JCP - June 2018

New issue of JCP, and some good stuff in here. I am writing these up in summary forms that will make it easy for me to then also use them for SBNCP social media sites, which is something we want this Wiki to also help with. To do that, I will lead with a paragraph that is social-media ready, then get personal with my comments to our group alone. Off we go!

New research with an African Grey parrot shows that they may engage in probabilistic reasoning. Clements et al. worked with a parrot previously trained to use English labels referentially to identify objects. The parrot observed a human researcher deposit 2 different types of items in a 3:1 ratio (e.g., 3 corks and 1 piece of paper) into an opaque bucket. One item was then randomly withdrawn while hidden from the parrot’s view. When asked to identify the still-hidden object, the parrot’s vocal responses tracked this 3:1 ratio over a large number of trials. The authors argue that this shows that probabilistic reasoning is not limited to humans, nonhuman primates, or even mammals.

Clements, K. A., Gray, S. L., Gross, B., & Pepperberg, I. M. (2018). Initial evidence for probabilistic reasoning in a grey parrot (Psittacus erithacus). *Journal of Comparative Psychology*.

A new paper in Journal of Comparative Psychology indicates that rats may communicate needs to each other in ways that facilitates cooperation. Manon K. Schweinfurth and Michael Taborsky studied whether altruistic acts (in a Prisoner's Dilemma game) were conditional on the communication of the recipient’s need. They used a 2-player mutual food-provisioning task, prospective recipients show a behavioral cascade reflecting increasing intensity First, prospective receivers reach out for the food themselves, then they emit ultrasonic calls toward their partner, before finally showing noisy attention-grabbing behaviors. Food-deprived individuals communicate need more intensively than satiated ones. In return, donors provide help corresponding to the
intensity of the recipients’ communication. These results suggest that the donors attend to the need of the other players in these types of situations.

Schweinfurth, M. K., & Taborsky, M. (2018). Norway rats (Rattus norvegicus) communicate need, which elicits donation of food. *Journal of Comparative Psychology*.

There is also a commentary on this article, as part of a new thing that JCP is doing to feature one article each issues with some commentary.

An interesting new paper in Journal of Comparative Psychology by Juliane Bräuer and Julia Belger shows that dogs often demonstrate "surprise" when following a scent trail for one type of item but then finding only another type of item. This matches other research showing the same kind of surprise when visual information was mismatched and suggests that dogs represent the items associated with specific smells. There did not seem to be any effect of working dogs versus family dogs in this study in terms of fetching the toys.

Bräuer, J., & Belger, J. (2018). A ball is not a Kong: Odor representation and search behavior in domestic dogs (Canis familiaris) of different education. *Journal of Comparative Psychology*.

In a study by Lauren Howard, Cassandra Festa, and Elizabeth Lonsdorf, capuchins were familiarized to
videos of a social model (a human hand) and a nonsocial model (a mechanical claw) building a simple three-block tower. Then, the test was to look at two towers, one identical and one different. If a social model increases event memory, capuchins should show a stronger novelty preference (looking to the new tower) in the social versus nonsocial condition. This is what they reported. However, see my comments on this one about some questions.

Howard, L. H., Festa, C., & Lonsdorf, E. V. (2018). Through their eyes: The influence of social models on attention and memory in capuchin
 monkeys (Sapajus apella). *Journal of Comparative Psychology*.

Finally, this last group of goofballs wrote an article about monkeys and uncertainty.

A new article in JCP by Smith et al. considers how researchers may be able to observe animals’ strategic cognitive processes more clearly. The researchers asked humans and rhesus macaques to commit to completing spatially extended mazes or to decline completing them through a trial-decline response. The mazes could sometimes be completed successfully, but other times had a constriction that blocked completion. A deliberate, systematic scanning process could pre-evaluate a maze and determine the appropriate response. There was evidence that some humans and some monkeys scanned the mazes, in a way that allowed them to base trial-decline responses on temporally extended evaluation processes.

Smith, J. D., Boomer, J., Church, B. A., Zakrzewski, A. C., Beran, M. J., & Baum, M. L. (2018). I scan, therefore I decline: The time course of difficulty monitoring in humans (Homo sapiens) and macaques (Macaca mulatta). *Journal of Comparative Psychology.*