Adults' representations of division facts: a consequence of learning history?

There has been a recent increase in the study of adults' performance on simple division problems. Researchers up to now have focused on the relationship between multiplication and division and have found that multiplication often has a mediating role in the solution of division problems (Campbell, 1997, 1999; LeFevre & Morris, 1999; Mauro, LeFevre, & Morris, 2002). In this study, division was exclusively examined to determine the strategies that are used to solve these problems and to identify factors relating to particular strategy use. Thirty-two participants were asked to solve two sets of 64 simple division problems (from 4 divided by 2 to 81 divided by 9) and error, latency, and strategy report data were collected. Fewer errors were made on easy problems, which were also solved more quickly than difficult problems. Participants used retrieval, multiplication, and other strategies to solve the problems and tended to use retrieval more on easy than difficult problems and used multiplication more on difficult problems than easy problems. Unexpected age differences in strategy use were also found. Older participants tended to rely more heavily on retrieval than younger participants. These results suggest that older participants may have stronger representations for simple division problems than younger participants.     

School peer counselling for bullying services as a source of social support: a study with secondary school pupils

Individual interviews to solicit secondary school pupils' (N=99) views of the peer counselling for bullying service in their own school, with a focus on the issue of social support for bullying-related problems, were conducted. Three themes were addressed: (1) willingness to use the service relative to other potential sources of support, (2) preferred gender and age of peer counsellor, and (3) disclosure of using the service to friends. Most participants reported a willingness to use the service, but only around one in 20 would 'definitely not' do so. Relative to their willingness to use the service, participants were more willing to solicit help from friends, but less willing to solicit help from their form teacher and siblings. Around a third of participants expressed a preference for seeing a counsellor of a particular gender, and around two thirds expressed a preference for seeing one of a specific relative age. Several significant differences were obtained between girls and boys, and between users and non-users of the service. The results are discussed in terms of the implications for providers of peer counselling for bullying services.     

Choosing or Being Chosen by Aggressive–Disruptive Peers: Do They Contribute to Children's Externalizing and Internalizing Problems?

The goal of this study was to investigate the extent to which aggressive-disruptive peers contribute to the development of externalizing and internalizing problems in children, while controlling for children's own behavior. We examined 2 sets of peers: (1) those that the child nominated as friends, and (2) those that nominated the child as a friend. The participants were 236 boys and girls attending 3rd to 5th grade at the beginning of the study, who were followed over a period of 2 years. Results showed that choosing more aggressive peers on the nomination procedure was associated with more externalizing problems and self-reported depressive symptomatology over time. On the other hand, being liked by more aggressive children generally was not associated with elevated externalizing or internalizing problems.     

心理性应激的时间加工进程:来自ERP的证据*

采用有时间压力的算术题目诱发被试的心理性应激体验,并用事件相关电位技术(ERP)探讨心理性应激发生时大脑神经活动的时程变化。行为数据结果发现有时间压力下被试的反应时更短;脑电数据结果发现有时间压力组的容易题目比无时间压力组的容易题目诱发出更大的N1峰值、更长的P2潜伏期和更大的P300波幅;有时间压力组的困难题目比无时间压力组的困难题目同样诱发出更大的N1峰值、更长的P2潜伏期和更大的P300波幅,但这种组别主效应仅表现在部分电极点上。该研究结果表明心理性应激增加了早期知觉加工的负载,导致知觉加工速度减慢,在信息加工后期阶段需要占用更多的认知资源。     

Using the Internet to find offline sex partners.

We aimed to expand upon the demographic characteristics and gender differences among those who have met someone on the Internet who they later met offline and had sex with as well as any relationship with cybersex, sexually transmitted infections, and online sexual problems. We analyzed data collected through an online questionnaire in 2002 in Sweden including a total population of 1836 respondents of which 1458 used the Internet for sexual purposes. Of those, 35% men and 40% women reported to have met offline sex partners online. The majority reported an occurrence of one to two times, whereas 10% reported six or more times. The analysis suggested women aged 34-49 and 50-65 years, homo- and bisexual men, and singles more likely to have this experience. They were also more likely to have engaged in cybersex. No relationships were found with sexually transmitted infections or online sexual problems. The results suggest that using the Internet to find sex partners may be less hazardous for the general Internet users than pointed out by prior research about this behavior often focusing on specific sub groups of Internet users.     

