page_title: Animal cognition
section_title: Cognitive bias
hierarchical_section_title: Animal cognition / Research questions / Cognitive bias
caption_attribution_description: English: A glass of water, demonstrating the eternal conundrum of whether the glass is half full or half empty.
context_page_description: Animal cognition encompasses the mental capacities of non-human animals. The study of animal conditioning and learning used in this field was developed from comparative psychology. It has also been strongly influenced by research in ethology, behavioral ecology, and evolutionary psychology; the alternative name cognitive ethology is sometimes used. Many behaviors associated with the term animal intelligence are also subsumed within animal cognition.
  Researchers have examined animal cognition in mammals, birds, reptiles, fish and invertebrates.
context_section_description: A cognitive bias refers to a systematic pattern of deviation from norm or rationality in judgment, whereby inferences about other individuals or situations may be drawn in an illogical fashion.
  Cognitive bias is sometimes illustrated by using answers to the question "Is the glass half empty or half full?". Choosing "half empty" is supposed to indicate pessimism whereas choosing "half full" indicates optimism. To test this in animals, an individual is trained to anticipate that stimulus A, e.g. a 100 Hz tone, precedes a positive event, e.g. highly desired food is delivered when a lever is pressed by the animal.  The same individual is trained to anticipate that stimulus B, e.g. a 900 Hz tone, precedes a negative event, e.g. bland food is delivered when the animal presses a lever. The animal is then tested by being given an intermediate stimulus C, e.g. a 500 Hz tone, and observing whether the animal presses the lever associated with the positive or negative reward. This has been suggested to indicate whether the animal is in a positive or negative mood.
  In a study that used this approach, rats that were playfully tickled responded differently than rats that were simply handled. The rats that had been tickled were more optimistic than the handled rats. The authors suggested that they had demonstrated "...for the first time a link between the directly measured positive affective state and decision making under uncertainty in an animal model".
  There is some evidence for cognitive bias in a number of species, including rats, dogs, rhesus macaques, sheep, chicks, starlings and honeybees.
caption: Is the glass half empty or half full?
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