Editing Animal cognition (section)

=== Concepts and categories ===
Fundamental but difficult to define, the [[concept]] of "concept" was discussed for hundreds of years by philosophers before it became a focus of psychological study.  Concepts enable humans and animals to organize the world into functional groups; the groups may be composed of perceptually similar objects or events, diverse things that have a common function, relationships such as same versus different,  or relations among relations such as analogies.<ref>{{cite book | vauthors = Smith EE, Medin DL | date = 1981 | title = Categories and Concepts | publisher = Harvard Univ. Press}}</ref> Extensive discussions on these matters together with many references may be found in Shettleworth (2010)<ref name="Shettleworth" />  Wasserman and Zentall (2006)<ref name="Wass" /> and in Zentall ''et al.'' (2008).  The latter is freely available online.<ref name="Zentall">{{cite journal | vauthors = Zentall TR, Wasserman EA, Lazareva OF, Thompson RK, Rattermann MJ | year = 2008 | title = Concept Learning in Animals | journal = Comparative Cognition & Behavior Reviews | volume = 3 | pages = 13–45 | doi = 10.3819/ccbr.2008.30002 | doi-access = free}}</ref>

==== Methods ====
Most work on animal concepts has been done with visual stimuli, which can easily be constructed and presented in great variety, but auditory and other stimuli have been used as well.<ref>{{cite book | vauthors = Dooling RJ, Okanoya K | date = 1995 | chapter = Psychophysical methods for assessing perceptual categories. | veditors = Klump GM, Dooling RJ, Fay RR, Stebbins WC | title = Methods in Comparative Psychoacoustics | pages = 307–318 | location = Basel, Switzerland | publisher = Birkhäuser Verlag}}</ref> Pigeons have been widely used, for they have excellent vision and are readily conditioned to respond to visual targets; other birds and a number of other animals have been studied as well.<ref name="Shettleworth" />
In a typical experiment, a bird or other animal confronts a computer monitor on which a large number of pictures appear one by one, and the subject gets a reward for pecking or touching a picture of a category item and no reward for non-category items. Alternatively, a subject may be offered a choice between two or more pictures.  Many experiments end with the presentation of items never seen before; successful sorting of these items shows that the animal has not simply learned many specific stimulus-response associations. A related method, sometimes used to study relational concepts,  is matching-to-sample. In this task an animal sees one stimulus and then chooses between two or more alternatives, one of which is the same as the first;  the animal is then rewarded for choosing the matching stimulus.<ref name="Shettleworth" /><ref name="Wass" /><ref name="Zentall" />

==== Perceptual categories ====
Perceptual categorization is said to occur when a person or animal responds in a similar way to a range of stimuli that share common features.  For example, a squirrel climbs a tree when it sees Rex, Shep, or Trixie, which suggests that it categorizes all three as something to avoid.  This sorting of instances into groups is crucial to survival.  Among other things, an animal must categorize if it is to apply learning about one object (e.g. Rex bit me) to new instances of that category (dogs may bite).<ref name="Shettleworth" /><ref name="Wass" /><ref name="Zentall" />

==== Natural categories ====
Many animals readily classify objects by perceived differences in form or color.  For example, bees or pigeons quickly learn to choose any red object and reject any green object if red leads to reward and green does not.  Seemingly much more difficult is an animal's ability to categorize natural objects that vary a great deal in color and form even while belonging to the same group. In a classic study, [[Richard J. Herrnstein]] trained pigeons to respond to the presence or absence of human beings in photographs.<ref>{{cite journal | vauthors = Herrnstein RJ, Loveland DH | title = Complex Visual Concept in the Pigeon | journal = Science | volume = 146 | issue = 3643 | pages = 549–51 | date = October 1964 | pmid = 14190250 | doi = 10.1126/science.146.3643.549 | bibcode = 1964Sci...146..549H | s2cid = 11940233}}</ref>  The birds readily learned to peck photos that contained partial or full views of humans and to avoid pecking photos with no human, despite great differences in the form, size, and color of both the humans displayed and in the non-human pictures.  In follow-up studies, pigeons categorized other natural objects (e.g. trees) and after training they were able without reward to sort photos they had not seen before .<ref>{{cite journal | vauthors = Herrnstein RJ | year = 1979 | title = Acquisition, Generalization, and Discrimination Reversal of a Natural Concept | journal = Journal of Experimental Psychology: Animal Behavior Processes | volume = 5 | issue = 2| pages = 116–129 | doi=10.1037/0097-7403.5.2.116| pmid = 528881}}</ref><ref>{{cite journal | vauthors = Bhatt RS, Wasserman EA, Reynolds WF, Knauss KS | title = Conceptual behavior in pigeons: Categorization of both familiar and novel examples from four classes of natural and artificial stimuli. | journal = Journal of Experimental Psychology: Animal Behavior Processes | date = July 1988 | volume = 14 | issue = 3 | pages = 219–234 | doi = 10.1037/0097-7403.14.3.219}}</ref>  Similar work has been done with natural auditory categories, for example, bird songs.<ref>{{cite journal | vauthors = Tu HW, Smith EW, Dooling RJ | title = Acoustic and perceptual categories of vocal elements in the warble song of budgerigars (Melopsittacus undulatus) | journal = Journal of Comparative Psychology | volume = 125 | issue = 4 | pages = 420–30 | date = November 2011 | pmid = 22142040 | pmc = 4497543 | doi = 10.1037/a0024396}}</ref>  Honeybees (''[[Apis mellifera]]'') are able to form concepts of "up" and "down".<ref>{{cite journal | vauthors = Avarguès-Weber A, Dyer AG, Giurfa M | title = Conceptualization of above and below relationships by an insect | journal = Proceedings. Biological Sciences | volume = 278 | issue = 1707 | pages = 898–905 | date = March 2011 | pmid = 21068040 | pmc = 3049051 | doi = 10.1098/rspb.2010.1891}}</ref>

