Koffka's effect is mediated by figure thickness at the joining region

Three-quarters of a century ago Gestalt psychologist Kurt Koffka described a remarkable effect: when a contiguous gray ring is placed on a background half one shade of gray, half another, the ring appears homogeneous. However, if the ring is divided, the two halves of the ring appear different shades of gray, the half of the ring on the darker background appearing lighter than the half of the ring on the lighter background. The Gestalt principle of continuity is used to explain this effect. But what microscopic principles might be mediating this effect? Recently we found sufficiently thin rings (annuli) appear heterogeneous even when geometrically continuous. Here, using crescent-shaped figures instead of the circular annuli used for the traditional Koffka effect, we show that this effect of thickness of the ring is mediated by the thickness at the boundary of the region where the halves of the figure are joined.     

Friend or foe? The role of latent inhibition in predator and non-predator labelling by coral reef fishes

In communities of high biodiversity, the ability to distinguish predators from non-predators is crucial for prey success. Learning often plays a vital role in the ability to distinguish species that are threatening from those that are not. Many prey animals learn to recognise predators based on a single conditioning event whereby they are exposed to the unknown predator at the same time as alarm cues released from injured conspecifics. The remarkable efficiency of such learning means that recognition mistakes may occur if prey inadvertently learn that a species is a predator when it is not. Latent inhibition is a means by which prey that are pre-exposed to an unknown species in the absence of negative reinforcement can learn that the unknown animal is likely not a threat. Learning through latent inhibition should be conservative because mistakenly identifying predators as non-predators can have fatal consequences. In this study, we demonstrated that a common coral reef fish, lemon damselfish, Pomacentrus moluccensis can learn to recognise a predator as non-threatening through latent inhibition. Furthermore, we showed that we could override the latent inhibition effect by conditioning the prey to recognise the predator numerous times. Our results highlight the ability of prey fish to continually update the information regarding the threat posed by other fishes in their vicinity.     

Intact and impaired mechanisms of action understanding in autism

Typically developing children understand and predict others' behavior by extracting and processing relevant information such as the logic of their actions within the situational constraints and the intentions conveyed by their gaze direction and emotional expressions. Children with autism have difficulties understanding and predicting others' actions. With the use of eye tracking and behavioral measures, we investigated action understanding mechanisms used by 18 children with autism and a well-matched group of 18 typically developing children. Results showed that children with autism (a) consider situational constraints in order to understand the logic of an agent's action and (b) show typical usage of the agent's emotional expressions to infer his or her intentions. We found (c) subtle atypicalities in the way children with autism respond to an agent's direct gaze and (d) marked impairments in their ability to attend to and interpret referential cues such as a head turn for understanding an agent's intentions.     

Facial Structure Is a Reliable Cue of Aggressive Behavior

ABSTRACT— Facial width-to-height ratio is a sexually dimorphic metric that is independent of body size and may have been shaped by sexual selection. We recently showed that this metric is correlated with behavioral aggression in men. In Study 1, observers estimated the propensity for aggression of men photographed displaying neutral facial expressions and for whom a behavioral measure of aggression was obtained. The estimates were correlated strongly with the facial width-to-height ratio of the stimulus faces and with the actual aggression of the men. These results were replicated in Study 2, in which the exposure to each stimulus face was shortened to 39 ms. Participants' estimates of aggression for each stimulus face were highly correlated between Study 2 (39-ms exposure) and Study 1 (2,000-ms exposure). These findings suggest that the facial width-to-height ratio may be a cue used to predict propensity for aggression in others.     

Social desirability in the bedroom: Role of approval motivation in sexual relationships

One-hundred and twelve unmarried participants completed a questionnaire that examined the relationship between gender and approval motivation (assessed by the Marlowe—Crowne Social Desirability Scale) and college students' stereotypes of and experiences with power in sexual encounters. Regardless of approval motivation, students described men as using power predominantly to have sex and women as using power predominantly to avoid having sex. However, interactions between need for approval and gender suggested that high-need-approval women might be having more experiences with sex and power in the bedroom than high-need-approval men. These results are discussed in light of Elkind's hypothesis that adolescent behavior conforms to an imaginary audience of peers and the Crowne-Marlowe model of approval motivation.An earlier version of this article was presented in the symposium Gender and Power Strategies: Contrasting Models and Applications, at the meeting of the American Psychological Association, Los Angeles, August 24–28, 1981. The authors wish to express appreciation to J. W. McCormick for his assistance with data analysis and to E. Allgeier for her helpful comments on a previous draft.     

Adolescents' values, sexuality, and contraception in a rural New York county

75 male and 88 female high school students in a rural county of New York completed a questionnaire asking about personal values and sexual experiences. Religiosity was not likely to affect the incidence of intercourse or effectiveness of contraceptive use. Students with more liberal premarital sexual and profeminist standards usually became more sexually intimate with their dates than did conservative students, but these standards did not predict coital frequency or effective contraceptive use. Different groups exhibited remarkably homogeneous sexual and contraceptive behavior. Nonvirgins had coitus sporadically or on the average of only twice a month. In addition, regardless of their values, most nonvirgins were contraceptive risk takers, partly for fear of interfering with pleasure, and partly because sporadic sex was not perceived by the adolescents to be risky. Rejecting the most, reliable methods available (e.g. birth control pills and IUDs), the condom was the most effective contraceptive used by the majority (57%) and 21% of the nonvirgins relied exclusively on such ineffective contraceptives as withdrawal, trusting in luck, and douching. Younger adolescents may be at particular risk, being more impulse motivated and egocentric, and less likely to seek adult-furnished family planning, especially in a rural community where anonymity is more difficult to protect. Given the uniformity of contraceptive behavior among younger adolescents, and the increasing likelihood of contraceptive use with increasing age of 1st coitus, future study will be needed on the impact of cognitive and emotional maturity, as well as that of environment and family planning resources on young adolescents' contraceptive use.