Agoraphobic avoidance and panic frequency as predictors of laboratory induced panic reactions

This study examined the importance of agoraphobic avoidance and frequency of panic as predictors of psychological and physiological responses of panic sufferers to a laboratory based provocation procedure. Psychophysiologic comparisons were made between 22 panic disorder patients and 15 controls, at baseline and across three periods of carbon dioxide gas inhalations (1, 3, 5%; balance oxygen). Subjective measures of anxiety, frightening cognitions and body sensations were obtained across the phases. Physiological measures of minute ventilation, breathing rate, tidal volume, end tidal CO₂ and heart rate were also obtained. Between group comparisons revealed significant differences between the groups on the subjective measures with no significant differences occurring on the physiological measures. Within group analyses revealed that pre-session questionnaire measures of agoraphobia avoidance and panic frequency predicted the degree of anxiety, frightening sensations and cognitions during baseline and 5% CO₂ inhalation. The results indicated that both self-reported agoraphobic avoidance and panic frequency are strong clinical predictors of psychological reactions of panic sufferers during laboratory provocation.     

Conditioned hyperventilation as a factor in animal, infant, and adult apnea: a theoretical analysis of experimental and clinical data

An apnea hypothesis is proposed termed Conditioned Hyperventilation. An organism (animal, infant, or adult) can become conditioned to anticipate traumatic terminal breathing. The resulting hyperventilation produces excessive oxygen, which triggers apnea, allowing an increase in carbon dioxide. This apnea serves as an additional unconditioned stimulus (UCS) causing the hyperventilation (apnea) to increase. Organic blockage can also serve as the UCS. Apnea may be reduced or prevented by monitoring and extinguishing hyperventilation through the use of behavioral modification techniques, or biofeedback. Infant lung collapse during the first six months is suggested as one UCS in infants.     

Validity and reliability of a Cantonese-translated rating of perceived exertion scale among Hong Kong adults

This study assessed the validity and reliability of the Cantonese-translated version of the Borg 6-20 Rating of Perceived Exertion (RPE) scale during continuous incremental cycle ergometry by Hong Kong adults. A total of 54 participants (25 males and 29 females), ages 22.2 +/- 4.7 yr., volunteered to participate. They performed two trials of identical continuous incremental cycling exercise 1 wk. apart for the reliability test. The objective measures of exercise intensity (heart rate, power output, and oxygen consumption) and the subjective measure of effort (RPE) were obtained during the incremental exercise. Significant (p < .01) Pearson correlations were found when RPE values were correlated with heart rate (rs > or = .73), power output (rs > or = .69), and oxygen consumption (rs > or = .68). The overall test-retest intraclass correlation (R = .92) indicated that the scale was reliable. In conclusion, this Cantonese scale for rating of perceived exertion appears to be a valid and reliable psychophysiological tool to measure perceptions of exertion during controlled cycle ergometer exercise by Hong Kong adults.     

Change over training sessions of relationship between locus of control and voluntary heart-rate control.

The present study investigated the effects of locus of control on learning to accelerate and decelerate heart over a number of training sessions. 15 Ss who scored internal in locus of control and 15 who scored external were trained to change their heart rates. Ss were given two training sessions in speeding heart rate and two in slowing heart rate. Results indicated that during the initial training sessions, internals were better able to increase their heart rates than externals; the externals were better able to decrease their heart rates than internals. However, this association diminished to nonsignificance when additional training sessions were provided. These results argue for routinely conducting a number of training sessions to avoid any premature statement of a relationship between personaltiy measures and learned control of heart rate.     

