Discrimination of response-reinforcer and response-stimulus contingencies in pigeons

For three pigeons (Experiment 1), the presentation of a red response key ended with a food presentation either following two responses separated by at least 10 seconds (a DRL contingency) or following a 10-second response-free period (a DRO contingency). For three other birds (Experiment 2), a brief stimulus presentation terminated the DRL and DRO contingencies. A white side key was presented next and ended with response-dependent food following one contingency and a timeout following the other. Since the contingency on the red key was unsignaled, differential responding on the white side key could indicate that the two response-reinforcer relations had been discriminated. In Experiment 1, the red-key duration and number of responses influenced white-key responding following the contingency that predicted the timeout. A response-initiated DRO was instated, and the influence of red-key duration and response number on white-key responding was diminished. In both experiments, the 10-second time criterion in both contingencies was varied from 0.34 second to 10 seconds. Even at short time intervals the DRO and DRL contingencies were readily discriminated. Pigeons tended to class the two contingencies according to a rule that did not involve simply stimulus duration, numbers of responses, or even the time between a response and its consequence.     

Walking through doorways causes forgetting: Event structure or updating disruption?

According to event cognition theory, people segment experience into separate event models. One consequence of this segmentation is that when people transport objects from one location to another, memory is worse than if people move across a large location. In two experiments participants navigated through a virtual environment, and recognition memory was tested in either the presence or the absence of a location shift for objects that were recently interacted with (i.e., just picked up or set down). Of particular concern here is whether this location updating effect is due to (a) differences in retention intervals as a result of the navigation process, (b) a temporary disruption in cognitive processing that may occur as a result of the updating processes, or (c) a need to manage multiple event models, as has been suggested in prior research. Experiment 1 explored whether retention interval is driving this effect by recording travel times from the acquisition of an object and the probe time. The results revealed that travel times were similar, thereby rejecting a retention interval explanation. Experiment 2 explored whether a temporary disruption in processing is producing the effect by introducing a 3-second delay prior to the presentation of a memory probe. The pattern of results was not affected by adding a delay, thereby rejecting a temporary disruption account. These results are interpreted in the context of the event horizon model, which suggests that when there are multiple event models that contain common elements there is interference at retrieval, which compromises performance.     

Sex differences in domain-specific depressogenic cognitive responses to negative and positive life events

Maladaptive cognitive responses to stressful life events represent well-replicated risk factors for depression. Research indicates that stressful life events that are dependent on the individual to occur or are interpersonal may generate more maladaptive cognitive responses than those that are independent and/or non-interpersonal. The current study examined the roles of sex and life event domains in eliciting depressogenic cognitive responses. Participants were 212 (71% female) undergraduate students who completed seven weekly questionnaires on participant-identified most negative and most positive life events over the previous 7 days. Additionally, participants reported levels of brooding and cognitive style in response to the most negative event and levels of positive rumination and dampening in response to the most positive event. Data were analyzed using mixed ANOVAs. Results indicated that females engaged in greater brooding regardless of event dependency. In addition, dependent and interpersonal life events generated greater brooding while dependent and non-interpersonal negative events generated greater negative cognitive style. An interaction between sex and domain was observed for dampening positive life events, such that males did not differ between interpersonal and non-interpersonal life events while females were more likely to dampen following interpersonal life events than non-interpersonal events.     

Recovery cycle of the evoked heart rate response in sleeping humans

Paired auditory stimuli, presented during sleep, evoked biphasic heart rate responses of greater than 10-second duration. The magnitude of the response to a second stimulus varies with the time between stimuli. The recovery cycle for human subjects exhibits a subnormal period for both HR peak and trough components at 5-or 6-second interstimulus intervals, and a supernormal period for the HR peak at 9-or 10-second interstimulus intervals. Thus, subnormal and supernormal periods coincide with the peak and trough, respectively, of the biphasic evoked heart rate response.     

