Lea, S. E., Wills, A. J., Leaver, L. A., Ryan, C. M., Bryant, C. M., & Millar, L. (2009). A comparative analysis of the categorization of multidimensional stimuli: II. Strategic information search in humans (Homo sapiens) but not in pigeons (Columba livia). Journal of Comparative Psychology, 123(4), 406. doi:10.1037/a0016851
[Abstract]Pigeons and undergraduates learned conditional discriminations involving multiple spatially separated stimulus dimensions. Under some conditions, the dimensions were made available sequentially. In 3 experiments, the dimensions were all perfectly valid predictors of the response that would be reinforced and mutually redundant; in 2 others, they varied in validity. In tests with stimuli in which 1 of the 3 dimensions took an anomalous value, most but not all individuals of both species categorized them in terms of single dimensions. When information was delivered as a function of the passage of time, some students, but no pigeons, waited for the most useful information, especially when the cues differed in objective validity. When the subjects could control information delivery, both species obtained information selectively. When cue validities varied, almost all students tended to choose the most valid cues, and when all cues were valid, some chose the cues by which they classified test stimuli. Only a few pigeons chose the most useful information in either situation. Despite their tendency to unidimensional categorization, the pigeons showed no evidence of rule-governed behavior, but students followed a simple “take-the-best” rule.
[Citing Place (1988b)]  
Citing Place (1988b) in context (citations start with an asterisk *):
* An important difference between human and animal cognition appears to be that humans are much more able than other animals to govern their behavior by rules. Some psychologists, notably Skinner (1969, chap. 6), have sought to reserve the term rule-governed for behavior that is under the control of explicit verbal statements, and this usage is widespread in the field of behavior analysis (e.g., Hayes & Hayes, 1992; Place, 1988). On this view, it becomes trivially true that only human behavior (and perhaps the behavior of language-trained individuals of other taxa) can be rule-governed. However many cognitive psychologists have found it useful to have a less language-centered definition of “rule governed.” For example, theorists of categorization have often assumed that the use of a single dimension to sort multidimensional stimuli is diagnostic for the use of analytic processing, as compared with a nonanalytic process that would result in classification on the basis of overall similarity (e.g., Smith & Kemler Nelson, 1984).