International Journal of Comparative Psychology

Hobhouse viewed comparative psychology as playing a key role in his politically liberal, social-ethical worldview. The main feature of evolving mind was the increased capacity for democratic self-direction. Political reaction, identified with imperialism, attempts ideologically to obscure this fact, and thus to impede social progress. Its instruments are philosophical idealism and pseudo-scientific biologism or Social Darwinism. Comparative psychology, conceived as an essentially human psychology, could counteract this reactionary ideology with genuine scientific knowledge of present human capacity and future potential. These can only be revealed by a correct scientific approach, which, Hobhouse maintained, had to be evolutionary and comparative.

Callithrix jacchus (common marmoset) young receive care from mothers and fathers during early stages of development. In order to evaluate the compensatory care given by mothers when fathers were not giving their usual care, three families of marmosets, in which the fathers evidenced low levels of care from the time of the birth of the young, and two families in which the level of paternal care giving was normal were studied. In two of the low care families, and one of the normal families, the father was removed at 15 days after birth; in the other two families the fathers were removed at 30 days after birth. Data as to duration of care giving by the mother, care giving by the father, and contact between the two offspring (typically the common marmoset gives birth to twins) were recorded from the time of birth through two days after separation. Although the mothers compensated for the low levels of care given by the fathers, the total amount of time spent in care giving did not differ from that of the normal families, in those cases where separation took place at 15 days. In the case of the 30 day separation families, the total time of care giving in the lowcare family was lower than that of the normal family. Contact time between twins also differed between the 15 and 30 day separation families. The results indicate that compensatory care giving can be induced in the common marmoset.

Available data on learning capabilities in immature rodents are briefly summarized and some new findings on early learning in mice are presented. We omit the comparatively small number of works concerning precocial species of rodents, that is, guinea pigs and spiny mice. In a comparison we have already made (D'Udine and Alleva, 1983) we found that rodent species characterized as precocial types appeared to be affected in a dramatic way by environmental factors during postnatal development, as shown by profound modification of their adult behavioral patterns. Since the aim of our contribution is to review the methodological paradigms used to assess early learning capabilities in rodents, we shall focus here on the Norway rat and the house mouse, because they are the only species for which evidence has progressively been built up through the use of different tests.

Context learning was studied in the Red Opossum, the marsupial, Lutreolina crassicaudata . In Experiment 1 the animals received four trials per day in two different boxes (contexts): X and Y. Half of the animals received periodic deliveries of a sugar solution ( + ) in one box (X+), but not in the other (Y-); the rest received the opposite training (X-), (Y+). Several behavioral categories were recorded during the final trial in each context. Animals approached the feeder significantly more in the positive context. Experiment 2 was designed to determine the extent to which the number of trials per day affected acquisition. Two groups of animals received differential training with either four or one trial per day. No differences between groups were observed, although in both of them, approach to the feeder was significantly higher in the positive context. The results are discussed in relation to both the role of practice distribution on learning in marsupials, and their potential value of this species for the study of learning processes.

E. Tobar Editor Historical Persceptives and the International Status of Comparative Psychology