Thesis (Ph.D.) - University of Michigan, 1969
Bindra (1961) has suggested that general activity in the rat studied through the use of exclusive and exhaustive behavior coding categories based on the motor movements and body configurations of the animal. The present study attempts to implement this suggestion, improving Bindra's behavior sampling procedure by using continuous (to the nearest 1 sec.) coding, a finer level of categorization, and a large number of repeated exposures to the same environment and to stimulus change. Eight hooded rats were observed during 60 daily 10 min. ses= sions in a modified small animal test chamber. Behavior was coded into 10 categories within three classes: locomotor, pointing, selective, rearing, and nudging exploration; face and paw, dorsal, ventral and hind foot grooming; and pausing. These categories proved reliably distinguishable and were observed under five stimulus conditions: standard empty cage, scent, visual, auditory, and holes in the wall. Each of these conditions was present over at least five continuous days, and the standard condition was repeated twice after its initial presentation period of 20 days. The results supported the generalization that exploration decreases with exposure to a particular stimulus condition, both within and across exposure periods. This decrease appears to occur in two phases, a rapid initial decline, followed by a very slow decline involving a characteristic repeatable level of responding. This level of responding, at least in the case of the standard condition, could be re-established by reinstating the stimulus conditions. The form of the decline within a single exposure period was similar for most categories, but showed evidence of competition for expression between them. The results did not support a simple stimulus change hypothesis of exploration. The presentation of a new stimulus condition seemed to increase only those categories of exploration which were relevant to an examination of the stimuli. Removing a stimulus condition usually merely returned responding to a level characteristic of the old stimulus conditions. In general, exploration categories showed independent elicitation, low positive sequential dependencies which decreased with time of exposure, and a relatively stereotyped average duration of expression. Exploration seemed to serve three functions capable of relating the animal to a wide variety of stimulus conditions: (a) the expression of caution (b) the acquisition of general information and (c) the acquisition of specific thorough information. These functions were not always cleanly separable. Changes in pausing were usually in the opposite direction to those in exploration. Several kinds of pausing were distinguished (listening, forced, and resting). These observations together with evidence of response competition and sequential independence between pausing and exploration were used to argue that pausing is an actual behavior rather than a place holder necessitated by the coding scheme. Grooming tended to peak near the middle of the exposure period, though face and paw grooming peaked earlier. There was considerable between and within animal variability in grooming, and a strong positive sequential dependency between face and paw, dorsal, and ventral grooming. Evidence was presented for a displacement-conflict theory of grooming, but elements of response competition and inter-category differences in expression indicated the need for more complex models of grooming. Analyses of the first order transitions between behavior classes showed a large degree of sequential independence; the first order transitions between the categories supported the coherence of the behavior classes, except that pointing exploration was more closely associated with pausing than with the other exploration categories. Analyses of the second order transition& between both classes and categories showed a large number of deviations from independence involving the alternating repetition of a behavior (behavior triples of the form, XNX).