Approximate entropy and point correlation dimension of heart rate variability in healthy subjects

The contribution of nonlinear dynamics to heart rate variability in healthy humans was examined using surrogate data analysis. Several measures of heart rate variability were used and compared. Heart rates were recorded for three hours and original data sets of 8192 R-R intervals created. For each original data set (n=34), three surrogate data sets were made by shuffling the order of the R-R intervals while retaining their linear correlations. The difference in heart rate variability between the original and surrogate data sets reflects the amount of nonlinear structure in the original data set. Heart rate variability was analyzed by two different nonlinear methods, point correlation dimension and approximate entropy. Nonlinearity, though under 10 percent, could be detected with both types of heart rate variability measures. More importantly, not only were the correlations between these measures and the standard deviation of the R-R intervals weak, the correlation among the nonlinear measures themselves was also weak (generally less than 0.6). This suggests that in addition to standard linear measures of heart rate variability, the use of multiple nonlinear measures of heart rate variability might be useful in monitoring heart rate dynamics.     

Psychophysiological assessment during exposure in driving phobic patients

A comprehensive assessment of fear or anxiety requires measurement of both self-report and physiological responses. Respiratory abnormalities have been rarely examined during real-life exposure, although they are an integral part of fear. Twenty-one women with a specific driving phobia and 17 nonphobic women were psychophysiologically monitored during 2 highway-driving sessions; phobic women completed an additional session. Respiratory movements, end-tidal partial pressure of carbon dioxide, an electrocardiogram, skin conductance, and skin temperature were recorded. Phobic patients differed from control participants both physiologically and experientially before, during, and after exposure. Effect size during exposure was large for the authors' measure of hyperventilation. Discriminant analysis indicated that multiple physiological measures contributed nonredundant information and correctly classified 95% of phobic and control participants. Thus, selected respiratory and autonomic measures are valid diagnostic and therapeutic outcome criteria for this situational phobia.     

Food‐related risk‐reduction strategies: purchasing and consumption processes

Confronted with an alarming social discourse favouring the perception of food risk, modern consumers find themselves in a situation of psychological discomfort caused by consumption of foodstuffs coming from the agricultural and foodstuff industry. To eliminate this discomfort the consumer may change their purchasing and consumption habits (constraining hypothesis) or introduce some measures for the reduction of risk. The aim of this paper is to present a new classification of risk reducers taking into account the diversity of buying and consumption practices. Copyright © 2004 Henry Stewart Publications.     

Intention to change activities that reduce carbon dioxide emissions related to worry about global climate change consequences

IntroductionMitigating the global climate change requires actions at different levels including that lay people change their consumption patterns, which cause emissions of greenhouse gases. Recent research suggests that inducing affects such as fear and worry may have positive effects.ObjectiveTo investigate whether worry in addition to personalized information about emissions of carbon dioxide would influence lay people's intentions to change consumption-related personal activities causing carbon-dioxide emissions.MethodA municipality-provided tool to calculate their annual carbon dioxide emissions was used by 135 university students who after being informed about negative consequences of global climate change stated their intentions to change a number of personal activities to reduce carbon dioxide emissions during the following 12 months. They also rated how worried they were about eight global climate change consequences.ResultsIntentions to change travel, energy use at home, food consumption, involvement in environmental organizations, and support of environmental policies increased with worry. An interaction was also observed such that high-emitters’ intentions to invest in energy-efficient infrastructure increased more with worry than did low- and medium-emitters’ intentions.ConclusionsIn line with recent research positing that affect increases preventive actions, the hypothesis was supported that intentions to change personal activities to reduce carbon dioxide emissions increased with participants’ worry about the consequences of global climate change.     

Nocturnal panic: response to hyperventilation and carbon dioxide challenges

To examine the role of ventilatory response in nocturnal panic, subjects experiencing nocturnal panic were compared with those who experienced daytime panic attacks only. In particular, measures of chronic hyperventilation (baseline pCO2) and CO2 hypersensitivity (response to ventilatory challenges) were assessed. Subjective and psychophysiological measures were obtained during baseline, forced hyperventilation, and carbon dioxide inhalation phases of a standardized laboratory-based assessment. The groups did not differ with respect to subjective or physiological measures or to the frequency with which panic occurred during the assessment. The results do not lend support to models that emphasize central CO2 hypersensitivity and chronic hyperventilation as primary mechanisms underlying nocturnal panic.     

Approximate entropy and point correlation dimension of heart rate variability in healthy subjects.

