Naltrexone-reversible pain suppression in the isolated attacking mouse

Fighting pairs of isolated DBA/2 mice showed a significant increase in tail-flick response latencies independent of whether opponents were losing or winning the combat. The effect lasted less than 10 min in both animals. Elevated pain thresholds were also found in isolates that attacked a nonaggressive conspecific, and were prevented by naltrexone (0.2 mg/kg), while a larger dose (1.0 mg/kg) inhibited the attack behavior. A small increase in pain threshold was observed after exposure of isolates to the test box alone, while isolation per se had no effect on baseline tail-flick latencies. The data demonstrate that endogenous pain suppressing systems are activated during attack and suggest that this opioid-mediated antinociception is a correlate of the isolation syndrome, reflecting enhanced arousal of the attacking animal.     

Interactions between area and numerosity

Summary The concept of filled area, i.e. the impressionistic ensemble of parts of a stimulus field occupied by dots, is used to account for various kinds of numerosity illusions due to perceptual interaction between a number of dots and their spatial arrangement. A measure of filled area is derived from a model for the perceptual clustering of dots on the basis of relative proximity. It is shown that the quantified concept of filled area successfully predicts illusion data from earlier studies. Subsequently, a two-alternatives forced-choice numerosity experiment is reported, the data of which gave further evidence of the predictive power of the filled-area hypothesis. Our approach is discussed with respect to spatial features of dot stimuli that might be in rivalry with the filled-area factor in numerosity-estimation tasks.     

Cance and luck are not the same

In the mind of many people chance and luck act as real but different causes of events. Even in strictly defined situations as casino gambling, people may perceive influences of luck that help to overcome the negative expectancy defined by the rules of chance. Interviews with gamblers in casinos confirmed this idea. In two experiments it was established that the distinction between chance and luck are also made by ordinary subjects in everyday situations. The results revealed that chance is perceived to operate when an event is surprising, an unexpected coincidence. Luck is perceived when an event implies the escape from negative consequences, or the achievement of something that is important and difficult. The distinction between chance and luck can explain why people are trapped by the illusion of control, even when it is clear that they have no influence on the physical causation determining the outcomes of events. They cannot change the outcome of the roulette wheel, but they can employ their luck, which helps them to place their bets on the winning number.     

The development and adoption of controversial default technologies

Default technologies evolve from failure. Within the realm of human behavior, technologies based on the use of aversive contingencies can be conceptualized as default technologies because they come into play when natural contingencies or positive reinforcement fail to produce a desired behavioral outcome. Historical as well as contemporary events suggest that it is a mistake for behavior analysts to advocate for the adoption of aversive technologies. We must, however, continue to play a leading role in the development of such technologies so that they will be used in an appropriate manner. Furthermore, the eventual elimination of aversive technologies will be possible only through continued, careful, and experimental analysis of the contexts of failure in which they are born.     

Maternal handling and motor development: an intracultural study

Citing a distinction between informal and formal routines used by mothers in handling their infants, we examined formal handling routines, in which the caregiver acts in a pedagogical manner; these routines are widespread in many non-Western countries. We hypothesised that formal handling serves to facilitate gross motor development during early infancy. To examine this hypothesis, the effects of a Jamaican formal handling routine on a broad range of developmental outcomes was examined. Results showed that the effects were specific to early gross motor development and in particular to postural control along the vertical axis of the body. Information is also provided on other aspects of Jamaican child care. It seems that the handling routine forms part of a folk (developmental) medicine system and may serve not only to promote child health but also as a sort of developmental neurological examination.