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.     

Evidence for an equality heuristic in social decision making

Subjects read a story in which five business partners needed to allocate the profits and expenses of the partnership in a fair and reasonable manner. Each of the partners worked independently and produced different gross incomes between $140 and $285. The gross incomes were to be divided into expenses and profits. Subjects were asked to fill in fair allocations in an accounting ledger. Three factors were manipulated: the target of the allocation task (either the expenses or the profits), the causal attributions for the differences in gross incomes (internal, external, or both), and whether the subjects were asked to fill in both columns (expenses and profits) or just one.

The results supported the hypothesis that the subjects heuristically used equality to make their allocations. Over 70% of the subjects allocated at least one column equally (although the frequency of equality use varied as a function of both the target of the allocation and the attribution given). Subjects allocated the target columns equally more often than non-target columns, even though equality for one column implied inequality for the other. The use of equality was also sensitive to the attribution given for the performance differences. Differences due to external factors, i.e., the number of people showing up at the market, produced the most equal allocations of profits (with unequal expenses) while the internal attribution produced the highest proportion of equal expense allocations (with unequal profits).     

Counseling with aliens

This paper addresses the issue of the semantic problem frequently found in cross denominational counseling in terms of the theological-psychological question of openness versus closure. It secondarily touches upon the issues of establishing and maintaining a level of trust in cross denominational counseling; suggestions of several tools for the counselor to use in such counseling situations; and the advantages of counselor tensions within the confines of a cross denomination counseling situation.     

Additional evidence for veridicality of perceptions based on physiognomic cues.

This study was designed to determine whether veridical interpersonal perceptions can be found on the basis of physiognomic cues. 21 male and female college students attempted to identify the correct social category [honor student, active or inactive in extracurricular events, and beauty queen (for female stimulus persons) or athlete (for male stimulus persons)] of 44 photographed male and female stimulus persons. Results demonstrated considerable veridicality, especially by male judges and of stimulus persons occupying categories which imply physical attributes.     

Comments on Richard Jeffrey

In this commentary, after first summarizing the three major theses of Jeffrey's paper ‘Probability and Falsification: Critique of the Popper Program’, and sketching out what I take to be his central argument, I criticize Jeffrey on two grounds. The first is that he has failed to explain why his version of Bayesianism provides us with better theories upon which to make decisions; the second is that he has offered a theory about decision-making that by-passes the important question: How can we make more rational decisions?     

A proposal for handling missing data

A method for dealing with the problem of missing observations in multivariate data is developed and evaluated. The method uses a transformation of the principal components of the data to estimate missing entries. The properties of this method and four alternative methods are investigated by means of a Monte Carlo study of 42 computer-generated data matrices. The methods are compared with respect to their ability to predict correlation matrices as well as missing entries. The results indicate that whenever there exists modest intercorrelations among the variables (i.e., average off diagonal correlation above .2) the proposed method is at least as good as the best alternative (a regression method) while being considerably faster and simpler computationally. Models for determining the best alternative based upon easily calculated characteristics of the matrix are given. The generality of these models is demonstrated using the previously published results of Timm.     

A simple device for the preparation of exactly aligned dichotic tapes

A system is described involving three tape recorders and a control device whereby dichotic tapes can be prepared with onset alignment accurate to a few milliseconds, or to a measured asynchrony if required. No modifications of any sort are necessary for the three tape recorders. The two channels are separately recorded in the speaker’s own time, the only requirement being that the separate words be spoken with an interword interval of 350 msec or more, to provide sufficient time for starting and stopping the system. A tone burst is placed directly on tape on another channel ahead of each word, the latter being delayed by recording in tandem through two tape recorders. The first recorder is set to the delay (echo, NAB) facility, while the tone is recorded directly on the second. Subsequently, when this is done for each item on the two speech channels, the device, described below. utilizes the tone bursts to align the two input recorders. It then rerecords each pair of words on to the third (output or dichotic) machine, to the desired synchrony/asynchrony, and interitem interval. The system can be left to align the two channels automatically. A maximum repetition rate of two dichotic pairs every 1.3 sec can be achieved with Revox A77 tape recorders.     

On-line brain stimulation: Measurement of threshold of reinforcement

This program and interface for a small computer (PDP8/e) performs the following operations: generates and delivers constant current stimulation to the brain of an animal, monitors electrical resistance at the stimulating electrode, and calculates the threshold of reinforcement based upon the frequency of characteristic pauses in the animal’s responding.     

Visual search under conditions of very rapid sequential Input rates

The purposes of the present experiment were to provide information on rate of information processing in visual perception and to determine the degree to which the “sequential blanking” effect found by Mayzner. Tresselt, and Cohen (1966) constituted a limitation on rapid sequential input rates. A 10-channel tachisto scope was employed that permitted controlled durations of each of the 10 channels and the 9 inter channel intervals. The S’s task was one of visual search or detection in which he searched for a target letter among noise letters. A temporal interval forced-choice procedure was used. In addition to varying the rate at which letters were sequentially presented, various irregular temporal spatial orders of presentation of the letter sequences were employed and the direction and orientation of the display in the visual field was varied as was also the spacing between adjacent stimuli. No evidence of “sequential blanking” was found either in terms of the detection criterion or in the Ss’ phenomenal reports. Detection performance was as good at a rate of 2 1/2 msec per letter as it was at a rate of 30 msec per letter.