Preference for gamma-hydroxybutyrate (GHB) in current users

Gamma-hydroxybutyrate (GHB) is a drug with significant abuse potential. The present study aimed to assess the relative value of escalating doses of GHB to current GHB users via the Multiple Choice Procedure (MCP), and to validate that the dose rated highest with the MCP would be self-administered at a greater rate than placebo. Participants were 5 current GHB users who were not currently trying to stop using GHB. To examine the value of escalating doses of GHB, the following doses of GHB were used: 0 (placebo), 12.5, 25, 37.5, and 50 mg/kg. Participants typically assigned higher doses of GHB had higher crossover points on the MCP. During choice sessions, participants made repeated choices between administering GHB, placebo or nothing. All participants selected GHB exclusively (5 out of 5 instances) except for one participant who selected GHB on 4 out of 5 instances, thus 96% (i.e., 24/25) of choices were for active GHB. Based on these data, GHB appears likely to function as a dose-dependent reinforcer for humans based on our sample.     

The role of task rules and stimulus–response mappings in the task switching paradigm

Switch costs occur whenever participants are asked to switch between two or more task sets. In a typical task switching experiment, participants have to switch between two task sets composed of up to four different stimuli per task set. These 2 (task sets) x 4 (stimuli) contain only 8 different stimulus-response (S-R) mappings, and the question is why participants base their task performance on task sets instead of S-R mappings. The current experiments compared task performance based on task rules with performance based on single stimulus-response mappings. Participants were led to learn eight different S-R mappings with or without fore-knowledge about two underlying task sets. Without task set information no difference between shifts and repetitions occurred, whereas introducing task sets at the beginning led to significant switch costs. Most importantly, introducing task sets in the middle of the experiment also resulted in significant switch costs. Furthermore, introducing task rules at the beginning of the experiment lead to slower RTs when simple stimuli (Experiment 1) had to be processed. This detrimental effect disappeared with more complex stimuli (Experiment 2). Results will be discussed with respect to cognitive control.     

The role of the sound of tapping for nonvisual judgment of gap crossability

The author investigated the possibility that nonvisual locomotion with a cane depends on the sound of the cane tapping. Blindfolded participants were asked to judge whether a gap in front of them could be crossed by walking. An acoustic analysis suggested that sound could, in theory, distinguish the gaps. Blindfolded sighted participants in Experiments 1 and 2 judged crossability under conditions in which only the sound of tapping was available and in which the sound was minimized; the third and fourth experiments included experienced cane users. Both inexperienced observers and experienced cane users were unaffected by sound reduction and were less able to discriminate gaps when using sound only than when using reduced sound. A fifth experiment indicated that active-passive differences were not responsible for these effects. Results indicate that sound is not necessary or sufficient for judging nonvisible crossability with a probe.     

The Use of Mental Health Services Among Victims of Partner Violence on College Campuses

The present study investigated the relationship between past victimization of different types of intimate partner violence (IPV; physical, psychological, and sexual) and the likelihood of using mental health services. Results indicate 86% of participants reported experiencing some form of IPV, but only 16% of those victims used mental health services to address emotional problems. The participants reported embarrassment, expense, ineffectiveness, and social stigma as the most prominent barriers to seeking help from a mental health professional. The study also found that participants who experienced physical and psychological IPV, but not sexual IPV, reported using mental health services. Sexual IPV may elicit different barriers in help-seeking behaviors. Implications for college IPV prevention programs and mental health services are discussed.     

Overcoming fixed mindsets: The role of affect

When there is an established strategy to solve a problem, we often approach the problem with a mindset that makes us blind for more efficient solutions. We examined the role of affect in overcoming such blinding effects of mindsets. As positive affect is known to broaden and negative affect to narrow thought–action repertoires, we speculated that positive affect facilitates and negative affect impedes the overcoming of a current mindset. To induce a mindset, participants initially solved 60 similar problems which were only solvable using the same complex strategy. After a short break in which positive or negative affect was induced, participants continued to work on the problems. Critically, there now was an additional simple way to solve the problems. Participants experiencing positive affect were more likely to detect the simple solution than participants experiencing negative affect. These findings reveal that affect modulates how much we are constrained by current mindsets.     

Understanding and using principles of arithmetic: operations involving negative numbers

Previous work has investigated adults' knowledge of principles for arithmetic with positive numbers ( Dixon, Deets, & Bangert, 2001 ). The current study extends this past work to address adults' knowledge of principles of arithmetic with a negative number, and also investigates links between knowledge of principles and problem representation. Participants ( N = 44) completed two tasks. In the Evaluation task, participants rated how well sets of equations were solved. Some sets violated principles of arithmetic and others did not. Participants rated non-violation sets higher than violation sets for two different principles for subtraction with a negative number. In the Word Problem task, participants read word problems and set up equations that could be used to solve them. Participants who displayed greater knowledge of principles of arithmetic with a negative number were more likely to set up equations that involved negative numbers. Thus, participants' knowledge of arithmetic principles was related to their problem representations.     

