Warmup in avoidance as a function of time since prior training

On avoidance procedures, rats and pigeons typically show warmup effects, characterized by improving performance within sessions and loss of the improvement (“warmup decrement”) between sessions. Between-session losses were examined by varying the time between periods of avoidance training. In one experiment, rats lived fulltime in conditioning chambers while intermission intervals were varied. In a second experiment, the animals lived in home cages between sessions; timeout intervals were introduced at midession, producing recurrence of warmup in the second half-session. In both experiments, the warmup decrements increased substantially as the timeout or intersession intervals were increased from zero to 30 minutes. With intervals of 60 or 120 minutes, the decrements approached or exceeded those obtained with intervals of a day or more. When avoidance was interposed between appetitive sessions, the appetitive responding was disrupted, but this seemed unrelated to the warmup or to the proficiency of avoidance. The warmup in avoidance shares characteristics with transient punishment effects, with the Kamin effect, and with habituation phenomena, but it is premature to assume that they reflect common processes.     

Beyond the relational principle of reinforcement

Behavior under baseline conditions in which the contingency is absent can shed some light on the individual's performance under a schedule, but is insufficient as a basis for prediction of performance. This insufficiency of the baseline data runs counter to a recent formalization of the relational principle of reinforcement (Donahoe, 1977). A more satisfactory predictive model must incorporate not only the baseline level of the instrumental response and that of the contingent response, but also the schedule requirements, the character of each response in relation to the other, and the behavior required in simply switching from each to the other.     

Effects of signals preceding and following shock on baseline responding during a conditioned-suppression procedure

Long-Evans rats were exposed to a succession of conditioned-suppression procedures involving pairings of (1) signal-shock, (2) shock-signal, and (3) a signal-shock-signal sequence in which first and second signals were at first physically identical. Traditional suppression of food-reinforced responding was obtained under the signal-shock arrangement, and exposure to the shock-signal sequence resulted in conditioned enhancement of responding during the signal. The signal-shock-signal condition reliably suppressed responding during the first signal, but produced no differential effect on response rate during the second signal. Baseline responding was least changed from preshock rates under the signal-shock-signal procedure, but baseline rate was considerably reduced under the signal-shock and shock-signal arrangements, the latter yielding most substantial reductions. A second experiment indicated that the magnitude and direction of changes in baseline responding reported in Experiment I were not confined to cases in which the first and second signals in the signal-shock-signal arrangement were physically identical. It is suggested that the major effects of the conditioned-suppression procedure on response rate might not be confined to presentations of the signal.     

The neural basis of prolonged suppression of predatory attack. I. Naturally occurring physiological differences in the limbic systems of killer and non-killer cats

The epileptic excitability of the basolateral amygdala was found to correlate with differences in predatory and defensive predisposition of rat-killing cats and non-rat killers. The threshold for elicitation of afterdischarge (ADT) in the amygdalas of rat killers was higher than the ADTs of non-rat killers. Furthermore, non-rat killers with the lowest ADTs had the weakest attack tendencies and were most sensitive to a variety of environmental threats in addition to those posed by prey. These differences in excitability were not found in control areas lateral to the amygdala or in the ventral hippocampus. The possibility that ADT is a behaviorally relevant measure of a long-term predatory suppression function of the amygdala is discussed.     

Cognitive and physiological markers of emotional awareness in chimpanzees (Pan troglodytes)

The ability to understand emotion in others is one of the most important factors involved in regulating social interactions in primates. Such emotional awareness functions to coordinate activity among group members, enable the formation of long-lasting individual relationships, and facilitate the pursuit of shared interests. Despite these important evolutionary implications, comparative studies of emotional processing in humans and great apes are practically nonexistent, constituting a major gap in our understanding of the extent to which emotional awareness has played an important role in shaping human behavior and societies. This paper presents the results of two experiments that examine chimpanzees' responses to emotional stimuli. First, changes in peripheral skin temperature were measured while subjects viewed three categories of emotionally negative video scenes; conspecifics being injected with needles (INJ), darts and needles alone (DART), and conspecific directing agonism towards the veterinarians (CHASE). Second, chimpanzees were required to use facial expressions to categorize emotional video scenes, i.e., favorite food and objects and veterinarian procedures, according to their positive and negative valence. With no prior training, subjects spontaneously matched the emotional videos to conspecific facial expressions according to their shared emotional meaning, indicating that chimpanzee facial expressions are processed emotionally, as are human expressions. Decreases in peripheral skin temperature, indicative of negative sympathetic arousal, were significantly lower when subjects viewed the INJ and DART videos, compared to the CHASE videos, indicating greater negative arousal when viewing conspecifics being injected with needles, and needles themselves, than when viewing conspecifics engaged in general agonism. Accepted after revision: 8 April 2001 ❚ Electronic Publication     

Psychometric qualities of the White Bear Suppression Inventory in a Dutch sample of children and adolescents

The White Bear Suppression Inventory [WBSI; Wegner and Zanakos (1994)] was developed to assess the tendency to suppress unwanted thoughts. Most psychometric studies of the WBSI have included healthy students and adults with obsessive-compulsive disorder. There has been increasing interest in thought suppression in children and adolescents, especially after a traumatic event, but little is known about the psychometric properties of the WBSI for children. The aim of this research was to examine the psychometric qualities of the WBSI in a Dutch sample of children and adolescents. Two studies were conducted. First, the WBSI’s factor structure, internal consistency and test-retest stability were examined in a sample of 203 primary school children (9-13 years). Second, the factor structure and content validity were assessed in 89 children and adolescents (8-18 years) who attended the emergency room after a road traffic accident. Results demonstrated that the WBSI items contribute to a single factor measuring the suppression of unwanted thoughts and that the reliability is satisfactory. Associations between the WBSI and PTSD-symptoms demonstrated sufficient content validity. The findings suggest that the WBSI can appropriately be used in child and adolescent samples.     

Emotion regulation and aggression

This review considers the impact of deliberate emotion regulation on aggression, by integrating findings from recent emotion regulation research with a contemporary model of aggressive behavior, the General Aggression Model. First, it considers how individuals who under-regulate anger and other emotions may be more likely to behave aggressively in an attempt to repair, terminate, or avoid uncomfortable emotional states. Second, it explores how over-regulation of emotion may lead to aggressive behavior by increasing negative affect, reducing inhibitions against aggression, compromising decision making processes, diminishing social networks, increasing physiological arousal and hindering the resolution of difficult situations. Finally, it reviews three skills thought to underlie deliberate emotion regulation: emotional awareness, emotional acceptance and proficiency in a variety of emotion regulation strategies. Treatment encompassing all of these skills may improve an individual's ability to regulate difficult emotion states more adaptively and thereby lessen aggressive behavior.