The role of segmental mass and moment of inertia in dynamic-contact task construction

The authors examined whether differences between children and adults in the application of muscle forces during a dynamic-contact task (cycling) can be attributed to children's relatively lower segmental mass and moment of inertia. They examined pedal-force construction as adults and younger and older children (n = 7 in each group), with and without mass added to their limbs, pedaled an appropriately scaled bicycle ergometer. When mass was added to their limbs, children adjusted muscular forces on the pedal in a way that began to approach the pattern demonstrated by adults. Because age, neuromotor maturation, and motor experience were held constant, it seems plausible that by 6 to 8 years of age, and perhaps younger, physical size and growth limit children's production of adult-like muscle forces on the pedal.     

The role of offer rates in controlling sharing by young children

The effects of different reinforcement contingencies on the rates of offers to share and their corresponding rates of acceptance by two small groups of preschool children were investigated in two experiments. In the first experiment, food and praise were given after a 5-min play period to any subject who had made one or more offers to share during the play period. This procedure increased the rate of share-offers by all subjects. However, as share-offers increased, the percentage of offers accepted decreased. In the second experiment, reinforcement was made contingent on a subject reducing offers to share to only one or two per 5-min period. This led to a higher percentage of the offers being accepted. The results suggest that by controlling the rate of a social behavior, the manner in which other persons in the environment respond to the behavior may also be influenced.     

Changes in mood caused by staged, moderate physical activity]

This experiment provides a test for the common sense knowledge that moderate physical exercise leads to mood improvement. Furthermore, it was tested whether light exercise intensifies negative feeling states or alleviates them. 30 female and 30 male students of psychology served as subjects (mean age 25.3 years, SD = 4.8). After being exposed to a mood induction procedure designed to elicit either a positive or negative feeling state, the subjects had to pedal a bicycle ergometer with 0, 50 or 75 Watt load. Cardiovascular variables and self-reports of mood states were assessed during a baseline period, after the mood induction, following the ergometer exercise, and after a follow-up period. The mood induction procedures were successful, but only for a short duration. Physiological activation was observed according to the ergometer loadings. Moderate physical exercise led to an increase of positive feeling states (Concentration) and a decrease of negative feeling states (Tiredness) in the follow-up period. Corresponding changes in tension related states could not be observed, probably due to the weakness of the mood induction procedure employed and the low level of energetic activation reached.     

Schedule-induced licking during multiple schedules

Schedule-induced polydipsia was studied in rats bar pressing under two-component multiple schedules of food reinforcement. The first component of the multiple schedule was a variable-interval 1-min schedule throughout the experiment. The schedule comprising the second component was varied over blocks of sessions in terms of rate and magnitude of reinforcement, and was either variable-interval 3-min (one pellet), variable-interval 3-min (three pellets), variable-interval 1-min (one pellet), or extinction. Water intake per session varied with the rate of reinforcement in the schedule comprising the second component and was highest when the schedule was variable-interval 1-min. Both bar-pressing behavior and licking behavior showed behavioral interactions between the two components of the multiple schedules. With magnitude of reinforcement held constant, a matching relationship was observed between lick rate and reinforcement rate; the relative frequency of licks in the constant component matched the relative frequency of reinforcement in that component. Bar pressing, however, showed only a moderate degree of relativity matching. During the schedule-induced licking, a burst of licking followed each delivery of a pellet (post-prandial drinking). The duration of these bursts of licking was observed to be a function of the inter-reinforcement interval.     

Influence of traffic conditions on driver behavior before making a right turn at an intersection: Analysis of driver behavior based on measured data on an actual road

This paper describes an investigation of the influence of the position of a forward vehicle and following vehicle on the onset of driver preparatory behavior before making a right turn at an intersection. Four experimental vehicles with various sensors and a driving recorder system were developed to measure driver behavior before making a right turn at a specific intersection on a public road. The experimental term was eight weeks to collect data on natural driving maneuvers. The relationships between the remaining distances to the center of the intersection when releasing the accelerator pedal, moving the right foot to cover the brake pedal, and activating the turn signal and the relative distances from the forward and following vehicles were analyzed based on the measured data. The time it took to reach the center of the turn and the driving speed when each behavioral event occurred were also evaluated from the viewpoint of the relative position between the driver’s vehicle and the leading or following vehicles. The results suggest that the drivers approached the target intersection in a car-following condition, and that the positions of the front and rear vehicles and the vehicle velocity influence the onset location and timing of releasing the accelerator pedal and covering the brake pedal. Drivers began to decelerate closer to the center of the intersection when they approached the intersection close to a leading or following vehicle at a reduced driving speed. However, these influences were not reflected in the turn signal operation, indicating that drivers intend to make a right turn at a constant location while approaching a target intersection and that intention appears in the turn signal activation. The findings of this observational study imply that the method of providing route guidance instruction, in which the traffic conditions surrounding the driver’s vehicle are taken into consideration, is effective in reducing driver errors in receiving instruction and following the correct route. The results also indicate that measuring and accumulating different behavioral indices based on traffic conditions contribute to determining the criteria for the presentation timing just before reaching the intersection, which can assist drivers in preparing to make a right turn at a usual location. Driver decelerating maneuvers are used while driving without leading or following vehicles and while driving with a lead and/or following vehicle at long range, and driver turn signal operations are used when approaching an intersection under close car-following conditions.     