The contribution of nonlinear dynamics to heart rate variability in healthy humans was examined using surrogate data analysis. Several measures of heart rate variability were used and compared. Heart rates were recorded for three hours and original data sets of 8192 R-R intervals created. For each original data set (n = 34), three surrogate data sets were made by shuffling the order of the R-R intervals while retaining their linear correlations. The difference in heart rate variability between the original and surrogate data sets reflects the amount of nonlinear structure in the original data set. Heart rate variability was analyzed by two different nonlinear methods, point correlation dimension and approximate entropy. Nonlinearity, though under 10 percent, could be detected with both types of heart rate variability measures. More importantly, not only were the correlations between these measures and the standard deviation of the R-R intervals weak, the correlation among the nonlinear measures themselves was also weak (generally less than 0.6). This suggests that in addition to standard linear measures of heart rate variability, the use of multiple nonlinear measures of heart rate variability might be useful in monitoring heart rate dynamics.     

Concurrent measurement of heart rate and instrumental avoidance behavior in the Rhesus monkey

A graphical method has been developed for the concurrent recording of heart beats and lever responses during behavioral experiments. The EKG signal fed into any DC amplifier goes to a fixed level trigger circuit and relay driver with its own power supply. The signal from this drives any standard cumulative recorder. Lever response rates are recorded concurrently on an additional cumulative recorder using the same paper speed.     

Effects of reinforcer consumption and magnitude on response rates during noncontingent reinforcement

Results of previous research on the effects of noncontingent reinforcement (NCR) have been inconsistent when magnitude of reinforcement was manipulated. We attempted to clarify the influence of NCR magnitude by including additional controls. In Study 1, we examined the effects of reinforcer consumption time by comparing the same magnitude of NCR when session time was and was not corrected to account for reinforcer consumption. Lower response rates were observed when session time was not corrected, indicating that reinforcer consumption can suppress response rates. In Study 2, we first selected varying reinforcer magnitudes (small, medium, and large) on the basis of corrected response rates observed during a contingent reinforcement condition and then compared the effects of these magnitudes during NCR. One participant exhibited lower response rates when large-magnitude reinforcers were delivered; the other ceased responding altogether even when small-magnitude reinforcers were delivered. We also compared the effects of the same NCR magnitude (medium) during 10-min and 30-min sessions. Lower response rates were observed during 30-min sessions, indicating that the number of reinforcers consumed across a session can have the same effect as the number consumed per reinforcer delivery. These findings indicate that, even when response rate is corrected to account for reinforcer consumption, larger magnitudes of NCR (defined on either a per-delivery or per-session basis) result in lower response rates than do smaller magnitudes.     

Quality circles in a unionized setting: Their effect on grievance rates

This study examined the effect of quality circles (QCs) on grievance rates in a unionized manufacturing plant. Because circles are designed to give employees additional influence over their work lives, it was hypothesized that QC participation would reduce the number of grievances filed by circle members. This hypothesis was tested with 166 employees at a large manufacturing plant using a repeated measures control group design. Grievance rates of QC members and nonmember control employees were monitored over a three-year period, from 12 months before to 24 months after circle implementation. A significant decline in circle members' grievance rates was observed for the first post-implementation year and remained stable during the following year. It was also found that QC members filed over two-thirds of all grievances throughout the entire three year measurement period. Alternative explanations for the findings are discussed, as well as their implications for cooperative labor-management relations.An earlier version of this paper was presented at the 98th Annual Convention of the American Psychological Association at Boston, August 10, 1990.     

