a peahen might be the animal of interest. We urge researchers not just to measure cognitive abilities in their study species because they feel its timely. Hypothesis-driven science is what behavioral ecologists are good at and playing to that strength surely leads to more robust advances in understanding how selection acts on cognitive abilities. Finally, we would like to reiterate that we did not intend to dissuade anyone from investigating variation in cognitive abilities (Quinn etal. 2014). This is a misunderstanding we want to correct. We do want to see such investigations (and the more the merrier). But we emphasize again that researchers need to ensure that they can identify the relevant cognitive trait(s). Unless we can robustly do that, we suggest our own sticking plaster solution, which is to encourage researchers to recognize the fact that an animals performance in their cognitive tasks does not necessarily depend upon its cognitive ability. Barrett L. 2014. What counts as (non) cognitive? A comment on Rowe and Healy. Behav Ecol. 25:12931294. Biegler R, McGregor A, Krebs JR, Healy SD. 2001. A larger hippocampus is associated with longer-lasting spatial memory. Proc Natl Acad Sci U S A. 98:69416944. Klm N. 2014. Measuring variation in cognition can be done, but it requires hard empirical work: a comment on Rowe and Healy. Behav Ecol. 25:12961297. Quinn JL, Cole EF, Morand-Ferron J. 2014. Studying microevolutionary processes in cognitive traits: a comment on Rowe and Healy. Behav Ecol. 25:12971298. Nachev V, Winter Y. 2012. The psychophysics of uneconomical choice: non-linear reward evaluation by a nectar feeder. Anim Cogn. 15:393400. Rowe C, Healy SD. 2014. Measuring variation in cognition. Behav Ecol. 25:12871292. ten Cate C. 2014. Towards fruitful interactions between behavioral ecology and cognitive science: a comment on Rowe and Healy. Behav Ecol. 25:12951296. Thornton A. 2014. How and why are some species so smart? A comment on Rowe and Healy. Behav Ecol. 25:12941295. Thornton A, Isden J, Madden JR. 2014. Toward wild psychometrics: linking individual cognitive differences to fitness. Behav Ecol. 25:12991301. (...truncated)