African grey parrot Griffin outsmarts 21 Harvard undergraduate students and children in a visual memory test
According to the researchers, both the parrot and the human participants were using a feature of their working memories called manipulation to succeed in tasks
What happens when a parrot goes head-to-head with 21 Harvard students in a test that measures a type of visual memory? To put it simply, the parrot outperforms them.
Intelligent behavior is shaped by the abilities to store and manipulate information in visual working memory, say experts. The research team from Harvard University and Johns Hopkins University wanted to understand to what extent are manipulation limits unique to humans versus shared across species. The authors compared how 21 human adults (Harvard undergraduate students) and 21 children in the age group of 6 to 8 years stacked up against an African grey parrot (Psittacus erithacus) named Griffin in a complex version of the classic “Shell Game,” which required mentally updating the locations of objects that swapped places several times.
Griffin, the 22-year-old male Grey parrot, has been the subject of cognitive and communicative studies (such as object permanence, developmental tasks, vocal labeling), since his acquisition from a breeder at 7.5 weeks of age. According to the researchers, the reason these birds do so well on cognitive tests is that even though their brain is the size of a shelled walnut, it is so densely packed with neurons that the density is comparable to that of non-human primates.
In the experiment, small colored woolen pompoms were covered with cups and then shuffled, so participants had to track which object was under which cup. They were then showed a pompom from a separate pile and asked to find the matching color beneath the cups. Griffin used his beak to point. The participants were tested on tracking two, three, and four different-colored pompoms. The position of the cups was swapped zero to four times for each of those combinations. This means by the end of the day, the participants had to keep track of four different-colored pompoms under four cups, which were shuffled four times. Griffin and the Harvard students did 120 trials; the children did 36.
“On some trials, the cups remained stationary (0 swaps), requiring participants to store mental representations of these objects in memory. However, for most trials, pairs of cups swapped positions multiple times (1 to 4 swaps), requiring participants to manipulate their mental representations by updating the color-location information of the moving objects (that is, which pompom went where). After all swaps were complete, participants were shown a target colored pompom and instructed to indicate the cup under which they expected to find the object that matched that color,” says the team in the study published in Scientific Reports. They add, “To ensure that the 6-to-8-year olds remained cooperative and attentive during the experiment, the duration of children’s testing session was shortened by reducing the number of trials per condition and eliminating 4 swap trials (longest in duration) altogether.”
The game tested the brain’s ability to retain the memory of items that are no longer in view and then updating when faced with new information, like a change in location. This cognitive system is otherwise referred to as the visual working memory. The results show that Griffin outperformed the 6- to 8-year-olds across all levels on average. He either matched or beat the Harvard students up to 3 moves in 12 of the 14 of trials.
Griffin's abilities started to decrease only at the end of the day when four pom-poms were shuffled three or four times. “The outcome of this analysis is that across set sizes 2 through 4, and number of swaps from 0 through 4, a Grey parrot, with no training on this task except observing two humans perform 3 trials, performed overall comparably to adults. The one exception to this generalization was that increasing manipulation load at the highest set size led the parrot’s performance to plummet below human adults’, approaching that of 6-to-8-year old children,” write authors.
But what factors could cause the parrot’s accuracy levels to drop? According to the team, these factors may not be related to fundamental cognitive capacities at all. The parrot had been given 3 or 4 trials in this experiment every day for many months, and sometimes, near the end, when he saw the 4-cup set up (before trial onset), he simply refused to engage. This shows that motivation might explain the decline, say authors. There could be other factors at play too, they add. “Taken together, the results of the current study suggest that manipulation ability is not a uniquely human capacity, and that overall comparable signatures of manipulation limits can be found in human adults and at least one Grey parrot. Although we had access to only a single parrot, following generally accepted arguments, we suggest that his reliable performance at a given level represents the potential capacity of the species,” says the team.
What does this bird-brain study tell us about the power of cognition? According to the researchers, both the parrot and the human participants were using a feature of their working memories called manipulation to succeed in these tasks. Not only were they able to remember which pompoms were under which cups once they were out of view, but they were then able to manipulate that information as the cups were shuffled around. The authors say the fact that a parrot performed on-par with human competitors suggests that manipulation is an evolutionarily ancient capability, which may have existed in a common ancestor millions of years ago and it developed over time. Future work is needed to confirm manipulation ability across a wider variety of species, identify when manipulation ability emerged, and understand how or if its capacity changed across evolution, says the team.