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.     

Ratio requirement and reinforcer effects in concurrent fixed-interval fixed-ratio schedules

The fixed-ratio requirement was varied in concurrent fixed-interval fixed-ratio schedules. Fixed-interval responding was reinforced by food. In different phases, fixed-ratio responding was reinforced by food or water. There was a direct relation between the ratio requirement and interval response rates when both responses were reinforced with food, but essentially no relation when the reinforcers were different. The role of reinforcers in concurrent schedules merits detailed study.     

An objective test of goodness of fit of the continuous strength model in STM

The continuous strength model of recognition memory was evaluated in a task where Ss were tested for recognition of 10-number lists using a rating procedure. Maximum likelihood estimates of the parameters of the model were obtained by an iterative method on a high-speed computer, and a chi-square goodness-of-fit test was performed for individual Ss. For 15 of 20 Ss, the chi-square values were nonsignificant, p < .05, indicating that the model provided a good fit to the data. Although the model gave a good fit to the data, the Δm measure of sensitivity was highly correlated with a true recognition score computed by subtracting false alarmsfrom correct recognitions.     

An investigation of the relationships between problem solving strategies, representation and memory

There has been considerable debate in recent years about the status of “imagery” in problem solving. The present experiment attempts to show that while subjects may employ representational strategies when they first encounter a class of problems, they abandon such strategies as they gain experience with the problems. It does this by asking subjects to answer unexpected questions which are based upon the information which they have just used to solve a problem. The hypothesis, which is supported by the results, is that increasing experience with problems will be paralleled by a decreasing ability to answer unexpected questions. The experiment also shows that such effects are not attributable to a build-up in proactive interference.     

The impact of event vividness,event severity,and prior paranormal belief on attributions towards a depicted remarkable coincidence experience: Two studies examining the misattribution hypothesis

Two studies examine the impact event vividness, event severity, and prior paranormal belief has on causal attributions for a depicted remarkable coincidence experience. In Study 1, respondents (n = 179) read a hypothetical vignette in which a fictional character accurately predicts a plane crash 1 day before it occurs. The crash was described in either vivid or pallid terms with the final outcome being either severe (fatal) or non‐severe (non‐fatal). Respondents completed 29 causal attribution items, one attribution confidence item, nine scenario perception items, a popular paranormal belief scale, and a standard demographics questionnaire. Principal axis factoring reduced the 29 attribution items to four attribution factors which were then subjected to a 2 (event vividness) × 2 (event severity) × 2 (paranormal belief) MANCOVA controlling for respondent gender. As expected, paranormal believers attributed the accurate crash prediction less to coincidence and more to both paranormal and transcendental knowing than did paranormal sceptics. Furthermore, paranormal (psychokinesis) believers deemed the prediction more reflective of paranormal knowing to both (1) a vivid/non‐fatal and (2) a pallid/fatal crash depiction. Vividness, severity, and paranormal belief types had no impact on attribution confidence. In Study 2, respondents (also n = 179) generated data that were a moderately good fit to the previous factor structure and replicated several differences across attributional pairings albeit for paranormal non‐believers only. Corresponding effects for event severity and paranormal belief were not replicated. Findings are discussed in terms of their support for the paranormal misattribution hypothesis and the impact of availability biases in the form of both vividness and severity effects. Methodological issues and future research ideas are also discussed.     

Social media addiction and psychological adjustment: religiosity and spirituality in the age of social media

Previous research indicates a significant association between social media use and psychological adjustment. The present study investigated whether religiosity/spirituality mediates the relationship between social media intrusion and psychological adjustment. Participants completed a demographic questionnaire, Religious Commitment Inventory-10, Spirituality Index of Well-Being, the DASS-21 Scales, and the Facebook Intrusion Questionnaire, which was altered slightly to include all types of social media. Results revealed that social media intrusion was significantly positively associated with depression, anxiety, and stress, and negatively correlated with spiritual well-being and the self-efficacy component of spiritual well-being. Furthermore, the self-efficacy dimension of spiritual well-being partially mediated the association between social media intrusion and psychological stress. From these results, it may be inferred that higher social media intrusion may have the ability to decrease specific aspects of spirituality, which may, in turn, negatively impact psychological adjustment. Limitations and future directions are discussed.