Reinforcement delay: some effects on behavioral contrast

Thirty five White Carneaux pigeons first received 20 sessions of non-delayed reinforcement according to a multiple variable-interval 1-min variable-interval 1-min schedule. For the remaining 15 sessions, subjects were assigned to one of five groups, with seven subjects per group. Four of these groups involved reinforcement according to the same multiple schedule as before, but reinforcement during one of the components was delayed for either 2.5, 5, 10, or 120 sec. The schedule for the fifth group was changed to multiple variable-interval 1-min extinction schedule of reinforcement. While some subjects in all groups showed behavioral contrast, it occurred more consistently in the groups involving extinction or the longer delays of reinforcement. Groups involving the various durations of delayed reinforcement or even extinction during the altered component did not, however, show a statistically significant difference in the amount of behavioral contrast. It was suggested that neither a reduction in reinforcement frequency nor response rate during the altered component is necessary to the production of behavioral contrast.     

Response suppression produced by vestibular stimulation in the rat

Seven rats were trained to stable performance levels on either Fixed Ratio 47, Variable Ratio 47, Variable Interval 1-min, or Fixed Interval 1-min schedules of food reinforcement. Subjects were then tested for sensitivity to vestibular stimulation from rotation, using an ascending method of limits technique with increments in velocity of one revolution per minute every 5 min. Centrifugal forces were minimized by locating the test chamber over the axis of rotation. Response rates decreased in all subjects as a function of increasing rotation speed. In addition, characteristic differences in the patterns of response decrement were found between subjects on ratio and on interval schedules. Repeated tests indicated high intra-subject reliability in sensitivity to rotation. Similarities of these data to "motion sickness" phenomena in other species were noted. It is suggested that this behavioral approach provides a sensitive and quantifiable technique for assessing the effects of vestibular stimulation in animals.     

Tolerance to cocaine's rate-increasing effects upon repeated administration.

Four squirrel monkeys responded daily under a fixed-interval 5-min or 8-min schedule of food-pellet delivery. Cocaine (0.03 to 1.7 mg/kg) and saline were injected before occasional daily sessions (acute administration). Some doses of cocaine produced substantial overall increases in response rate for 3 of the subjects; effects were less substantial for the remaining subject, who exhibited modest increases in response rate early in the session and during the middle portion of the intervals. A dose that increased response rate when administered acutely was then administered before each session (chronic administration). Chronic administration resulted in a reduction in the increases in response rate seen under acute administration for all subjects.     

Attraction and altruism: With a little help from my friends

The present experiment was designed to determine whether the reinforcement value of an altruistic response is a function of attraction toward the victim and/or the affective state of the subject. Subjects (N = 95) received positive or negative evaluations from a victim or from a bystander and subsequently performed an altruistic response which terminated shock delivery to a victim on a series of 14 trials. Analyses of variance indicated that the acquisition of an altruistic response was greatest when attraction toward the victim was most positive (p < .0001) and nonexistent when attraction toward the victim was least positive. The results were consistent with the proposition that attraction rather than affect mediates altruistic reinforcement. Those subjects receiving negative evaluations from the victim failed to acquire the altruistic response, suggesting that failure to help may function as a form of passive aggression.     

Influence of aerobic fitness on ratings of perceived exertion during light to moderate exercise

Based on scores from a maximal exercise test on a bicycle ergometer, 24 college-age women were classified into three aerobic-fitness groups. Each subject then completed two randomly ordered cycle exercise bouts at 1-wk. intervals. The exercise bouts required the subjects to pedal for 24 min. attaining and then maintaining a target heart rate of either 30% or 60% of heart-rate reserve. Ratings of perceived exertion (RPE) were reported at the end of each third minute of the exercise period. Repeated-measures analysis of variance indicated the RPE was significantly related to the exercise workload and duration of exercise. No main effect was found for fitness. Two-way interactions were detected for fitness x duration of exercise and for workload x duration of exercise.     

