Avoidance of novel objects by rabbits (Oryctolagus cuniculus L.)

Neophobia (fear of new stimuli) is an important component of mammalian behavioural ecology. In addition, information on neophobia in pest species could be of great significance in targetting control measures and predicting changes in responses to them. Novel objects and an auditory stimulus were presented to individually marked wild rabbits living socially in clumped warrens in southern British farmland. Avoidance of stimuli was measured by scan sampling of rabbits’ locations, in replicated experiments. Rabbits avoided a variety of novel objects by staying below ground, and by changing their activity ranges. Responses to different stimuli were correlated within individuals. There were non-significant differences in the degree of avoidance elicited by novel visual stimuli. The most important factors in avoidance were distance from the stimulus, number of previous presentations, and rabbit identity. Individual characteristics, including sex, social rank, and trappability, were less important determinants of neophobia, although dominant females were significantly more neophobic than were non-dominant ones. Only one or two presentations were required for attenuation of avoidance, so novel objects would be of limited application to crop protection. However, equipment used for delivering control measures should also quickly become accepted by rabbits. The measured avoidance and its attenuation indicate that rabbits assessed and responded to their surroundings with high precision, with significant individual variation consistent over stimuli.

The Contractile Properties of a Crab Respiratory Muscle

1. Contraction of scaphognathite muscle L2B of the green crab Carcinus maenas is strongly dependent on stimulus number and frequency. Single, supramaximal stimuli evoke little or no tension. When stimulated with shocks in either short bursts (10 stimuli in 0.5s or less) or long bursts (5 s of stimulation), the isometric tension from the muscle increases with increasing stimulus frequency to a maximum at about 150 Hz at 15°C, beyond which tension declines with further increase in stimulus frequency. 2. There can be facilitation of both contraction and relaxation between short bursts of stimuli. Facilitation of contraction is seen as increasing tension on successive bursts of a series, even when the interburst interval is long enough for relaxation to be completed during the interval. Interburst facilitation lasts at least 10 s. Facilitation of relaxation is seen as progressively faster relaxation from burst to burst of a series, and relaxation to lower tension levels when the interburst interval is so short that relaxation is incomplete in the interburst interval. 3. Maximum isometric tension occurs at muscle lengths slightly longer than the longest muscle length reached in vivo. Tension declines rapidly with changes in muscle length away from the optimum length. The maximum isometric tension was about 12 N cm−2. 4. The maximum shortening velocity of a tetanically activated muscle was determined as 1.9 lengthss−1 (Ls−1) by extrapolation of force-velocity curves to zero force and 3.3 Ls−1 by slack test measurements. 5. The scaphognathite muscle would be classified as a slow or tonic muscle on the basis of its requirements for multiple stimulation to reach full activation, and as a moderately fast muscle on the basis of its force-velocity properties.

Neurobiology of the Gorgonian Coelenterates, Muricea Californica And Lophogorgia Chilensis: I. Behavioural Physiology

1. Electrical or mechanical stimulation of Muricea californica or Lophogorgia chilensis colonies resulted in withdrawal of polyps in the immediate vicinity of the stimulation point. Additional stimulation did not result in further spread of polyp retraction. 2. Electrical activity was recorded from a colonial conduction system not restricted to the area of polyp withdrawal. Conduction velocity in this conduction system decreased with increasing stimulus number and distance from the stimulation point. 3. Polyp withdrawal in Muricea occurred concomitantly with a burst of facilitating electrical impulses. The withdrawal burst was always preceded by impulses of the colonial conduction system. 4. The pattern of colonial behaviour in gorgonians depends upon the conduction properties of the colonial conduction system, the conduction system(s) of each individual polyp, and the pathways connecting the two. 5. Polyp tentacles bend to the oral disk when presented with liver extract. A burst of electrical impulses was recorded from Muricea polyps during chemical stimulation. These bursts exhibited apparent adaptation and presumably represent muscle potentials resulting from chemoreceptor activation.

Conditioning of Affect to a Neutral Stimulus: Number of Trials

A conditioning model can be used to explain the evaluation process and interpersonal attraction. Since number of trials is an important variable in conditioning research, it was predicted that evaluation of a neutral stimulus should become progressively more positive with trials when paired with positive reinforcers and it should become more negative when paired with negative reinforcers. Subjects in the experimental groups were presented with 15 paired presentations of a geometric figure and attitudes that were either similar or dissimilar. Subjects in the control groups were presented with attitudes without the figure. Evaluations of the figure were made before and after the presentations. Evaluations became more negative over trials when the figure was paired with dissimilar attitudes, but there was no change when it was paired with similar attitudes (Groups × Trials interaction, p < .001). There was no change over trials in the control groups. Differential awareness among the groups was not significant. The results demonstrate the utility of the conditioning model.