Motivational effects of smoked marijuana: behavioral contingencies and low-probability activities.

Six adult male research volunteers, in two groups of 3 subjects each, lived in a residential laboratory for 15 days. All contact with the experimenters was through a networked computer system, and subjects' behavior was monitored continuously and recorded. During the first part of each day, they were allowed to socialize. Two cigarettes containing active marijuana (2.7% delta 9-THC) or placebo were smoked during the private work period and the period of access to social activities. Three-day contingency conditions requiring subjects to engage in a low-probability work activity (instrumental activity) in order to earn time that could be spent engaging in a high-probability work activity (contingent activity) were programmed during periods of placebo and active-marijuana smoking. During placebo administration, the contingency requirement reliably increased the amount of time that subjects spent engaged in the low-probability instrumental activity and decreased the time spent engaged in the high-probability activity. During active-marijuana administration, however, the increases in instrumental activity were consistently larger than observed under placebo conditions. The decreases in contingent activity were similar to those seen under placebo conditions. Smoking active marijuana was thus observed to produce increments in instrumental activity under motivational conditions involving contingencies for "work activities."     

Cross-informant consistency in externalizing and internalizing problems in early adolescence

The concept of cross-informant consistency has long been a topic of interest for those involved in assessment of behavior problems in adolescence. The purpose of the present study was to replicate and expand the existing literature by including four informants (mother, father, teacher, and adolescent self-report) and examining correlations among them as well as differences between reporters on an absolute level of both internalizing and externalizing problems. Fifty-two young adolescents (ranging in age from 11 to 15 years) and their mothers, fathers, and social studies teachers participated in the study. The Conduct Disorder subscale, Socialized Aggression subscale, and Anxiety/Withdrawal subscale of the Revised Behavior Problem Checklist were used. Results indicated that teachers showed little agreement with other informants on conduct problems (teachers reporting fewer problems), while parents and adolescents showed significant agreement. Informants showed no agreement on the measure of covert problems (socialized aggression), and all reports showed agreement on internalizing problems (although teachers continued to report fewer problems). Implications for assessment of young adolescents are discussed.This research was supported, in part, by the William T. Grant Foundation and the University of Georgia's Institute for Behavior Research.     

Context and companion's behavior as determinants of cooperation and competition in school-age children

Information about the social context and a companion's actions were studied as determinants of cooperation and competition in middle childhood. In Experiment 1, first-, third-, and fifth-grade children were told that they would play a board game with another same-age, same-sex child (actually a bogus companion). The experimenter's instructions established shared rewards or winner-take-all as outcome conditions. Preprogrammed responses—100% cooperative or 100% competitive—provided information about the companion's actions. Results revealed that the companion's responses alone determined cooperation and competition among the first graders. Third graders used both types of information. Fifth graders, however, demonstrated a bias to respond cooperatively whenever a cooperative cue was present. In Experiment 2, first-grade subjects were given extra rehearsal of the game strategies, a scorekeeping procedure for use during the game, or a combination of the two. Results indicated that, under these conditions, younger subjects were able to use the instructions about reward distribution as well as the companion's actions in guiding their social behavior.     

Signal frequency and shock probability as determinants of prolonged vigilance performance in rhesus monkeys

The effects of changing signal frequency on a prolonged vigilance task were investigated by systematically increasing the average inter-trial interval between successive signals. During a 6-hr watch, vigilance performance remained constant when the rate of signal presentation was 40, 20, and 10 per hour. When the rate of signal presentation was reduced to 7 or 4 per hour, marked decrements in detection performance were observed. Similar vigilance decrements occurred when the average rate of signals per hour was kept constant (10 per hour) and the probability of receiving a shock for missing a signal was systematically varied. The results of this study indicate the importance of reinforcement factors in the control and maintenance of vigilance performance.     

