When I told a colleague that I was reading an article onfish cognition, her first reaction was to laugh. Granted fishare not the first animals that come to mind when thinkingabout animal cognition. However, my colleague’s skepti-cism may reflect more a lack of information in the litera-ture regarding fish cognition than a true assessment of thecognitive abilities of fish. Indeed, Bshary et al.’s (2002)thought-provoking article is filled with observations andexperiments suggesting that fish cognition is an enterpriseworth pursuing. Bshary et al. also proposed three ways toadvance the study of fish cognitive abilities: (1) specifythe ecological factors that select for certain cognitivemechanisms, (2) map the cognitive mechanisms with theircorresponding neural substrate, and (3) find decision rulesin fish to derive null hypotheses for how primates maketheir decisions. I find the first two proposals particularlygood guiding principles for future research. I am less en-thusiastic about the third proposal and I outline my reser-vations below.

Finding a common metric to measure cognitive skillsacross a broad range of species has been one of the holygrails of comparative psychology. Various paradigms,most notably those measuring memory skills or learningability, have been used to compare a variety of species(even to extrapolate between species) in standardized testsituations (e.g., lever pressing in an operant chamber). Inone of the most cited studies, Macphail (1987) concludedthat there were no significant differences across speciesexcept with humans. In other words, all species except hu-mans learn and solve problems in the same way. Althoughthis approach may yield some useful information, it alsohas serious limitations. One limitation is that it places in-dividuals in artificial situations, thus neglecting a species’natural history and depriving individuals of the possibility

to solve problems in “intelligent” ways. For instance, pri-mates master visual discrimination faster when the task ispresented in the context of a foraging situation comparedto a traditional testing situation such as the WGTA (Men-zel and Juno 1982; Menzel 1996). A second limitation isthat species-specific adaptations are sacrificed in compar-isons across species. For example, not acknowledgingsuch adaptations led us to believe that primates outper-formed dolphins in certain types of discrimination learn-ing. However, when dolphins were tested on auditoryrather than visual discrimination, their performance im-proved significantly (Herman 1986). Finally, standardiza-tion does not have much room for the special cognitiveabilities of some species, precisely because they are spe-cial and therefore not suitable for comparisons across anumber of species.

Bshary et al.’s proposal to search decision rules in fishto derive null hypotheses for primates seems grounded onsome of the same assumptions that underlie the use ofstandardized tests to compare and extrapolate across spe-cies. In some sense, fish are viewed as simpler versions ofprimates, and that is why it is justified to extrapolate fromone to the other. Although the search for decision rules ormechanisms shared across species is important, thisshould be carefully balanced with the study of the cogni-tive specializations in those same species. There is nodoubt that there are cognitive mechanisms shared by anumber of species (including fish and primates) but it isalso critical to recognize the importance of species-spe-cific cognitive specializations. Using fish as a null hy-pothesis for primates assumes that fish have not devel-oped any specialized cognitive mechanisms to solve someof the problems encountered in their ecological or socialarenas. Given that they have developed specialized mor-phological adaptations, it is likely that there is room forsome cognitive specializations as well.

I would like to finish this commentary by mentioninganother avenue for research on comparative cognition.Traditionally, comparing cognitive abilities across specieshas entailed studying the cognitive complexity of a be-havior shared by several species. For instance, in the case

Josep Call

A fish-eye lens for comparative studies: broadening the scope of animal cognition

Anim Cogn (2002) 5 :15–16DOI 10.1007/s10071-002-0127-x

Received: 10 January 2002 / Accepted: 14 January 2002 / Published online: 7 February 2002

COMMENTARY

J. Call (✉ )MPI for Evolutionary Anthropology, Inselstrasse 22, 04103 Leipzig, Germanye-mail: call@eva.mpg.de, Tel.: +49-341-9952400, Fax: +49-341-9952119

© Springer-Verlag 2002

of tool use, one can investigate how various species en-code the requirements of a tool, how many steps they canrecall and flexibly execute, or whether individuals planahead their course of action. Yet, this approach of com-paring the same behavior is useless when a species lacksthe behavior in question. One way to bridge the gaps inbehavioral repertoires consists of studying different be-haviors in different species in search of the species’ un-derlying cognitive abilities. For instance, tool use may notbe a suitable behavior to study in fish, but perhaps nestbuilding can uncover some of the same (or different) cog-nitive abilities underlying primate tool use. In a way, thisapproach would be analogous to finding principles in be-havioral ecology that go beyond particular behavioralmanifestations. For instance, foraging involves very dif-ferent behaviors in octopuses, flamingos, and bats, but itstill shares the same basic principles across species. It canbe argued that bypassing specific behaviors in search ofcommon principles is what the standardized approach(e.g., Macphail 1987) accomplishes. The critical differ-ence between this and the standardized approach, how-ever, is that the former investigates cognition in the con-

text in which it evolved rather than in an artificial settingthat imposes important procedural limitations.

In conclusion, research on fish promises to broaden ourscope of animal cognition in various ways. Not only arethere new species and novel problems to be investigated,but such research also forces us to find new ways of mak-ing possible comparisons across distant taxa.

References

Bshary R, Wickler W, Fricke H (2002) Fish cognition: a primateeye’s view. Anim Cogn 5. DOI 10.1007/s1007100101165

Herman LM (1986) Cognition and language competencies of bot-tlenosed dolphins. In: Schusterman RJ, Thomas JA, Wood FG(eds) Dolphin cognition and behavior: a comparative approach.Erlbaum, Hillsdale, N.J., pp 221–252

Macphail EM (1987) The comparative psychology of intelligence.Behav Brain Sci 10:645–695

Menzel CR (1996) Spontaneous use of matching visual cues dur-ing foraging by long-tailed macaques (Macaca fascicularis). J Comp Psychol 110:370–376

Menzel EW, Juno C (1982) Marmosets (Saguinus fuscicollis): arelearning sets learned? Science 217:750–752

16