Attentional bias to emotional stimuli is altered during moderate- but not high-intensity exercise

Little is known regarding how attention to emotional stimuli is affected during simultaneously performed exercise. Attentional biases to emotional face stimuli were assessed in 34 college students (17 women) using the dot-probe task during counterbalanced conditions of moderate- (heart rate at 45% peak oxygen consumption) and high-intensity exercise (heart rate at 80% peak oxygen consumption) compared with seated rest. The dot-probe task consisted of 1 emotional face (pleasant or unpleasant) paired with a neutral face for 1,000 ms; 256 trials (128 trials for each valence) were presented during each condition. Each condition lasted approximately 10 min. Participants were instructed to perform each trial of the dot-probe task as quickly and accurately as possible during the exercise and rest conditions. During moderate-intensity exercise, participants exhibited significantly greater attentional bias scores to pleasant compared with unpleasant faces (p < .01), whereas attentional bias scores to emotional faces did not differ at rest or during high-intensity exercise (p > .05). In addition, the attentional bias to unpleasant faces was significantly reduced during moderate-intensity exercise compared with that during rest (p < .05). These results provide behavioral evidence that during exercise at a moderate intensity, there is a shift in attention allocation toward pleasant emotional stimuli and away from unpleasant emotional stimuli. Future work is needed to determine whether acute exercise may be an effective treatment approach to reduce negative bias or enhance positive bias in individuals diagnosed with mood or anxiety disorders, or whether attentional bias during exercise predicts adherence to exercise.     

Metabolic costs of aggressive behaviour in the Siamese fighting fish,Betta splendens

Aggressive conflicts between males are often resolved by means of multiple ritualized agonistic displays without damaging escalation. Apparently, in such cases by using those displays opponents exchange important motivational and physical information on which they base a decision to stay or leave the interaction. In the Siamese fighting fish, the time spent spreading the dorsal fin and erecting the gill coverts predicts who will be the winner or loser of the interaction. Two experiments were carried out to study whether display performance might be costly. First, oxygen consumption was measured during mirror‐image stimulation. This experiment showed that oxygen consumption was positively correlated with gill cover erection and dorsal fin spread. In the second experiment, a fight between two opponents was simulated and the oxygen consumption of the expected winner and loser was compared. Metabolic rates were not different between winners and losers before and during the fight, but winners showed higher oxygen consumption in the night after the fight. These results are in accordance with costs of display performance and with long‐lasting physiological consequences of winning or losing a fight. Aggr. Behav. 32:1–7, 2006. © 2006 Wiley‐Liss, Inc.     

Women with diarrhoea-predominant irritable bowel syndrome show an increased pressure response to 35% carbon dioxide stress challenge

The responses to inhalation of 35% carbon dioxide (CO(2)) as a stressor were compared in female irritable bowel syndrome (IBS) patients and healthy controls to assess potential differences in cardiovascular, neuroendocrine and behavioural responses to stress. A total of 22 women (12 patients with ROME II defined diarrhoea-predominant IBS and 10 aged-matched controls) were challenged with a single vital capacity breath of 35% CO(2) (with 65% oxygen). Beat-to-beat blood pressure and heart rate were recorded prior to, during and after the inhalation. Serum cortisol concentration and behavioural ratings were measured pre- and post-inhalation. A typical pattern of responses to CO(2) was observed, characterised by a reduction in heart rate and increases in serum cortisol and anxiogenic symptoms; however, these responses did not differ between groups. Both groups also demonstrated an increase in systolic blood pressure; however, this response was significantly enhanced in IBS patients compared to healthy controls (P < 0.05). These findings demonstrate that females with diarrhoea-predominant IBS have an exaggerated pressor response to 35% CO(2) stress challenge, suggesting a more stress-responsive sympathetic nervous system.     

Heart Rate Variability During Sympatho-excitatory Challenges: Comparison Between Spontaneous And Metronomic Breathing

