Additivity and expected utility in risky multiattribute preferences

This experiment analyzed human preferences among even chance gambles for commodity bundles. The purpose of the experiment was to test several independence assumptions that distinguish between models for risky multiattribute preferences. In particular, the additivity and the expected utility part of the additive expected utility model were tested symmetrically. The degree and form of model violations were established, and the effects of instructions and of response modes were examined. All independence assumptions were violated by a bias to prefer a gamble or a commodity bundle that was previously matched against a standard. Systematic and strong violations that superseded this bias questioned the validity of the additive expected utility model. In violation of the additivity part of that model subjects consistently preferred the gamble with more balanced outcomes when comparing gambles with identical marginal probability distributions. This trend, called multiattribute risk aversion, was independent of subjects' single attribute risk attitude. Instructions and response modes had no noticeable impacts on these response patterns.     

Self-image,perception of peers' risk acceptance and risky shift

Twelve four-person female groups of subjects displaying the typical underestimation of their peers' (relative to their own) risk acceptance were compared with twelve groups of subjects who (slightly) overestimated their peers' risk acceptance. Risk level was measured by responses to a set of hypothetical decision situations known to elicit risky shift on the basis of previous research. Risky shift following group discussion was not found to be different for the two types of groups, casting doubt on the widely suggested role of peer underestimation in risky shift. Nor was risky shift affected by whether or not group members stated their individual decisions publicly at the close of discussion. Larger group risky shifts were accompanied by higher self-ratings given by group members on a number of polarity scales. In discussing the findings, we outline an explanation of group-induced shifts in risk taking, emphasizing the motivational and informational inducements provided by group discussion whereby group members come to discard their prior positions in favor of more aspired ones.     

Responsibility diffusion and drive enhancement effects on risky shift1

Discussion produced expected risky and cautious shifts on choice dilemma items It was predicted from responsibility diffusion theory that, compared with low-anxious, high-defensive groups, high-anxious, low-defensive groups produce greater risky shift It was predicted from drive enhancement theory that, compared with low-anxious groups, high-anxious groups produce greater risky shift on risk-dominant items and greater cautious shift on caution-dominant items The results of two experiments failed to confirm either interpretation Surprisingly, significant shifts were obtained in a control condition     

Ontogenetic shift of spectral phototactic preferences in anuran tadpoles.

Tadpoles of three species of anurans initially had a midspectrum ("green") preference in laboratory phototactic tests, which was shown experimentally to involve a form of true color vision in one species and probably in the other two as well. During development, the preference shifted to shorter wave-lengths (higher frequencies) until a short-wavelength ("blue") preference predominated in the pre- and postmetamorphic stages and in the adults of six species tested; color vision was involved in all of these stages. The green preference of young tadpoles is ecologically adaptive, in that it directs larvae to green plants that provide food or shelter. Tadpoles observed in a pond congregated heavily in vegetated areas rather than in open water. Spectroradiometric field measurements showed that pond illumination in vegetated areas had a more highly saturated yellow-green spectral dominance compared with a desaturated white illumination in open water. During all ontogenetic stages and as adults, the animals had a preference for high illuminance of white light, which correlates with the high illumination of their habitat. Microspectrophotometric data from Liebman and Entine suggested that the green rods are active receptors in tadpoles, making unlikely Muntz's hypothesis that the ontogenetic shift in spectral preferences is due to premetamorphic maturation of these receptors. However, the visual pigments of all five types of photoreceptors shifted from vitamin A2- to vitamin A1-based chromophores during ontogeny, and the resulting shift in spectral response of the receptors might be related to the spectral shift in phototactic preferences.     

Psychophysiological assessment of change in erotic preferences

The difficulties involved in validating effectiveness of the various therapies of anomalous erotic preferences are often underestimated. Basically, methods of physiological assessment of erotic preferences would appear to be promising. However they still pose considerable problems. There are two kinds of such methods, those where measurement of general arousal is employed, and those which are based on assessment of sexual arousal proper. The former are only weak indicators of erotic preferences; the latter are to date represented only by assessment of penile volume changes to various kinds of potentially erotic stimuli (the phallometric test). The usefulness of the latter method in assessment of (therapeutic) changes in erotic preferences is basically limited to one particular situation only.Directions are pointed out in which this test is to be further developed to make it more generally useful as an indicator of (therapeutic) change in erotic preferences.     

Group status drives majority and minority integration preferences

This research examined preferences for national- and campus-level assimilative and pluralistic policies among Black and White students under different contexts, as majority- and minority-group members. We targeted attitudes at two universities, one where 85% of the student body is White, and another where 76% of students are Black. The results revealed that when a group constituted the majority, its members generally preferred assimilationist policies, and when a group constituted the minority, its members generally preferred pluralistic policies. The results support a functional perspective: Both majority and minority groups seek to protect and enhance their collective identities.     

Group shift to caution at the race track

Group and individual riskiness were compared on $2 “win” best at the race track. Using the standard pretest-posttest risk-shift design, group discussion to unanimous decision was found to produce a cautious shift in group bets.     

An automated apparatus for the assessment of social preferences in rodents

Preference apparatuses offer a straightforward method for the assessment of social preference in a controlled manner. The present paper provides the information necessary for the construction of an automated preference apparatus for rodents and a demonstration of the operation of this apparatus. In a representative study,Peromyscus polionotus females demonstrated preference for intact over castrated males.     

