Selective sensitivity of schedule-induced activity to an operant suppression contingency.

The sensitivity of pigeons' schedule-induced activity to operant consequences was studied in two experiments. During a 30-s interval between food presentations, a keylight stimulus brightened incrementally. Stable terminal key pecking and interim locomotor activity developed. An operant "setback" contingency was applied to activity. The contingency arranged for locomotor movements (detected by a nine-panel floorboard) to be followed by a resetting of the keylight brightness to a dimmer value and a 1-s delay of reinforcement (for individual responses). Experiment 1 showed that activity patterns were highly sensitive to their operant consequences. Accompanying key-peck rates were only transiently affected. In Experiment 2, the setback contingency was imposed during restricted portions of the trial, and differential operant control of activity was demonstrated. However, birds in this study produced higher rates of key pecking as activity rates were reduced. These results suggest that although schedule-induced activity arises in response to the temporal arrangement of stimulus events, this behavior may retain considerable sensitivity to response-consequence relations.     

Infant cry as a graded signal: Experimental modifications of durations of pauses and expiratory sounds alter mothers' perceptions

The purpose of this study was to examine experimentally the effects of the temporal structure of infant crying on mothers' perceptions. Eighteen mothers of young infants rated variations of a 10-sec cry in which durations of all expiratory sounds and pauses were digitally lengthened and shortened by 50%. Results showed a general monotonic effect in which cries with increasingly shorter pauses were perceived to be more arousing, aversive, informative, and rough. Similarly, cries with short expirations were perceived to be more rhythmic and rough than cries with long expirations. The strength of the monotonic effect for pause duration on ratings of urgency interacted with the duration of expiratory sounds such that the combination of short pauses and short expirations created the greatest perceived urgency. This study replicates and extends previous findings which show that gradations in acoustic features of crying are associated with gradations in the intensity of adults' perceptions.     

"Turning back the clock" on serial-stimulus sign tracking.

Two experiments examined the effects of a negative (setback) response contingency on key pecking engendered by a changing light-intensity stimulus clock (ramp stimulus) signaling fixed-time 30-s food deliveries. The response contingency specified that responses would immediately decrease the light-intensity value, and, because food was delivered only after the highest intensity value was presented, would delay food delivery by 1 s for each response. The first experiment examined the acquisition and maintenance of responding for a group trained with the contingency in effect and for a group trained on a response-independent schedule with the ramp stimulus prior to introduction of the contingency. The first group acquired low rates of key pecking, and, after considerable exposure to the contingency, those rates were reduced to low levels. The rates of responding for the second group were reduced very rapidly (within four to five trials) after introduction of the setback contingency. For both groups, rates of responding increased for all but 1 bird when the contingency was removed. A second experiment compared the separate effects of each part of the response contingency. One group was exposed only to the stimulus setback (stimulus only), and a second group was exposed only to the delay of the reinforcer (delay only). The stimulus-only group's rates of responding were immediately reduced to moderate levels, but for most of the birds, these rates recovered quickly when the contingency was removed. The delay-only groups's rates decreased after several trials, to very low levels, and recovery of responding took several sessions once the contingency was removed. The results suggest that (a) sign-tracking behavior elicited by an added clock stimulus may be reduced rapidly and persistently when a setback contingency is imposed, and (b) the success of the contingency is due both to response-dependent stimulus change and response-dependent alterations in the frequency of food delivery. The operation of the contingency is compared with the effects of secondary reinforcement and punishment procedures.     

The control of responding by auditory stimuli: interactions between different dimensions of the stimuli.

Sounds have position in addition to other dimensions, such as intensity and frequency. Position rapidly gains control of spatially contiguous responses and this may interfere with control of responding by other acoustic dimensions. These experiments investigated interference of a tone-noise discrimination by the discrimination of acoustic position. Squirrel monkeys were studied when responding was differentially reinforced in the presence of both spectral content (tone-noise) and positional differences between the stimuli, and when responding was differentially reinforced only in the presence of spectral differences. Under the first condition, responding rapidly came under the control of the position of the noise in the two monkeys tested. The position of the tone controlled responding in one monkey; in the second monkey, responding came under the control of the spectral content of the tone. Under the second condition, responding was initially under the control of the noise in all three monkeys tested. This persisted for the duration of the condition for two of the monkeys; in one monkey, responding came under the control of the spectral content of the noise. Under the second condition, responding was also initially under the control of the position of the tone for all monkeys, but control by spectral content of the tone relatively rapidly developed in two of three monkeys.     

Safety of bicyclists in roundabouts with mixed traffic: Video analyses of behavioural and surrogate safety indicators

