Interval timing with gaps: gap ambiguity as an alternative to temporal decay

C. V. Buhusi, D. Perera, and W. H. Meck (2005) proposed a hypothesis of timing in rats to account for the results of experiments that have used the peak procedure with gaps. According to this hypothesis, the introduction of a gap causes the animal's memory for the pregap interval to passively decay (subjectively shorten) in direct proportion to the duration and salience of the gap. Thus, animals should pause with short, nonsalient gaps but should reset their clock with longer, salient gaps. The present authors suggest that the ambiguity of the gap (i.e., the similarity between the gap and the intertrial interval in both appearance and relative duration) causes the animal to actively reset the clock and prevents adequate assessments of the fate of timed intervals prior to the gap. Furthermore, when the intertrial interval is discriminable from the gap, the evidence suggests that timed intervals prior to the gap are not lost but are retained in memory.     

Sample and population score matrices and sample correlation matrices from an arbitrary population correlation matrix

A method for generating sample and population score matrices and sample correlation matrices from a given population correlation matrix is developed. An example giving the desired matrices for a population Guttman simplex correlation matrix is presented.The computations for this paper were done on Illiac, an electronic computer of the Digital Computer Laboratory of the University of Illinois. Mr. S. Hunka assisted in these computations. The final version of this paper was prepared while the senior author was a U. S. Public Health Service Fellow at the Center for Advanced Study in the Behavioral Sciences.     

Abacs for determination of a correlation coefficient corrected for restriction of range

Abacs approximating the product-moment correlation for both explicit and implicit selection are presented. These abacs give accuracy to within .01 of the corresponding analytic estimate.     

A note on the Tryon-Kaiser solution for the communalities

The Tryon-Kaiser solution for the communalities is reviewed. Numerical investigation suggests that the procedure is applicable if and only if the correlation matrix has unique minimum rank communalities. This implies that this approach to the communality problem is not general enough to be of practical use.     

Timing in pigeons: The choose-short effect may result from pigeons’ “confusion” between delay and intertrial intervals

In conditional discriminations, when samples differ only in duration, pigeons typically show a choose-short effect (i.e., higher matching accuracy on short-duration-sample than on long-durationsample trials with increasing delay between sample and comparison stimuli). That this effect depends on the similarity of retention interval (RI) and intertrial interval (ITI) houselight illumination conditions has been taken as evidence that pigeons judge duration relative to a temporal background. In the present experiment, pigeons trained with duration samples and with the ITI either illuminated or not showed a choose-short bias only when the RI illumination on test trials was the same as the ITI illumination had been in training. The results support the hypothesis that the choose-short effect results from the pigeons’ confusion between the ITI and the RI.     

Alpha factor analysis

A distinction is made between statistical inference and psychometric inference in factor analysis. After reviewing Rao's canonical factor analysis (CFA), a fundamental statistical method of factoring, a new method of factor analysis based upon the psychometric concept of generalizability is described. This new procedure (alpha factor analysis, AFA) determines factors which have maximum generalizability in the Kuder-Richardson, or alpha, sense. The two methods, CFA and AFA, each have the important property of giving the same factors regardless of the units of measurement of the observable variables. In determining factors, the principal distinction between the two methods is that CFA operates in the metric of the unique parts of the observable variables while AFA operates in the metric of the common (communality) parts.On the other hand, the two methods are substantially different as to how they establish the number of factors. CFA answers this crucial question with a statistical test of significance while AFA retains only those alpha factors with positive generalizability. This difference is discussed at some length. A brief outline of a computer program for AFA is described and an example of the application of AFA is given.The first version of this paper was prepared while the senior author was a U. S. Public Health Service Fellow at the Center for Advanced Study in the Behavioral Sciences and while the junior author was Director of Research of the Palo Alto Public Schools.     

Exposure in vivo vs social skills training for social phobia: long-term outcome and differential effects

This study examined the long-term effectiveness of specific exposure in vivo (individual IE or group GE) and of office-based social skills training (group SST) in two groups of patients with social inhibition (primary social skills deficits or primary social phobia). Seventy-eight outpatients were divided into these two subgroups according to clinical assessment. Twenty-seven patients received SST which consisted of 25 twice a week 90-min group sessions: 32 patients received GE and 17 IE. Exposure in vivo consisted of 4 weekly (8-hr in the group condition included 2 hr discussion; 3 hr in the individual condition included 1 hr discussion) sessions. Self-rating-assessments were carried out at pre- and post-treatment, at 3 months- and 2.5 yr follow-up. The general results indicate that all three treatment modes led to clinically and statistically-significant improvements in the main problem area (social anxiety, skills deficits), in other neurotic complaints (depression, obsessions, psychosomatic complaints) and in attribution-style. Patients with the diagnosis of primary phobia seemed to get the same profit from either treatment and showed slightly better gains (in all treatment modalities) than patients with skills deficits at long-term follow-up. Within the subgroup with skills deficits there was a tendency for superior outcome of group exposure. These results and recommendations for future research are discussed.     

Angular velocity discrimination

Three experiments were designed to investigate naive observers' abilities at discriminating the rotational velocities of two simultaneously viewed objects. In Experiment 1, rotations could occur about parallel or orthogonal axes, with initial orientations in phase or out of phase, and (for parallel rotational axes) in the same or opposite direction. Differential thresholds were approximately 10%. In Experiment 2, stimulus objects differed in the number of faces revealed in rotation (three vs. four). Observers' response curves had no greater spread, but their PSEs (points of subjective equality) were shifted such that there was a partial compensation for faces revealed per unit time. In both Experiment 1 and Experiment 2, performance was consistent across rotational axis and directional conditions. In Experiment 3, the effect of object size was examined, in order to determine the extent to which angular velocity judgments are influenced by the tangential velocity of the faces. When the comparison cube's edges were half the length of the standard's, PSEs were elevated 18.5%. Taken together, these data suggest that observers are able to discriminate angular velocities with a competence near that for linear velocities. However, perceived angular rate is influenced by structural aspects of the stimuli.     

Visual acceleration detection: effect of sign and motion orientation

Thresholds for the detection of constant acceleration and deceleration of a discrete object moving along horizontal and vertical axes were studied. A staircase methodology was used to determine thresholds for three average velocities (0.7, 1.2, and 1.7 deg/sec). Thresholds, expressed as the proportion of velocity change, did not differ significantly among the average velocities; thus, a consistent Weber-like fraction is suggested by the data. Furthermore, there was an interaction between the axis of motion (horizontal or vertical) and the sign of the velocity change (acceleration or deceleration): accelerations were easier to detect along the vertical axis, decelerations along the horizontal axis.     

Assessing the Flexibility of Managers: A comparison of methods1

Despite keen interest, questions remain about defining and measuring the behavioral flexibility of managers. This paper reports a conceptual and empirical comparison of three alternative methods of assessing this construct. Results suggest that the way managerial flexibility is typically assessed in practice – as a trait‐like characteristic with coworker ratings that describe a general tendency to vary behavior across situations – is deficient. However, more complex models that represent flexibility as a higher‐order construct reflecting mastery of specific and opposing behaviors in both the social/interpersonal domain and the functional/organizational domain show promise. They demonstrate construct validity evidence, predict as much as 42% of the variance in overall effectiveness, and provide more specific diagnostic information to guide behavior change.