The long-term outcome of a personal network-oriented HIV prevention intervention for injection drug users: The SAFE study

Social influence processes have been found to affect numerous drug and health-related behaviors. We postulated that by using a network-oriented intervention it may be possible to capitalize on social influence processes to reduce human immunodeficiency virus (HIV) risk behaviors. The present study used an experimental study design for delivering a psychoeducational acquired immunodeficiency syndrome (AIDS) preventive intervention to injection drug sharing networks. Participants were recruited from the ALIVE study, an epidemiological study in Baltimore. In the present paper we examine the self-reported behavioral outcomes of 117 injection drug users 18 months after the baseline interview. HIV seronegative experimental participants reported significantly less frequent needle sharing and less injecting of heroin and cocaine than controls. In multiple logistic regression models of HIV seronegative participants, there was a significant negative association between assignment to the experimental group and the HIV-related behaviors of needle sharing and sharing of cookers in the prior 6 months; controls were 2.8 times more likely than experimentals to report needle sharing and were 2.7 times more likely to report sharing cookers. The results of this 18-month follow-up suggest that among injection drug users network-oriented interventions may be a promising approach to HIV prevention.     

Beyond quantity: Individual differences in working memory and the ordinal understanding of numerical symbols

In two different contexts, we examined the hypothesis that individual differences in working memory (WM) capacity are related to the tendency to infer complex, ordinal relationships between numerical symbols. In Experiment 1, we assessed whether this tendency arises in a learning context that involves mapping novel symbols to quantities by training adult participants to associate dot-quantities with novel symbols, the overall relative order of which had to be inferred. Performance was best for participants who were higher in WM capacity (HWMs). HWMs also learned ordinal information about the symbols that lower WM individuals (LWMs) did not. In Experiment 2, we examined whether WM relates to performance when participants are explicitly instructed to make numerical order judgments about highly enculturated numerical symbols by having participants indicate whether sets of three Arabic numerals were in increasing order. All participants responded faster when sequential sets (3-4-5) were in order than when they were not. However, only HWMs responded faster when non-sequential, patterned sets (1-3-5) were in order, suggesting they were accessing ordinal associations that LWMs were not. Taken together, these experiments indicate that WM capacity plays a key role in extending symbolic number representations beyond their quantity referents to include symbol-symbol ordinal associations, both in a learning context and in terms of explicitly accessing ordinal relationships in highly enculturated stimuli.     

The Use of Environmental Clues During Incubation

ABSTRACT: Three experiments tested the prediction that incubation effects are caused by interactions between activation and environmental clues. Participants worked on 20 experimental problems and then were informed that they would have a second chance to work on the problems. Half were told they might see clues before returning to the problems and were instructed to try to use such clues. Participants then had an incubation period during which they generated words from the letters of test words. The test words were either semantically related to experimental problem answers, the actual answers, or unrelated words. Finally, all participants again tried to solve the experimental problems. Resolution, calculated as the number of items solved during the second trial that were not solved initially, was measured. Participants who saw answers during incubation resolved more items than those who saw related words. In Experiment 3, participants receiving no instructions did not differ across clue conditions, whereas instructed participants who saw answers resolved more problems than those who received related words. Participants in the instructed and unrelated condition performed significantly worse than those in the instructed and answer condition. Incubation effects occurred only when participants who were shown answers were also given instructions. No support was found for the theory that incubation effects are caused solely by environmental clues and activation.     

Evaluating pedestrian interaction preferences with a game theoretic autonomous vehicle in virtual reality

Localisation and navigation of autonomous vehicles (AVs) in static environments are now solved problems, but how to control their interactions with other road users in mixed traffic environments, especially with pedestrians, remains an open question. Recent work has begun to apply game theory to model and control AV-pedestrian interactions as they compete for space on the road whilst trying to avoid collisions. But this game theory model has been developed only in unrealistic lab environments. To improve their realism, this study empirically examines pedestrian behaviour during road crossing in the presence of approaching autonomous vehicles in more realistic virtual reality (VR) environments. The autonomous vehicles are controlled using game theory, and this study seeks to find the best parameters for these controls to produce comfortable interactions for the pedestrians. In a first experiment, participants’ trajectories reveal a more cautious crossing behaviour in VR than in previous laboratory experiments. In two further experiments, a gradient descent approach is used to investigate participants’ preference for AV driving style. The results show that the majority of participants were not expecting the AV to stop in some scenarios, and there was no change in their crossing behaviour in two environments and with different car models suggestive of car and last-mile style vehicles. These results provide some initial estimates for game theoretic parameters needed by future AVs in their pedestrian interactions and more generally show how such parameters can be inferred from virtual reality experiments.     