学前儿童对短时时距的区分及其认知策略

本研究以令儿童比较时距长短为手段进一步探查学前（５、６岁）儿童对短时时距的认知过程,挖掘幼儿的认知潜力。研究结果表明：１）学前５、６岁儿童已能区分只有几秒钟差异的短时时距;２）６岁儿童已能使用时间标尺测量时间,５岁儿童已有潜力把时间看成是可以计数的维量;３）两时距的时间差别大小是影响儿童认知成绩的主要因素之一。     

Serial recall and presentation schedule: A micro‐analysis of local distinctiveness

According to temporal distinctiveness theories, items that are temporally isolated from their neighbours during presentation are more distinct and thus are recalled better. Event‐based theories, which deny that elapsed time plays a role at encoding, explain isolation effects by assuming that temporal isolation provides extra time for rehearsal or consolidation of encoding. The two classes of theories can be differentiated by examining the symmetry of isolation effects: Event‐based accounts predict that performance should be affected only by pauses following item presentation (because they allow time for rehearsal or consolidation), whereas distinctiveness predicts that items should also benefit from preceding pauses. The first experiment manipulated inter‐item intervals and showed an effect of intervals following but not preceding presentation, in line with event‐based accounts. The second experiment showed that the effect of following interval was abolished by articulatory suppression. The data are consistent with event‐based theories but can be handled by time‐based distinctiveness models if they allow for additional encoding during inter‐item pauses.     

Life events can trigger depressive exacerbation in the early course of schizophrenia

Previous studies have linked life events with depression in chronic schizophrenia, but those studies had methodological limitations. Using a prospective research design and examining events that were clearly independent of the patients' illnesses, the authors sought to determine whether stressful life events could trigger depressive symptoms in the early course of schizophrenia. Schizophrenia patients (n = 99) were followed for 1 year from a point of outpatient stabilization. Life event interviews were conducted every 4 weeks and symptom assessments every 2 weeks. Survival analyses showed a significantly increased risk for an exacerbation of significant depressive symptoms following an independent life event. Of interest is that an analysis of competing risk showed that the odds of psychotic exacerbation following a major independent life event were not significantly greater than the odds of depressive exacerbation. The risk of depression and of psychosis after experiencing a stressful life event is significantly increased for the first month, but the risk period can extend to 3 months.     

Schedule-induced locomotor activity in humans.

In two experiments, humans received tokens either on a fixed-interval schedule for plunger pulling or various response-nondependent fixed-time schedules ranging from 16 to 140 seconds. Locomotor activity such as walking, shifting weight, or pacing was recorded in quarters of the interreinforcement interval to examine the induced characteristics of that behavior in humans. While performance was variable, several characteristics were present that have counterparts in experiments with nonhumans during periodic schedules of food reinforcement: (a) first quarter rates, and sometimes overall rates, of locomotor activity were greater during intervals that terminated in a visual stimulus and token delivery than those without: (b) overall rates of locomotor activity were greater during fixed-time 16-second schedules than during fixed-time 80- or 140-second schedules; (c) rates of locomotor activity decreased during the interreinforcement intervals; (d) locomotor activity was induced by response-dependent and response-nondependent token delivery. These results showed that the rate and temporal pattern of locomotor activity can be schedule-induced in humans.     

Perceptions of stressful life events as turning points are associated with self-rated health and psychological distress

Abstract

We test the hypothesis that changes in physical and psychological health are associated with construals of stressful life events. At two points in time, approximately 10 years apart, participants (n=1038) rated their physical health and psychological distress. At the second assessment, participants also reported their most stressful life event since the first assessment and indicated whether they considered the event a turning point and/or lesson learned. Lower self-ratings of health and higher ratings of psychological distress, controlling for baseline health and distress, and relevant demographic factors, were associated with perceiving the stressful life event as a turning point, particularly a negative turning point. The two health measures were primarily unrelated to lessons learned. How individuals construe the most stressful events in their lives are associated with changes in self-rated health and distress.     

Free writing: Evaluation of a preventive program with elementary school children

Eight-session free-writing workshops focusing on developing elementary schoolchildren's use of different describing words, reference to self, expression and clarification of feelings, and expression of stress responses were introduced to 324 fifth-grade children living on the northern border of Israel where the probability of war-related crisis is particularly high. The purpose of the study was to evaluate (a) the effectiveness of the workshop and (b) the applicability of free writing in an actual stressful event. Results indicated that the workshop group exhibited higher mean scores than the nonintervention control group on all behavior measures, both after the workshop and following a stressful event (shelling of the town). The theoretical background for free-writing conceptualization is given and the implications of the results are discussed in light of large-scale preventive intervention.     