A content semantics for quantified relevant logics. I

We present an algebraic-style of semantics, which we call a content semantics, for quantified relevant logics based on the weak system BBQ. We show soundness and completeness for all quantificational logics extending BBQ and also treat reduced modelling for all systems containing BB ^d Q. The key idea of content semantics is that true entailments AB are represented under interpretation I as content containments, i.e. I(A)I(B) (or, the content of A contains that of B). This is opposed to the truth-functional way which represents true entailments as truth-preservations over all set-ups (or worlds), i.e. (VaK) (if I(A, a) = T then I(B, a)= T).This paper was presented to the Australasian Association for Logic Conference, held at the University of Auckland from 9–12th July, 1986. I wish to thank those present for some helpful comments. I also wish to thank Kit Fine for some useful discussion on some topics of this paper.     

Psychological Responses to the Threat of Nuclear War

We investigated the nature of psychological responses to the threat of nuclear war and the relationships between attitudes and behavior in three studies. The first was a quasi-experimental study of the effects of a film depiction of nuclear war on attitudes and behavior. Results suggested that exposure was mediated by a sense of control over political events, but that exposure itself had no significant effect on psychological responses to nuclear war. The second was an experimental investigation of the effects of efficacy enhancing, fear arousing, or informational tactics as well as individual differences on memory for relevant information and political activism on the issue of nuclear arms control. Results indicated that men exposed to the fear arousal tactic were less likely to take action than those exposed to information alone or efficacy enhancement, whereas women exposed to fear arousal were more likely to act. Gender differences are explained in terms of the socialization of male responses to fear, the "macho" response. Those who showed less denial were more likely to act, as were those who stated intentions to take action. The third study employed structural modeling to examine the relationships between attitudes and behavior. Results supported the Model of Reasoned Action (Fishbein & Ajzen, 1975) in showing that intentions to act mediated the relationship between attitudes and behavior on this issue.     

A comparison of 13-year-old boys with attention deficit and/or reading disorder on neuropsychological measures

This study compared 13 year-old-boys with attention deficit disorder (ADD) and/or reading disability (RD), and controls with neither disorder on a battery of verbal and nonverbal neuropsychological measures. The aim was to examine whether ADD was associated with a qualitatively distinct pattern of deficits compared with RD. None of the measures differentiated the boys with ADD-only from the controls; the only deficit associated with ADD was slightly lower IQ. RD, on the other hand, was associated with deficits in memory and verbal skills.The Dunedin Multidisciplinary Health and Development Research Unit is supported by the Medical Research Council of New Zealand and involves several Departments of the University of Otago. Much of the data are gathered by voluntary workers from the Dunedin community.The authors are indebted to the many people who contributions make this ongoing study possible. We wish to acknowledge the advice and help of Dr. P. A. Silva, director of the Dunedin Unit, in preparing this report.     

The structure and correlates of self-reported symptoms in 11-year-old children

Self-reports of DSM-III symptomatology were obtained from 792 11-year-old children using the Diagnostic Interview Schedule for Children (DISC). We report results concerning 13 subscales derived from the DISC. Factor-analysis of the subscales suggested a broad distinction between externalizing and internalizing disorder for boys' self-report. For girls, two separate internalizing factors representing anxiety and depression emerged. We also found sex differences in correlates of self-reported disorder. Finally, we examined agreement between child and parent and teacher reports. Overall, agreement was relatively low, although somewhat higher for child-parent than for child-teacher.The Dunedin Multidisciplinary Health and Development Research Unit is supported by the Medical Research Council of New Zealand and the Departments of Education and Health, and involves several departments of the University of Otago. Much of the data are gathered by voluntary workers from the Dunedin community. The authors are indebted to the many people whose contributions make this ongoing study possible.     

A content semantics for quantified relevant logics. II

In part I, we presented an algebraic-style of semantics, which we called “content semantics,” for quantified relevant logics based on the weak systemBBQ. We showed soundness and completeness with respect to theunreduced semantics ofBBQ. In part II, we proceed to show soundness and completeness for extensions ofBBQ with respect to this type of semantics. We introducereduced semantics which requires additional postulates for primeness and saturation. We then conclude by showing soundness and completeness forBB ^d Q and its extentions with respect to this reduced semantics.