Current bio - June 2018

Already discussed in an earlier email chain, Eckert, Rokoczy, Call, Herrmann, & Hanus (2018) published a paper in this month’s issue of Current Bio about chimpanzees considering humans’ psychological states when making statistical inferences. In three experiments there were always two transparent jars: one contained a large proportion of a favorable food to a less favorable food (i.e. 200 peanuts to 20 carrots) and the other contained a large proportion of a less favorable food to a favorable food (200 carrots to 20 peanuts). When drawing randomly, the chimps picked from the experimenter that had a large amount of favorable foods more often. However, the two experimenters then began drawing into the jars while looking and were biased in their choices – the experimenter with the jar of mostly peanuts would always pick a carrot and vice versa. Now the chimps chose from the experimenter that had a jar of mostly carrots but a “preference” for peanuts. They also included a third experiment in which one experimenter drew randomly from the highly favorable jar and one experimenter drew with her “bias” for the highly favorable reward. Then when drawing from jars that were equal in ratio favorable to nonfavorable, the chimps continued to choose more often from the experimenter that was looking into the jar and picking the favorable reward. The results are definitely interesting, but its still up for debate as to whether this is chimps making choices based on human psychological states or something less complex like: ‘did the human look or not’?

Article: https://www.cell.com/current-biology/fulltext/S0960-9822(18)30549-9?dgcid=raven_jbs_etoc_email

Dispatch article: https://www.cell.com/current-biology/fulltext/S0960-9822(18)30620-1?dgcid=raven_jbs_etoc_email

Also, one other paper that might be interesting to some: a recent paper by Jiang et al provides evidence that macaque monkeys can “break the syntax” barrier – produce spatial sequences that represent more complex grammar. Monkeys produced sequences by pressing a touchscreen, generated according to “instructed grammars” – a mirror grammar (ABC --> CBA) and a repeat grammar (ABC --> ABC), and they produced these in different spatial arrays, at different sequence lengths, and on arrays at different spatial locations. The monkeys were also able to produce not just the second half, but the full sequence as well (ABCCBA), which demonstrates that they are producing a complete center-embedded sequence. Finally, one monkey was trained to complete a sequence given just one position (A --> BCCBA). The authors claim that this study goes beyond previous studies that show sequence learning using strategies such as chunking, algebraic patterns, and ordinality because it also includes production of a complete sequence, generalization to novel arrays, lengths, and locations. I’d be interested to hear what others think about this one, because I’m still not completely sold on how this is completely indicative of complex grammar/computational strategies rather than something more memory related, which they mention at the end. I still think the results and are really cool and interesting, but this is not an area I am an super well-versed in either.

Article: https://www.cell.com/current-biology/fulltext/S0960-9822(18)30519-0?dgcid=raven_jbs_etoc_email

Dispatch article: https://www.cell.com/current-biology/fulltext/S0960-9822(18)30559-1?dgcid=raven_jbs_etoc_email