Matching based on biological categories in Orangutans (Pongo abelii) and a Gorilla (Gorilla gorilla gorilla)

Following a series of experiments in which six orangutans and one gorilla discriminated photographs of different animal species in a two-choice touch screen procedure, Vonk & MacDonald (2002) and Vonk & MacDonald (2004) concluded that orangutans, but not the gorilla, seemed to learn intermediate level category discriminations, such as primates versus non-primates, more rapidly than they learned concrete level discriminations, such as orangutans versus humans. In the current experiments, four of the same orangutans and the gorilla were presented with delayed matching-to-sample tasks in which they were rewarded for matching photos of different members of the same primate species; golden lion tamarins, Japanese macaques, and proboscis monkeys, or family; gibbons, lemurs (Experiment 1), and subsequently for matching photos of different species within the following classes: birds, reptiles, insects, mammals, and fish (Experiment 2). Members of both Great Ape species were rapidly able to match the photos at levels above chance. Orangutans matched images from both category levels spontaneously whereas the gorilla showed effects of learning to match intermediate level categories. The results show that biological knowledge is not necessary to form natural categories at both concrete and intermediate levels

Attentional, instructional, and depth effects on retrieval estimates

Much evidence has been presented in support of the view that deeper levels of processing (DOP) during encoding lead to substantial increases in explicit memory performance. The effects of DOP on implicit memory performance have been much more controversial. We attempted to find evidence to support the idea that deeper processing may influence automatic retrieval processes and that contradictory findings from the process dissociation procedure (PDP) may have resulted from the underestimation of automatic retrieval. This underestimation would result when automatic (A) and conscious retrieval (C) processes are positively correlated rather than independent as the PDP model suggests. We found that the underestimation of A was greater for words encoded semantically than for words encoded nonsemantically as expected, thus explaining the paradoxical finding that A was greater for the nonsemantic items. Therefore, previous findings of invariance in A after depth manipulations may have been artifacts of a bias in the PDP procedure. Our findings support the hypothesis that subjects typically engage in generate recognize retrieval strategies, causing a violation of the independence assumption and leading to a facilatory relationship between A and C

Researchers, not dogs, lack control in an experiment on jealousy

Cook and colleagues (2018) have developed a clever method to measure fMRI in awake dogs in response to a number of interesting stimuli. As a result, they are able to determine neural correlates of observable behavior. They report that dogs may experience something akin to jealousy because they show greater amygdala activation in response to food being given to a fake dog versus food being placed in a bucket. However, several critical controls are missing which prevent the authors from being able to speak of jealousy

Octopi-ing a unique niche in comparative psychology

Mather’s work has been fundamental in informing scientists of the relatively mysterious behavior and cognition of an understudied group of animals – the cephalopods. This work helps to fill a gap in the comparative literature that has historically sought evidence for complex behavior only in species that are closely related to humans or share important ecological features such as social complexity

Unique in degree not kindness

Humans are certainly unique among living species. This is evident in the transformation of human environments and its resulting impact on other animals. However, many of the traits unique to humans are costly as well as adaptive and should certainly not be used to elevate their status above that of other species

Pulling the wool from our eyes

Marino & Merskin review evidence of the complexity of sheep cognition, concluding that researchers ought to feel sheepish about misrepresenting ovine cognitive capacities. However, the failure to situate the data in critical context risks pulling the wool over readers’ eyes

What can research on nonhumans tell us about human dissonance?

Zentall’s thoughtful review of the literature on cognitive dissonance in nonhumans helps to highlight the common finding that similar outcomes in humans and nonhumans can be attributed to different underlying mechanisms. I advocate a more fully comparative approach to the underlying mechanisms, avoiding the assumption of shared processes in humans and nonhumans

Researchers, not dogs, lack control in an experiment on jealousy

Cook and colleagues (2018) have developed a clever method to measure fMRI in awake dogs in response to a number of interesting stimuli. As a result, they are able to determine neural correlates of observable behavior. They report that dogs may experience something akin to jealousy because they show greater amygdala activation in response to food being given to a fake dog versus food being placed in a bucket. However, several critical controls are missing which prevent the authors from being able to speak of jealousy

Peer Influence on Conformity and Confidence in a Perceptual Judgment Task

© 2020 by authors. Undergraduate college students were presented with two arrays of dots varying in numerosity on a computer screen and asked to indicate if the arrays differed in number. They also rated their level of confidence in their responses. Trials varied in difficulty based on the size of the arrays. On half of the trials, participants were shown the ostensible responses of confederates to test the effect of peer influence on numerosity judgments and participant confidence. On the other half of the trials, participants received no information about the responses of the confederates to provide a measure of baseline performance. Higher levels of conformity were observed for the difficult trials, on which participants were both less accurate and less confident. However, confidence ratings were influenced by peer judgments for easy trials but not for difficult trials. These data suggest that task difficulty influences conformity when making perceptual judgments