Although converting an intersection into a roundabout has been shown to result in fewer injury accidents for both motor vehicle drivers and pedestrians, the effect on bicyclists’ safety is unclear or even negative. This study focuses on roundabouts without bicycle facilities (i.e., mixed traffic conditions) and makes use of semi-automated video observation software with the aim of analysing bicyclists’ behaviour and safety on roundabouts with different diameter. Four urban roundabouts in Belgium are observed. Interactions between bicyclists and other vehicles are analysed using speed, lateral position and five indicators to describe the closeness of interactions (TTC_min, PET, T_{2 min}, lateral overtaking proximity and minimum distance headway). Additionally, the lateral position and riding speed of bicyclists that are in interaction with other vehicles is compared with the behaviour of bicyclists that are not in interaction with other vehicles.The behavioural analysis revealed that regardless of the type of condition (free-flow bicyclists or different interactions bicyclist-car), bicyclists always ride faster on roundabouts with big diameter and slower on roundabouts with small diameter. Moreover, bicyclists ride closer to the central island on roundabouts with big diameter compared to roundabouts with small diameter for all the conditions analysed.The analysis of surrogate safety indicators (TTC_min, PET, T_{2 min}) revealed that close interactions between bicyclists and cars are relatively frequent at both small and big roundabouts. The percentages of close interactions are more or less equal for roundabouts with big diameter (7.86% of observed interactions) and roundabouts with small diameter (8.24%). The analysis of the indicators to describe the closeness of interactions also showed that the closest interactions at roundabouts are all situations where the bicyclist has a leading role. The analysis of the most common types of close interactions revealed indeed that the most common close interactions are interactions where the bicyclist is entering the roundabout. The analysis of lateral overtaking proximity showed that bicyclists who overtake a car take smaller lateral overtaking proximities compared to cars overtaking a bicyclist. The analysis of minimum distance headway finally revealed that bicyclists who ride behind a car take smaller distance headways compared to cars driving behind a bicyclist.     

Investigating social functioning after early mild TBI: the quality of parent–child interactions

The young brain is particularly vulnerable to injury due to inherent physiological and developmental factors, and even mild forms of traumatic brain injury (mTBI) can sometimes result in cognitive and behavioural difficulties. Despite the high prevalence of paediatric mTBI, little is known of its impact on children's social functioning. Parent–child relationships represent the centre of young children's social environments and are therefore ideal contexts for studying the potential effects of mTBI on children's social functioning. The aim of this study was to assess the quality of parent–child interactions after mTBI using observational assessment methods and parental report. The sample included 130 children (18–60 months at recruitment) divided into three groups: children with uncomplicated mTBI (n = 47), children with orthopaedic injury (OI, n = 27), and non‐injured children (NI, n = 56). The quality of parent–child interactions was assessed 6 months post‐injury using the Mutually Responsive Orientation (MRO) scale, an observational measure which focuses on the dyadic nature of parent–child exchanges, and the Parental Stress Index questionnaire (Parent‐Child Dysfunctional Interaction (PCDI) domain). Significant differences with medium effect sizes were found between the mTBI group and the NI group on the MRO, but not between the OI group and the other two groups. PCDI scores did not differ across groups, suggesting that observational measures may be more sensitive to changes in parent–child interactions after TBI. The current findings have implications for children's post‐injury social development and highlight the importance of monitoring social outcomes even after minor head injuries.     

Young children's television viewing and the quality of their interactions with parents: A prospective community study

Television is one of the most commonly viewed forms of media by children throughout the world. Excessive television viewing can influence the quality of children's relationships and interactions with their parents. We examined the emotional availability (EA ) of children toward their parents by assessing child responsiveness and child involvement , using a cross‐sectional and longitudinal design. We employed a large and representative community sample of Norwegian 4‐year‐olds (n = 995) who were followed up at 6 years old (n = 795). The results illustrate that, when viewing excessive amounts of television, children are less likely to be involved with their parents in ordinary toy‐play. We argue in favor of the displacement hypothesis, stating that time‐demanding technologies are negatively related to the quality of parent–child relationships because spending more time watching television will leave less time for developing nurturing social relationships.     

Children's reasoning with peers in cooperative and competitive contexts

We report two studies that demonstrate how five‐ and seven‐year‐olds adapt their production of arguments to either a cooperative or a competitive context. Two games elicited agreements from peer dyads about placing animals on either of two halves of a playing field owned by either child. Children had to produce arguments to justify these decisions. Played in a competitive context that encouraged placing animals on one's own half, children's arguments showed a bias that was the result of withholding known arguments. In a cooperative context, children produced not only more arguments, but also more ‘two‐sided’ arguments. Also, seven‐year‐olds demonstrated a more frequent and strategic use of arguments that specifically refuted decisions that would favour their peers. The results suggest that cooperative contexts provide a more motivating context for children to produce arguments.

Statement of contribution

What is already known on this subject ?

• Reasoning is a social skill that allows people to reach joint decisions.
• Preschoolers give reasons for their proposals in their peer conversations.
• By adolescence, children use sophisticated arguments (e.g., refutations and rebuttals).

What the present study adds?

• Cooperation offers a more motivating context for children's argument production.
• Seven‐year‐olds are more strategic than five‐year‐olds in their reasoning with peers.
• Children's reasoning with others becomes more sophisticated after preschool years.

     

Families of Children With Attention-Deficit/Hyperactivity Disorder: Review and Recommendations for Future Research

This review integrates and critically evaluates what is known about family characteristics associated with childhood Attention-Deficit/Hyperactivity Disorder (ADHD). Evidence suggests that the presence of ADHD in children is associated to varying degrees with disturbances in family and marital functioning, disrupted parent–child relationships, specific patterns of parental cognitions about child behavior and reduced parenting self-efficacy, and increased levels of parenting stress and parental psychopathology, particularly when ADHD is comorbid with conduct problems. However, the review reveals that little is known about the developmental mechanisms that underlie these associations, or the pathways through which child and family characteristics transact to exert their influences over time. In addition, the influence of factors such as gender, culture, and ADHD subtype on the association between ADHD and family factors remains largely unknown. We conclude with recommendations regarding the necessity for research that will inform a developmental psychopathology perspective of ADHD.