Effects of passive physical exercise on peripheral vision in muscular dystrophic children

To investigate the effects of passive exercise of the extremities on peripheral vision of muscular dystrophic children aged 9 to 13 yr. these subjects were either not exercised (control days) for a 6-min. period or were exercised (experimental days) for a 6-min. period after a 5-min. rest. Peripheral vision was recorded after each condition. Analysis of variance with repeated measures on the exercise and no exercise conditions was computed for each measure. 6 min. of passive exercise significantly increased peripheral vision. It was assumed that exercise increased blood flow through the lungs allowing for greater oxygen diffusion in the brain and other facilitory responses which increased effective cerebral activity. Curriculum revisions for such children indicate the importance of activity in facilitating subsequent learning.     

Behaviour of ‘impulsive’ and ‘non-impulsive’ humans in a temporal differentiation schedule of reinforcement

The operant behaviour of psychometrically defined ‘impulsive’ and ‘non-impulsive’ subjects, under a temporal differentiation schedule of reinforcement, was examined. Four impulsive and four non-impulsive females were selected on the basis of their scores on the Matching Familiar Figures Test. The subjects participated in fifteen 45-min sessions in which they were exposed to an inter-response-time-greater-than-10-sec schedule of monetary reinforcement. During Phase I (sessions 1–5) no information was provided about the reinforcement contingency. During Phase II (sessions 6–10) a light on the response panel was illuminated whenever a reinforcer became available. At the start of Phase III (session 11) the subjects were given explicit information about the reinforcement contingency. At the start of Phase IV (sessions 12–15) the subjects were told that the light would no longer be operative although the contingency would remain unaltered. During Phase I the impulsive subjects earned fewer reinforcers, and emitted a greater proportion of non-reinforced responses (inter-response times less than 10 sec) than the non-impulsive subjects. During Phase II both groups increased their earnings, although the performance of the non-impulsive group remained superior to that of the impulsive group. In Phase III both groups performed equally well. In Phase IV the performance of both groups deteriorated, the impulsive group performing more poorly than the non-impulsive group. The results demonstrate the sensitivity of operant performance maintained under temporal differentiation schedules to personality dimensions such as ‘impulsiveness/non-impulsiveness’.     

Stimulus generalization and delay of reinforcement during one component of a multiple schedule

The key pecking of six pigeons was reinforced according to a variable-interval 1-min schedule during each of two successively presented stimuli. When the key was illuminated by a black line on a white background, reinforcement was delayed for 10 sec. When the key was illuminated by a plain white light, reinforcement was not delayed. All subjects responded at a lower rate during the presentation of the black line. A subsequent generalization test along the line-orientation dimension produced a U-shaped gradient, with the nadir located at or near the training stimulus, for each subject. These gradients suggested that the lower rate of response during the stimulus associated with delayed reinforcement may have been due to an inhibition of responding.     

Saving mental effort to maintain physical effort: a shift of activity within the prefrontal cortex in anticipation of prolonged exercise

Executive functioning and attention require mental effort. In line with the resource conservation principle, we hypothesized that mental effort would be saved when individuals expected to exercise for a long period. Twenty-two study participants exercised twice on a cycle ergometer for 10 min at 60% of their maximal aerobic power, with the expectation of exercising for either 10 min or 60 min. Changes in activity in the right dorsolateral prefrontal cortex (rdlPFC) and right medial frontal cortex (rmPFC) were investigated by measuring oxyhemoglobin using near-infrared spectroscopy. Attentional focus and ratings of perceived exertion were assessed at three time points (200, 400, and 600 s). The oxyhemoglobin concentration was lower in the rdlPFC and higher in the rmPFC under the 60-min than under the 10-min condition. Also, attention was less focused in the 60-min than in the 10-min condition. We discuss these results as possible evidence of a disengagement of the brain regions associated with mental effort (executive network), in favor of brain regions linked to resting activity (the default network), in order to save mental resources for the maintenance of exercise.     

