Michael Colombo

Our tendency towards rich interpretations of behaviour is common. Pigeons, however, can solve the same complicated tasks that are solved by primates, and often do so in a manner indistinguishable from primates. If we richly interpret human behaviour, or primate behaviour in general, yet find the exact same signatures of that behaviour in pigeons, we should question whether our rich interpretation is warranted. By understanding how different animals solve complex tasks we can gain a better insight into how humans may be solving those same tasks and potentially avoid the theoretical pitfalls of rich interpretations. We frequently richly interpret human or primate behaviour, yet find the exact same signatures of that behaviour in pigeons. This Comment argues that understanding how different animals solve complex tasks gives us better insight into how humans may be solving those same tasks and potentially avoid the theoretical pitfalls of rich interpretations.

In 1985 Macphail proposed his Null Hypothesis that there were no qualitative differences in intelligence across vertebrate species. A recent review of the literature has found overwhelming support for his view. Studies also suggest that, with respect to cognition and the neural mechanisms that support it, the Null Hypothesis should be extended to invertebrates. We suggest, on the same premise, that the Null Hypothesis should be extended to pain sentience in invertebrates. Although few studies have been conducted, behavioural and neural evidence for pain sentience has been found in various representative invertebrate species.

Editorial: The Comparative Psychology of Intelligence: Macphail Revisited

We examined the role of the avian hippocampus and area parahippocampalis in serial‐order behavior and a variety of other tasks known to be sensitive to hippocampal damage in mammals. Damage to the hippocampus and area parahippocampalis caused impairments in autoshaping and performance on an analogue of a radial‐arm maze task, but had no effect on acquisition of 2‐item, 3‐item, and 4‐item serial‐order lists. Additionally, the lesions had no effect on the retention of 3‐items lists, or on the ability to perform novel derived lists composed of elements from lists they had previously learned. The impairments in autoshaping and spatial behavior are consistent with the findings in mammals. The absence of impairments on the serial‐order task may also be consistent once one considers that damage to the hippocampus in mammals seems to affect more internally‐organized rather than externally‐organized serial‐order tasks. Together, the findings support the view that the avian hippocampal complex serves a function very similar to the mammalian hippocampus, a finding that is interesting given that the architecture of the avian hippocampus differs dramatically from that of the mammalian hippocampus.

We review evidence for Macphail’s (1982, 1985, 1987) Null Hypothesis, that nonhumans animals do not differ either qualitatively or quantitatively in their cognitive capacities. Our review supports the Null Hypothesis in so much as there are no qualitative differences among nonhuman vertebrate animals, and any observed differences along the qualitative dimension can be attributed to failures to account for contextual variables. We argue species do differ quantitatively, however, and that the main difference in “intelligence” among animals lies in the degree to which one must account for contextual variables.

Neurons in the pigeon nidopallium caudolaterale (NCL) are important for the maintenance of information across delays as long as 3 s. In the current study, we recorded neural activity from the avian NCL of 3 birds trained on a working memory task with three different delay lengths intermixed within a session. We found that when the birds are unable to predict the upcoming delay length there is no evidence that NCL cells engage in temporal coding. Furthermore, delay activity did not differ between correct and incorrect trials. Both findings have implications for the function of delay activity and its role in supporting working memory. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

We recorded from single neurons in two areas of the pigeon brain while birds were required to peck a stimulus indicating either a high effort task or a low effort task would follow. Upon completion of the task the birds received the same reward. We found that activity in the nidopallium caudolaterale, an area equivalent to the mammalian prefrontal cortex, was modulated by the value of the reward that would be received based on how much effort was required to obtain it. Value coding was most prominent during the presentation of the stimulus indicating a high or low effort task, and in the delay period immediately prior to carrying out the effort task. In contrast, activity in the corticoidea dorsolateralis was not modulated by value, however, population firing patterns suggest that it may be involved in associating actions with outcomes. Our findings support the view that activity in the nidopallium caudolaterale reflects value of reward as a function of effort discounting and as such may serve functions similar to the mammalian anterior cingulate cortex.