Ethical problems in research on risky behaviors and risky populations

The articles by Brooks-Gunn, Fisher, Hoagwood, Liss and Scott-Jones (all in this issue) present a panoply of real-world ethical issues in conducting scientific research on risky behaviors of children, adolescents, and their parents, particularly those from vulnerable populations. The universal, ethical principles of beneficence, justice, and respect for others are always applicable, but they do not resolve issues of child assent, parental consent, legal reporting requirements for illegal behaviors, and the special problems of studying risky behaviors in risky populations. Taken as a group, the articles raise some of the most interesting ethical problems that arise in developmental research. My discussion elaborates some issues and fails to resolve others. I hold the view that both science and ethics can be served by thoughtfully designed and implemented research on important social issues, but that the studies themselves cannot simultaneously solve the many societal problems of participants and be scientifically credible.     

The shift in infant preferences for vowel duration and pitch contour between 6 and 10 months of age

This study investigates the influence of the acoustic properties of vowels on 6‐ and 10‐month‐old infants’ speech preferences. The shape of the contour (bell or monotonic) and the duration (normal or stretched) of vowels were manipulated in words containing the vowels /i/ and /u/, and presented to infants using a two‐choice preference procedure. Experiment 1 examined contour shape: infants heard either normal‐duration bell‐shaped and monotonic contours, or the same two contours with stretched duration. The results show that 6‐month‐olds preferred bell to monotonic contours, whereas 10‐month‐olds preferred monotonic to bell contours. In Experiment 2, infants heard either normal‐duration and stretched bell contours, or normal‐duration and stretched monotonic contours. As in Experiment 1, infants showed age‐specific preferences, with 6‐month‐olds preferring stretched vowels, and 10‐month‐olds preferring normal‐duration vowels. Infants’ attention to the acoustic qualities of vowels, and to speech in general, undergoes a dramatic transformation in the final months of the first year, a transformation that aligns with the emergence of other developmental milestones in speech perception.     

Group climate in a stress discussion group for medical interns

In order to better characterize group process, the short form of the Group Climate Questionnaire (GCQS) was used to study a stress discussion group for medical interns. This group was found to be significantly different from a normative psychotherapy group sample along three major dimensions: Engaged, Avoiding and Conflict. The group members were cohesive, involved and open, yet respectful of each other's privacy. These results are discussed with respect to the group's goals and leadership.The authors thank George Fein, Ph.D., for statistical assistance.     

Group discussion and first advocacy effects in computer-mediated and face-to-face decision making groups

This study examines whether the first group member to advocate a position in the group publically has disproportionate influence on the group decision, and whether group discussion by computer mail or face-to-face determines the extent of the first advocate's influence. Possible explanations of first advocacy influence were tested in an experiment that allowed simultaneous observation of three independent variables: (1) assignment of first advocate (self-selected/randomly assigned), (2) early discussion before advocacy (discussion/no discussion), and (3) mode of communication (face-to-face/electronic mail). It was assumed that a first advocate effect exists if the group choice is closer to the first advocates' stated positions than to the group's average pregroup preferences. An “influence” hypothesis predicts that first advocates who self-select will be closer to the group decision than average pregroup preferences because these are first advocates most likely to persuade other members of the group. A “listening” hypothesis predicts that first advocates who hear an early group discussion will be closer to the group decision than average pregroup preferences because these first advocates are able to anticipate the group decision as a result of listening to what is communicated in group discussion. The results indicated strong support for the “listening” hypothesis. When groups held early discussions before someone advocated a position, the first advocate effect was observed; when groups did not hold early discussions but began their task by having someone advocate a position, there was no first advocate effect. The data suggest that the content and tone of electronic group discussions was qualitatively different from face-to-face group discussions, but the process of group decision making in both conditions was about the same. The implications of these results for group discussion and computer-mediated group decision making in organizations are discussed.     

Negative urgency and risky sexual behaviors: A clarification of the relationship between impulsivity and risky sexual behavior

How does impulsivity relate to risky sexual behavior? Whereas some research has attempted to answer this question in terms of global impulsivity, past research has demonstrated the need to conceptualize impulsivity as a multifaceted trait (Whiteside & Lynam, 2001). Research has been mixed as to which facets of impulsivity predict risky sexual behavior. The major aim of this project was to further the understanding between the five facets of impulsivity (positive urgency, negative urgency, lack of premeditation, sensation-seeking, and lack of perseverance) and risky sexual behavior. This study used a longitudinal design and showed that risky sex was highest among people who act rashly on the basis of negative emotion (negative urgency) and who crave novel, exciting situations (sensation seeking). These findings add to a growing body of literature on the importance of different facets of impulsivity in predicting risky sexual behavior.     

British men's hair color preferences: an assessment of courtship solicitation and stimulus ratings

Two studies examined the influence of women's hair color on approach behavior by British men and on ratings of physical attractiveness and personality. In Study 1, a female confederate whose hair color was dyed blonde, brunette, or red was instructed to sit in several nightclubs. It was found that she was approached significantly more frequently by men in the blonde condition. In Study 2, images of the same confederate were rated by 126 men. Results showed that the brunette stimulus was rated as more physically attractive, intelligent, approachable, competent, and arrogant, whereas the blonde stimulus was rated as more needy. These results are discussed in relation to the literature on hair color and attractiveness, but also in terms of women's own perceptions of their hair color.