Time-course of eye movement-related decrease in vividness and emotionality of unpleasant autobiographical memories

The time-course of changes in vividness and emotionality of unpleasant autobiographical memories associated with making eye movements (eye movement desensitisation and reprocessing, EMDR) was investigated. Participants retrieved unpleasant autobiographical memories and rated their vividness and emotionality prior to and following 96 seconds of making eye movements (EM) or keeping eyes stationary (ES); at 2, 4, 6, and 10 seconds into the intervention; then followed by regular larger intervals throughout the 96-second intervention. Results revealed a significant drop compared to the ES group in emotionality after 74 seconds compared to a significant drop in vividness at only 2 seconds into the intervention. These results support that emotionality becomes reduced only after vividness has dropped. The results are discussed in light of working memory theory and visual imagery theory, following which the regular refreshment of the visual memory needed to maintain it in working memory is interfered with by eye movements that also tax working memory, which affects vividness first.     

Optokinetic stimulation affects temporal estimation in healthy humans

The representation of time and space are closely linked in the cognitive system. Optokinetic stimulation modulates spatial attention in healthy subjects and patients with spatial neglect. In order to evaluate whether optokinetic stimulation could influence time perception, a group of healthy subjects performed "time-comparison" tasks of sub- and supra-second intervals before and after leftward or rightward optokinetic stimulation. Subjective time perception was biased by the direction of optokinetic stimulation. Rightward optokinetic stimulation induced an overestimation of time perception compared with baseline and leftward optokinetic stimulation. These results indicate a directional bias in time perception induced by manipulation of spatial attention and could argue for a mental linear representation of time intervals.     

Fixed-ratio discrimination: effects of intermittent reinforcement

Four pigeons had discrimination training that required the choice of a left side-key after completing a fixed-ratio 10 on the center key, and a right side-key choice after fixed-ratio 20. Correct choices were reinforced on various fixed-interval, fixed-ratio, random-interval, and random-ratio schedules. When performance was examined across successive 15-second intervals (fixed-interval and fixed-ratio schedules) accuracy was high in the first 15-second interval, decreased in one or several of the next 15-second intervals, and then increased again as reinforcement was approached. When performance was examined across correct trials on fixed-interval and fixed-ratio schedules, accuracy was lowest immediately after reinforcement, followed by a systematic increase in accuracy as the number of correct choices increased. These patterns were due primarily to errors on fixed-ratio 20 trials. Systematic accuracy patterns did not occur on random-interval or random-ratio schedules. The results indicate that when choice patterns differed on fixed-interval and fixed-ratio schedules, the differences were due to the method of data analysis.     

An Investigation of the Efficacy of Online Expressive Writing for Trauma-Related Psychological Distress in Hispanic Individuals

This study compared the efficacy of 2 online expressive writing protocols for a traumatic/stressful life event in a Hispanic student sample. Participants who had reported a traumatic event were randomly assigned to either the emotion-focused group or the fact-focused group. The emotion-focused group focused their written accounts on emotions and feelings as well as facts about a stressful/traumatic experience, whereas the fact-focused group focused on facts of a stressful/traumatic event. Both groups completed 3 online writing sessions scheduled for 3 consecutive days, a 1-week online follow-up assessment, and a 5-week online follow-up assessment. Both groups statistically significantly reduced trauma symptoms over time with the emotion-focused group demonstrating statistically significantly greater trauma symptom reductions than the fact-focused group at the 5-week follow-up assessment.     

A lengthy look at the daily grind: time series analysis of events, mood, stress, and satisfaction

The present study investigated processes by which job stress and satisfaction unfold over time by examining the relations between daily stressful events, mood, and these variables. Using a Web-based daily survey of stressor events, perceived strain, mood, and job satisfaction completed by 14 university workers, 1,060 occasions of data were collected. Transfer function analysis, a multivariate version of time series analysis, was used to examine the data for relationships among the measured variables after factoring out the contaminating influences of serial dependency. Results revealed a contrast effect in which a stressful event associated positively with higher strain on the same day and associated negatively with strain on the following day. Perceived strain increased over the course of a semester for a majority of participants, suggesting that effects of stress build over time. Finally, the data were consistent with the notion that job satisfaction is a distal outcome that is mediated by perceived strain.     

