The marked item technique: a practical procedure for litter control

Unobtrusively marked items of litter were placed among existing trash on the grounds of a federal youth correctional facility. Inmates voluntarily collected trash and deposited it at a central location, where they were given money or special privileges for each piece of marked litter found. A multiple-baseline design with litter counts in three areas revealed successive reductions of 55%, 88%, and 71% after 17, 22, and 36 days of baseline, respectively. A fourth area served as a baseline-only control, and revealed no systematic changes. Advantages of the procedure over previously devised techniques were discussed and applications in other areas of pollution control suggested.     

Chimpanzee gaze following in an object-choice task

Many primate species reliably track and follow the visual gaze of conspecifics and humans, even to locations above and behind the subject. However, it is not clear whether primates follow a human’s gaze to find hidden food under one of two containers in an object-choice task. In a series of experiments six adult female chimpanzees followed a human’s gaze (head and eye direction) to a distal location in space above and behind them, and checked back to the human’s face when they did not find anything interesting or unusual. This study also assessed whether these same subjects would also use the human’s gaze in an object-choice task with three types of occluders: barriers, tubes, and bowls. Barriers and tubes permitted the experimenter to see their contents (i.e., food) whereas bowls did not. Chimpanzees used the human’s gaze direction to choose the tube or barrier containing food but they did not use the human’s gaze to decide between bowls. Our findings allowed us to discard both simple orientation and understanding seeing-knowing in others as the explanations for gaze following in chimpanzees. However, they did not allow us to conclusively choose between orientation combined with foraging tendencies and understanding seeing in others. One interesting possibility raised by these results is that studies in which the human cannot see the reward at the time of subject choice may potentially be underestimating chimpanzees’ social knowledge. Received: 16 February 1998 / Accepted after revision: 5 July 1998     

A transfer of self-discrimination response functions through equivalence relations

The present study tested the idea that human self-discrimination response functions may transfer through equivalence relations. Four subjects were trained in six symbolic matching-to-sample tasks (if see A1, choose B1; A1-C1, A2-B2, A2-C2, A3-B3, A3-C3) and were then tested for the formation of three equivalence relations (B1-C1, B2-C2, B3-C3). Two of the B stimuli (B1 and B2) were then used to train two different self-discrimination responses using either detailed instructions (Subjects 1 to 3) or minimal instructions (Subject 4) on two complex schedules of reinforcement (i.e., subjects were trained to pick the B1 stimulus if they had not emitted a response, and to pick the B2 stimulus if they had emitted one or more responses on the previous schedule). All 4 subjects showed the predicted transfer of self-discrimination response functions through equivalence relations (i.e., no response on the schedule, pick C1; one or more responses on the schedule, pick C2). Subjects also demonstrated this transfer when they were required to discriminate their schedule performance before exposure to the schedule (i.e., “what I intend to do”). Four control subjects were also used in the study. Two of these (Subjects 5 and 6) were not exposed to any form of matching-to-sample training and testing (nonequivalence controls). The 2 remaining subjects (7 and 8) were exposed to matching-to-sample training and testing that incorporated stimuli not used during the transfer test; C1 and C2 were replaced by N1 and N2 during the matching-to-sample training and testing, but C1 and C2 were used for the transfer tests (equivalence controls). All 4 subjects failed to produce the self-discrimination transfer performances observed with the experimental subjects.     

