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.     

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.     

The Behavioral Dyscontrol Scale and Functional Status Among Elderly Medical and Surgical Rehabilitation Patients

This research was conducted in a sample of 150 older adults (mean age = 78.0) who were inpatients receiving rehabilitation services for a variety of medical and postsurgical conditions. The purpose of the study was to test the hypothesis that the Behavioral Dyscontrol Scale (BDS), a measure of the ability to use intentions to guide purposeful activity, would be strongly associated with concurrent functional status after controlling for age, sex, education, severity of pain, medical comorbidity, depression (Geriatric Depression Scale), and general mental status (Mini Mental State Exam [MMSE]). Functional status was assessed by rehabilitaion nurses' ratings of patients on 11 individual Activities of Daily Living (ADL) items and the Barthel Index. The hypothesis, tested by means of multiple regression analysis, was supported by the results. The BDS was the independent variable most strongly associated with all 11 ADL items and the Barthel Index. The MMSE contributed significantly to none of the models. Other covariates made minimal contributions to the variance shared with functional ability. Consistent with prior results in other samples, the ability to use intentions to guide purposeful behavior appears to be an important contributor to everyday functioning among older adults.     

Goal programming with dynamic goals

The aim of this paper is to present a dynamic goal programming scheme. Throughout the revised literature, most of the dynamic goal programming approaches use target values on the final value of the objective functionals. In this paper, dynamic target values are assumed, so that they control not only the final values of the corresponding functionals, but their evolution along the planning period. As a result, the scalar problems are also dynamic ones, where the evolution of the deviation variables is minimized. A lexicographic dynamic goal programming algorithm is developed on these basis, and some considerations are made on the efficiency of the final solutions. © 1998 John Wiley & Sons, Ltd.     

Demonstrating the effect of context on order effects for an army air defense task using the patriot simulator

The results reported herein support the hypotheses that (1) situation-specific, contextual features of a task can cause people to use explanation-based reasoning (Pennington and Hastie, 1993); (2) such reasoning can cause experienced personnel, both individually and in two-person teams, to reinterpret the meaning of the same information when it is presented in two different ordered sequences; and (3) the result will be primacy or recency (or no) effects depending on whether the most recent conflicting information can be explained away or not, respectively. These results extend the belief-adjustment model proposed by Hogarth and Einhorn (1992), which does not address information reinterpretations, and always predicts recency effects for an evaluation task with a short series of conflicting information. More generally, the results demonstrate the importance of situation-specific, contextual features in understanding judgment processes. © 1997 John Wiley & Sons, Ltd.