Enhancing attributional style as a resiliency factor in depressogenic stress generation

Abstract

There is a growing body of evidence that suggests depression and cognitive vulnerabilities to depression may lead individuals to generate stressful events. However, there has been no study to date that has directly examined factors that may lead individuals to be less likely to generate stressful events. The present study examines whether an enhancing attributional style, the tendency to make global and stable inferences following occurrence of a positive event, functions as a resiliency factor in stress generation. One hundred and sixty-seven female students completed measures of depression symptoms and attributional style at baseline and occurrence of life events since baseline at a four-week follow-up. Results indicated that an enhancing attributional style predicted decreased levels of stressful events over the following four weeks, even when controlling for depression symptoms. The findings of this study suggest that there may be resiliency factors that can help protect individuals from the generation of stressful events.     

Perfectionism Cognitions, Rumination, and Psychological Distress

The current study examined the extent to which dimensions of perfectionism are associated with a ruminative response orientation and the experience of cognitive intrusions in response to stressful events. Our main goal was to test the hypothesis that individuals characterized by frequent automatic thoughts involving perfectionistic themes would also be characterized by a ruminative response orientation when distressed and they would report intrusive thoughts and images following the experience of a stressful event. A sample of 65 students completed several measures, including the Perfectionism Cognitions Inventory, the Multidimensional Perfectionism Scale, the Response Styles Questionnaire, the Impact of Events Scale, and indices of depression and anxiety. Correlational analyses confirmed that high scores on the Perfectionism Cognitions Inventory were correlated with a ruminative response orientation and the reported experience of intrusive thoughts and images following the experience of a stressful event. High levels of perfectionism cognitions, socially prescribed perfectionism, and rumination were also correlated with measures of depression and anxiety representingthe tripartite model. The results support the view that there is a salient cognitive aspect to perfectionism and the experience of frequent perfectionistic cognitions and related forms of rumination contribute to levels of psychological distress.     

Choosing between predictable shock schedules: Long- versus short-duration signals

Two experiments assessed the relative aversiveness of different duration preshock signals (5 and 20 seconds) and different duration stimuli identifying shock-free periods. In the first experiment, the responding of 15 of 18 rats was maintained when it produced changes from a predictable-shock condition with a 5-second preshock signal to an identical schedule with a 20-second preshock signal; responding was not maintained when it produced the opposite changes. These results occurred with intershock intervals of both 120 seconds and 240 seconds. The second experiment assessed whether changing to the 20-second schedule was maintained by properties of the preshock signals identifying the shock periods or by properties of the stimuli identifying the shock-free periods. Four subjects were given training with the two signaled schedules in an operant chamber and then later given off-baseline preference tests in a shuttlebox. When given a choice between preshock signals, subjects chose the 5-second signals over the 20-second signals. However, when given a choice between stimuli identifying shock-free periods, subjects chose the stimulus identifying the shorter shock-free periods (i.e., the one previously correlated with the 20-second signals). These findings are discussed within the Rescorla and Wagner model of stimulus compounds and within the context of safety as a contrast phenomenon.     

Variable shock-free times with informative and uniformative stimuli

Three rats were trained on a fixed-ratio escape procedure in which responding produced one of two equiprobable outcomes—a 10-second or 60-second shock-free period. Before the fixed-ratio requirement was satisfied, brief shocks were presented at irregular intervals averaging either 15 or 30 seconds. Two conditions, differing in the relationship between exteroceptive stimuli and the outcomes, were studied. In the uninformative (uncorrelated) condition, the same stimulus was presented during both outcomes. In the informative (correlated) condition, one stimulus was present during the 10-second outcome only; another stimulus was present during the 60-second outcome only. Subjects pressed faster in the uninformative condition than they did in the informative condition. The inadequacy of the information hypothesis in accounting for the findings is discussed, and an alternative hypothesis is offered.