Respiration influences heart rate variability, leading to the suggestion that respiration should be controlled to assess autonomic function by using heart rate variability. Clearly, control of respiration is advantageous or even essential in several experimental circumstances. However, control of respiration, by itself, produces a small, but significant, increase in mean heart rate and a decrease in respiratory synchronous variation in heart rate. We tested whether, in some experimental situations, it may be possible to arrive at similar interpretation about autonomic function with and without using control of respiratory rate. Heart rate spectral powers from nine subjects were compared between spontaneous and metronomic breathing during two sympatho-excitatory stresses, lower body negative pressure (LBNP) and head up tilt (HUT). The normalized spectral powers in supine and HUT during spontaneous breathing were: 0.43 and 0.75 in very low (VLF) and 0.28 and 0.09 in high frequency (HF) regions. The powers during metronomic breathing were: 0.36 and 0.82 (VLF) and 0.36 and 0.09 (HF). The powers in supine and LBNP during spontaneous breathing were: 0.43 and 0.81 (VLF) and 0.28 and 0.06 (HF). The powers during metronomic breathing were: 0.36 and 0.80 (VLF) and 0.36 and 0.07 (HF). All p values were <0.05. Therefore, changes in heart rate spectral powers during HUT and LBNP were similar during metronomic breathing and spontaneous breathing. These results suggest that in experimental designs such as in our study, using metronomic breathing may not provide any additional insight into autonomic function than that can be obtained during spontaneous breathing.     

Laterality of repetitive finger movement performance and clinical features of Parkinson’s disease

Impairments in acoustically cued repetitive finger movement often emerge at rates near to and above 2 Hz in persons with Parkinson’s Disease (PD) in which some patients move faster (hastening) and others move slower (bradykinetic). The clinical features impacting this differential performance of repetitive finger movement remain unknown. The purpose of this study was to compare repetitive finger movement performance between the more and less affected side, and the difference in clinical ratings among performance groups. Forty-one participants diagnosed with idiopathic PD completed an acoustically cued repetitive finger movement task while “on” medication. Eighteen participants moved faster, 10 moved slower, and 13 were able to maintain the appropriate rate at rates above 2 Hz. Clinical measures of laterality, disease severity, and the UPDRS were obtained. There were no significant differences between the more and less affected sides regardless of performance group. Comparison of disease severity, tremor, and rigidity among performance groups revealed no significant differences. Comparison of posture and postural instability scores revealed that the participants that demonstrated hastening had worse posture and postural instability scores. Consideration of movement rate during the clinical evaluation of repetitive finger movement may provide additional insight into varying disease features in persons with PD.     

The combined influence of body weight support and running direction on self-selected movement patterns

We investigated metabolic costs, muscle activity, and perceptual responses during forward and backward running at matched speeds at different body weight support (BWS) conditions. Participants ran forward and backward on a lower body positive pressure treadmill at 0%BWS, 20%BWS, and 50%BWS conditions. We measured oxygen uptake, carbon dioxide production, heart rate, muscle activity, and stride frequency. Additionally, we calculated metabolic cost of transport. Furthermore, we used rating of perceived exertion and feeling scale to investigate perceptual responses. Feeling scale during running was higher with increasing BWS (0–50%BWS), regardless of running direction (p < 0.05). Oxygen uptake, heart rate, and metabolic cost of transport were influenced by the interaction of running direction and BWS (p < 0.01). For example, metabolic cost of transport during backward running was greater than when running forward only when running at 0%BWS (i.e., 4.4 ± 1.1 and 5.8 ± 1.4 J/kg/m for forward and backward running, respectively: p < 0.001). However, rectus femoris muscle activity, stride frequency, and rating of perceived exertion during backward running were averages of 113.5%, 11.3%, and 2.8 rankings greater than when running forward, respectively, regardless of BWS (p < 0.001). We interpret our observations to indicate that environment (in the context of effective body weight) is a critical factor that determines self-selected movement patterns during forward and backward running.     

A “Healthy-Contingencies” Behavioral Intervention

Interventions based on functional analyses may result in better treatment outcomes than those using arbitrary reinforcers. However, functional analyses may be impractical in some situations, or an immediate intervention may be necessary while a functional analysis is being conducted. In these situations, delivering the social reinforcers most commonly identified by functional analyses (attention, access to tangibles, and escape from demands) following appropriate behavior and withholding these events following problem behavior may improve behavior. We assessed the extent to which this type of intervention would improve child behavior with three participants. All participants engaged in moderate to high rates of problem behavior and very little appropriate requesting during baseline, and high rates of appropriate requests and reduced rates of problem behavior during treatment.