Behavioural demand functions of caged laboratory mice for additional space
Publication Type: |
Journal Article |
Year of Publication: |
1997 |
Authors: |
C. M. Sherwin, C. J. Nicol |
Publication/Journal: |
Animal Behaviour |
Keywords: |
behavioral demand function, mice, space |
ISBN: |
0003-3472 |
Abstract:
The importance of a commodity, as perceived by animals, can be determined by measuring the amount of work animals are prepared to perform to gain access to that commodity. In the present study, this method is extended to establish how animals perceive the importance of increasing amounts of one commodity, that is, additional space. The behavioural demand functions of caged laboratory mice, Mus musculus, for additional space ranging from 196 cm2 to 1600 cm2on fixed-ratio schedules ranging from 5 to 80 switch operations were determined. At all fixed-ratio values, the mice worked economically and gained access to additional space on several occasions within each 1-h observation session. The amount of access gained decreased as the work required increased, but the slope of the function (-0.347) was sufficiently shallow to indicate that additional space was regarded by the mice as a highly important commodity. The frequency of visits and the time spent in the additional space were significantly different between the sizes of additional space offered, but unexpectedly, these differences were small. In addition, the elasticity coefficients were not significantly different between the sizes of additional space. The absence of large differences in response to disparate sizes of additional space may indicate that the mice may have (1) been motivated to escape their home-cage, (2) been motivated to search for unavailable resources, or (3) perceive the different amounts of additional space as nearly equally (non-)rewarding. Time of day had a significant effect on the responses of the mice in that towards the end of the active phase, the additional space was visited less frequently and for shorter periods indicating a temporally based change in motivational status or efficiency of behaviour. It is argued that these results support previous evidence that laboratory mice are highly motivated to explore and subsequently monitor areas made accessible to them, regardless of size and, to some extent, content.