Simple lines and shapes are associated with,and communicate,distinct emotions

We investigated whether lines and shapes that present face-like features would be associated with emotions. In Experiment 1, participants associated concave, convex, or straight lines with the words happy or sad. Participants found it easiest to associate the concave line with happy and the convex line with sad. In Experiment 2, participants rated (valence, pleasantness, liking, and tension) and categorised (valence and emotion words) two convex and concave lines that were paired with six distinct pairs of eyes. The presence of eyes affected participants’ valence ratings and response latencies; more congruent eye–mouth matches produced more consistent ratings and faster reaction times. In Experiment 3, we examined whether dots that resembled eyes would be associated with emotional words. Participants found it easier to match certain sets of dots with specific emotions. These results suggest that facial gestures that are associated with specific emotions can be captured using relatively simple shapes and lines.     

Conditional reasoning,frequency of counterexamples,and the effect of response modality

Geiger and Oberauer (2007) found that when asked to reason with conditionals, people are very sensitive to information about the relative frequency of exceptions to conditional rules and quite insensitive to the relative number of disabling conditions. They asked participants to rate their degree of certainty in a conclusion. In the following studies, we investigated the possibility that this kind of response encourages a more probabilistic mode of processing compared with the usual dichotomous response. In Study 1, participants were given a variant of the problems used by Geiger and Oberauer with either the samescaled response format or a dichotomouscategorical response. The results with the scaled response were identical to those of Geiger and Oberauer. However, the results with the categorical response presented a very different profile. In Study 2, we presented similar problems using only frequency information, followed by a set of abstract conditional reasoning problems. The participants who performed better on the abstract problems showed a significantly different response profile than those who did worse on the abstract problems in the categorical response condition. No such difference was observed in the scaled response condition. These results show that response modality strongly affects the way in which information is processed in otherwise identical inferential problems and they are consistent with the idea that scaled responses promote a probabilistic mode of processing.     

Developmental differences in understanding of balance scales in the United States and Zimbabwe

This cross-cultural, developmental study of understanding of the physics of a balance scale involved 2 age groups (5- and 22-year-olds) in 2 countries (the United States and Zimbabwe). A factorial design was used. Each participant solved 6 types of balance scale problems, and the patterns of errors for these problem types were analyzed to determine which rules and concepts the participant used (e.g., whether number of weights was considered). As expected, on average, older participants were more accurate than younger participants, although significant age differences in the Zimbabwean sample were not found for problems solved by weight or distance cues. One finding differing from earlier research was that problems in which the beam balanced were more difficult for all participants. Generally, understanding of the physics of a balance scale appeared fairly similar in the 2 countries. Some cultural practices may account for the findings--in particular, the availability of preschool and age at time of academic specialization in higher education.     

HIV prevention among drug users: outcome of a network-oriented peer outreach intervention.

A network-oriented HIV prevention intervention based on social identity theory and peer outreach was implemented for HIV positive and negative drug users. A community sample of 250 were randomly assigned to an equal-attention control condition or a multisession, small-group experimental condition, which encouraged peer outreach; 94% of participants were African American, and 66% used cocaine or opiates. At follow-up, 92% of participants returned, and experimental compared with control group participants were 3 times more likely to report reduction of injection risk behaviors and 4 times more likely to report increased condom use with casual sex partners. Results suggest that psychosocial intervention emphasizing prosocial roles and social identity, and incorporating peer outreach strategies, can reduce HIV risk in low-income, drug-using communities.     

Depressed versus nondepressed young adult tobacco users: differences in coping style, weight concerns and exercise level.

Undergraduates age 18 to 24 years (n=656) completed questionnaires assessing tobacco use, depressive symptoms, coping responses, weight concerns, and exercise. The majority of participants were female (72%), White/non-Hispanic (95%), and in the 1st or 2nd year of college (80%). Current tobacco users (n=236) had a higher frequency of depression (40%) than never tobacco users (32%; p=.05). Tobacco users classified as depressed (Center for Epidemiological Studies Depression Scale [CES-D] score a 16) reported greater weight concerns and more frequent maladaptive coping in response to negative mood than tobacco users classified as nondepressed (CES-D score<16). Multivariate logistic regression analysis indicated that higher maladaptive coping and lower level of exercise were significantly associated with depression among tobacco users.