==== Functional or associative categories ====
Perceptually unrelated stimuli may come to be responded to as members of a class if they have a common use or lead to common consequences. An oft-cited study by Vaughan (1988) provides an example.<ref>{{cite journal | vauthors = Vaughan Jr W | year = 1988 | title = Formation of equivalence sets in pigeons | journal = Journal of Experimental Psychology: Animal Behavior Processes | volume = 14 | pages = 36–42 | doi=10.1037/0097-7403.14.1.36}}</ref>  Vaughan divided a large set of unrelated pictures into two arbitrary sets, A and B.  Pigeons got food for pecking at pictures in set A but not for pecks at pictures in set B.  After they had learned this task fairly well, the outcome was reversed: items in set B led to food and items in set A did not. Then the outcome was reversed again, and then again,  and so on. Vaughan found that after 20 or more reversals,  associating a reward with a few pictures in one set caused the birds to respond to the other pictures in that set without further reward as if they were thinking "if these pictures in set A bring food, the others in set A must also bring food."  That is, the birds now categorized the pictures in each set as functionally equivalent. Several other procedures have yielded similar results.<ref name="Shettleworth" /><ref name="Zentall" />

==== Relational or abstract categories ====
When tested in a simple stimulus matching-to-sample task (described above) many animals readily learn specific item combinations, such as "touch red if the sample is red, touch green if the sample is green."  But this does not demonstrate that they distinguish between "same" and "different" as general concepts.  Better evidence is provided if, after training, an animal successfully makes a choice that matches a novel sample that it has never seen before.  Monkeys and chimpanzees do learn to do this, as do pigeons if they are given a great deal of practice with many different stimuli. However,  because the sample is presented first, successful matching might mean that the animal is simply choosing the most recently seen "familiar" item rather than the conceptually "same" item. A number of studies have attempted to distinguish these possibilities, with mixed results.<ref name="Shettleworth" /><ref name="Zentall" />

==== Rule learning ====
The use of rules has sometimes been considered an ability restricted to humans, but a number of experiments have shown evidence of simple rule learning in primates<ref>{{cite journal | vauthors = D'Amato MR, Colombo M | title = Representation of serial order in monkeys (Cebus apella) | journal = Journal of Experimental Psychology: Animal Behavior Processes | volume = 14 | issue = 2 | pages = 131–9 | date = April 1988 | doi = 10.1037/0097-7403.14.2.131 | pmid = 3367099}}</ref> and also in other animals.  Much of the evidence has come from studies of [[sequence learning]] in which the "rule" consists of the order in which a series of events occurs.  Rule use is shown if the animal learns to discriminate different orders of events and transfers this discrimination to new events arranged in the same order. For example,  Murphy ''et al.'' (2008)<ref>{{cite journal | vauthors = Murphy RA, Mondragón E, Murphy VA | title = Rule learning by rats | journal = Science | volume = 319 | issue = 5871 | pages = 1849–51 | date = March 2008 | pmid = 18369151 | doi = 10.1126/science.1151564 | url = http://www.cal-r.org/mondragon/home/Papers/MurphyMondragonMurphy-08.pdf | bibcode = 2008Sci...319.1849M | s2cid = 591112}}</ref> trained rats to discriminate between visual sequences.  For one group ABA and BAB were rewarded, where A="bright light" and B="dim light".  Other stimulus triplets were not rewarded.  The rats learned the visual sequence, although both bright and dim lights were equally associated with reward.  More importantly, in a second experiment with auditory stimuli, rats responded correctly to sequences of novel stimuli that were arranged in the same order as those previously learned.  Similar sequence learning has been demonstrated in birds and other animals as well.<ref>{{cite journal | vauthors = Kundey SM, Strandell B, Mathis H, Rowan JD | year = 2010 | title = Learning of monotonic and nonmonotonic sequences in domesticated horses (''Equus callabus'') and chickens (''Gallus domesticus'') | journal = Learning and Motivation | volume = 14 | issue = 3| pages = 213–223 | doi = 10.1016/j.lmot.2010.04.006}}</ref>