EFFECTS OF MEMORY AIDS ON THE DYADIC CONVERSATIONS OF INDIVIDUALS WITH DEMENTIA

The effects of a prosthetic memory aid on the conversational content and social skills of dyads with dementia were evaluated. Six individuals with moderate to severe dementia served as either subject or partner in dyads during 5-min conversational probes conducted three times per week in daycare and nursing-home settings. During phases when a memory aid, consisting of personally relevant picture and sentence stimuli, was available, most subjects used their own aid to improve the quality of conversations by increasing the frequency of on-topic statements, diminishing nonproductive utterances, lengthening their conversational turn, and/or increasing the frequency of turns taken. Most partners demonstrated awareness of social discourse conventions by appropriately relinquishing conversational dominance, decreasing both content and nonproductive utterances, and increasing acknowledging or affirmative comments when subjects used memory aids. Naive judges' ratings of aided and unaided conversational samples on seven conversational dimensions reflected differences in perceptions of significant improvement as a function of the conversational discourse style of each dyad.     

Shaping avoidance behavior in restrained monkeys

Lever-pulling avoidance behavior of 24 monkeys was actively shaped with a manual shock-control box and a closed-circuit TV system. A negative reinforcement procedure was used wherein a periodically occurring body shock was postponed each time the subject moved toward the lever. All subjects were trainable with this method, two-thirds of them in fewer than five, 1- to 2-hr sessions. Negative reinforcement was more effective than a punishment procedure.     

Modeling and prediction of driver preparations for making a right turn based on vehicle velocity and traffic conditions while approaching an intersection

This paper focuses on modeling and predicting the influence of a vehicle’s velocity and the relative position between a driver’s vehicle and a vehicle to the front or rear on the onset of driver preparations for making a right turn at an intersection. Repeated experiments were carried out on a public road to measure driver preparations, including releasing the accelerator pedal, moving the right foot to cover the brake pedal, and activating the turn signal, as well as to record vehicle velocity and the relative distances to the leading and following vehicles. Structural equation modeling was applied to estimate these relationships quantitatively. Two separate latent variables accounting for the interaction between the driver’s vehicle and leading or following vehicles, and the onset point where driving behavior changes from straight mode to preparation mode before a right turn, were introduced in the specification of the structural equation model. The model estimates and testing indicate that the proposed structural equation model represents well the relationship hypothesized by observational analysis: that the vehicle velocity and the traffic conditions surrounding the driver’s vehicle strongly influence the driver’s deceleration and more weakly influenced turn signal activation. The proposed structural equation model contributes to the prediction of the onset locations of covering the brake pedal and activating the turn signal based on the vehicle velocity and the relative distances to the front and rear vehicles when the accelerator pedal is released. The prediction accuracy is high compared with predictions in which the vehicle velocity and the headway or rear distances are not taken into account or predictions using a single regression model with one independent variable, namely driving speed. Finally, a possible new addition to in-vehicle navigation systems that detects unusual driver behavior by predicting the driver’s preparatory maneuvers is discussed.     

Efficacy and feeling of a vibrotactile Frontal Collision Warning implemented in a haptic pedal

A haptic pedal has been designed to emulate the behaviour of a common vehicle pedal and render superimposed vibrations with different characteristics. It was installed in a driving simulator, as an accelerator pedal with the secondary function of a vibrotactile Frontal Collision Warning (FCW). The efficacy and feeling of this solution was tested with 30 subjects using vibrotactile signals with 0.50, 1.05, and 1.60 Nm, at 2.5, 5, and 10 Hz, against a baseline visual FCW. Participants had to match the speed of a leading vehicle when the FCW was triggered. Their braking response was evaluated in terms of brake reaction time, matching speed time, control of velocity and headway reduction. Driver’s feelings were assessed with Kansei methodologies. Haptic stimuli were found to be more effective than visual signals, and the characteristics of the vibration also influenced the results. The best performance was achieved at the maximum amplitude, and in the range between 5 and 10 Hz. The perceived functionality and discomfort followed a trend coherent with the objective measurements. The conclusions of this study may be applied to develop effective and safe warning systems in vehicles, limiting the annoyance that they might cause to drivers.     

Response-reinforcer relations and the maintenance of behavior

The effects on pigeons' key pecking of unsignaled delays of reinforcement and response-independent reinforcement were compared after either variable-interval or differential-reinforcement-of-low-rate baseline schedules. One 30-min session arranging delayed reinforcement and one 30-min session arranging response-independent reinforcement were conducted daily, 6 hr apart. A within-subject yoked-control procedure equated reinforcer frequency and distribution across the two sessions. Response rates usually were reduced more by response-independent than by delayed but response-contingent delivery of reinforcers. Under both schedules, response rates were lower when obtained delays were greater. These results bear upon methodological and conceptual issues regarding comparisons of contingencies that change the temporal response–reinforcer relations.