The Relation Between Eliciting Stimulus Strength and Habituation of the Threat Display in Male Siamese Fighting Fish, Betta Splendens

Abstract

AbstractThe threat display of the male Siamese fighting fish (Betta spiendens) is a highly integrated phenomenon, involving approach, extension of the gill covers (opcrculae) and brachiostegal membranes, erection of the medial fins, intense deepening of body color, orientation movcmcnts, and undulatory movements. Many qualitatively different stimuli are capable of eliciting the complete threat display (e.g., live male Betta, mirror image, two dimensional cut-out). However, the relations between the initial eliciting strength of the threat stimulus and the degree of habituation, retention, and recovery of habituation have not been systematically investigated. These relations are important in an eliciting stimulus and competing response theory of habituation like that of RATNER (1970). To investigate the above relations, 40 adult male Bettas were randomly assigned to four independent groups (n = 10). Each S in a particular group was exposed to one of four different eliciting stimuli for two 40 minute sessions separated by a 24 hour rest period. The four thrcat elicitors were: a live unhabituated, highly responsive male Bettca (Unhab. male); a mirror image (Mirror) ; a livc habituatcd, relatively unrcsponsive male Betta (Hab. male) ; and a two dimensional cut-out of a male Betta in lateral display (Cut-out). During threc ro minute observation periods in each session, five different reliable components of the display were simultaneously recorded: air gulping frequency (AG), gill cover erection frequency (GF), gill cover erection duration (GD), fin erection frequency (FF), and fin erection duration (FD). For all five dependent measures, the Unhab. male stimulus was the strongest elicitor followed by the Mirror, Hab. male and Cut-out stimuli, respectively. Only two of the dependent measures (GD, FD) showed a systematic decrement for all stimulus groups. With respect to both of these measures, initial eliciting stimulus strength (response level during the first 10 minute observation) was positively related to absolute response decrement, and proportion of recovery of habituation. Initial eliciting stimulus strength was inversely related to the proportion of decrement across sessions, and the proporton of retention of habituation over a 24 hour period. Four of the threat components (GF, GD, FF, FD) were highly positively related. AG was shown not to be an integral component of the display, itself. The data provided support for portions of an eliciting stimulus and competing response theory of habituation.