A systematic review of definitions of motor vehicle headways in driver behaviour and performance studies

Headway is a safety measure commonly used to investigate driving behaviour and driver performance. Its purpose is to reflect the following distance or time between a leading and following vehicle in traffic. It is therefore associated with drivers’ response time, such as in braking or swerving, during safety critical events. In the literature, distance and time headway are defined in different ways, despite standard definitions in the traffic engineering literature, which prompted this systematic review of headway definitions across a range of study designs, in order to recommend approaches to improve the accuracy and reproducibility of headway definitions used in road safety contexts. PRISMA guidelines were followed to search four databases (EMBASE, COMPENDEX, SCOPUS and MEDLINE) for studies that reported on headways or discussed methodological approaches. The search and filtering of abstracts identified 110 articles for a qualitative synthesis. Four broad approaches to measuring headways were detected: studies using simulation, roadside external features, on-road features, and on-vehicle features. Studies were coded as to whether they included written explanation, mathematical statements, or pictorial depictions of headway. Only 49.6% of studies contextualised headway sufficiently for reproducibility. Reproducibility is crucial for accurate interpretation of research findings and comparisons across studies. It is recommended that headway definitions should a) exclude vehicle or parts of vehicle lengths, b) include reference points (e.g., bumper/axle/rear), c) have a consistent terminology, and d) include the accuracy of headway measuring devices to report the precision of a study’s findings.     

Automatic effects of instructions do not require the intention to execute these instructions

Prior research established that newly instructed stimulus-response mappings, which have never been executed overtly before, can lead to automatic response-congruency effects. Such instruction-based congruency effects have been taken as evidence for the hypothesis that the intention to execute stimulus-response mappings results into functional associations that serve future execution. The present study challenges this hypothesis by demonstrating in a series of four experiments that maintaining instructed stimulus-response mappings for future recognition, rather than for future execution, can also lead to an instruction-based congruency effect. These findings indicate that the instruction-based congruency effect emerges even when it is very unlikely that participants form the intention to execute instructions. Alternative interpretations of the instruction-based congruency effect are discussed.     

“要有创造性”指导语效应及其对创造性教学的启示

“要有创造性”指导语效应（effects of explicit instructions to“be creative”）,是指在创造力测验或实验任务中,明确要求“要有创造性”（be creative）的指导语,能够促进被试的创造性表现的现象。该效应的理论解释主要有最大化表现理论、目标设置理论和注意控制理论。在指导语中对“创造性”作出解释、创造性任务的类型以及被试特征,都会影响“要有创造性”指导语效应的产生。在创造性教学过程中,可以根据“要有创造性”指导语效应发生的机制,从设置创造性目标、根据任务特征施加精细指导、结合学生特征实施个性化教学三个方面,设计创造性活动,以促进学生创新能力的发展。     

What leads to coordinated attention in parent–toddler interactions? Children's hearing status matters

Coordinated attention between children and their parents plays an important role in their social, language, and cognitive development. The current study used head‐mounted eye‐trackers to investigate the effects of children's prelingual hearing loss on how they achieve coordinated attention with their hearing parents during free‐flowing object play. We found that toddlers with hearing loss (age: 24–37 months) had similar overall gaze patterns (e.g., gaze length and proportion of face looking) as their normal‐hearing peers. In addition, children's hearing status did not affect how likely parents and children attended to the same object at the same time during play. However, when following parents' attention, children with hearing loss used both parents' gaze directions and hand actions as cues, whereas children with normal hearing mainly relied on parents' hand actions. The diversity of pathways leading to coordinated attention suggests the flexibility and robustness of developing systems in using multiple pathways to achieve the same functional end.     

The effect of biased lineup instructions on eyewitness identification confidence

Although it is well‐known that biased lineup instructions (i.e., those that do not inform witnesses the perpetrator may not be in the lineup) inflate false identifications, their effects on witness confidence are less well understood due to methodological limitations of past studies. We report two studies that use novel methodologies to obviate these limitations. Study 1 (N = 177) demonstrated that biased lineup instructions increased witnesses' average estimates of the likelihood that a lineup member is guilty. Study 2 (N = 137) introduces a novel debiasing paradigm that allows a parsing of choosers into those who made an identification only because of the biased instructions (induced choosers), and those who would have chosen despite the instructions (inherent choosers). Biased lineup instructions inflated confidence only among induced choosers, but not among inherent choosers. Contrary to legal reasoning, witness confidence is an insufficient metric to determine the suggestiveness of biased instructions.