On optimal smoothing and derivative estimation from noisy displacement data in biomechanics

Estimating derivatives from noisy displacement data is a notoriously ill-posed problem in signal processing and biomechanics. Following the work of Wood and Jennings (1978) and Hatze (1979, 1981), the present paper describes the use of optimally regularized, natural quintic splines for estimating smoothed positions, velocities, and accelerations from equidistantly sampled, noisy position measurements. It appears that the nature of the boundary conditions of the data is of some importance, since various algorithms used hitherto result in artefacts throughout the data if the true derivatives at the record ends differ significantly from zero. Natural quintic splines do not suffer from this disadvantage below the third derivative.The ill-posed character of movement analysis has some interesting implications for movement synthesis and optimization, similar to the indeterminacy of muscular co-contraction from merely external, biomechanical measurements.     

Beyond the relational principle of reinforcement

Behavior under baseline conditions in which the contingency is absent can shed some light on the individual's performance under a schedule, but is insufficient as a basis for prediction of performance. This insufficiency of the baseline data runs counter to a recent formalization of the relational principle of reinforcement (Donahoe, 1977). A more satisfactory predictive model must incorporate not only the baseline level of the instrumental response and that of the contingent response, but also the schedule requirements, the character of each response in relation to the other, and the behavior required in simply switching from each to the other.     

Neuropsychological significance of phonetically accurate and phonetically inaccurate spelling errors in younger and older retarded spellers

The performances of two groups of retarded spellers (who were equated with respect to the level of deficient performance in spelling, but who differed in the level of phonetic accuracy of their misspellings) at two different age levels were compared to those of normal spellers who had been matched for age and WISC Performance IQ with the retarded spelling groups. The results indicated very marked differences in a number of linguistic skills between the normal spellers and the retarded spellers whose misspellings were characterized by phonetic inaccuracy. The performances of the retarded spellers who produced a preponderance of phonetically accurate misspellings differed markedly from those of the normal spellers only when the task demands involved fairly complex linguistic-cognitive operations. For the most part, the differences among the three groups were in evidence only at the older age level studied.     

The use of a self-control package to enhance temporal generality of a parent training program

The purpose of the present study was to examine the effectiveness of a self-control package in enhancing temporal generality of a parent training program. Sixteen mothers and their clinic-referred noncompliant children were assigned to either a parent training alone group, or a parent training plus self-control group. All mother-child dyads were treated individually by teaching the mother to reward compliance and other prosocial behavior, and to use time-out for noncompliance. In addition, mothers who also received self-control training learned to self-monitor their use of their new parenting skills and to reinforce themselves for use of the skill during a 2 month follow-up period. Assessment consisted of four home observations by independent observers prior to treatment, after treatment, and at a 2 month follow-up. The data indicated that the children in the parent training plus self-control group were significantly more compliant and less deviant at the 2 month follow-up than the children in the parent training alone group. Parental behavior did not differ between the two groups at the follow-up.     

Development of comprehension of sentences with “because” or “if”

The comprehension of sentences with “because” or “if” was investigated in children aged 2;9–11;11. Imitation, comprehension (choosing one of two picture sequences to go with a sentence), recognition (judging sentences with connective or structure differences as heard before or not), and synonymy (judging equivalence of meaning in sentences with different connectives or structures) tasks were administered, along with logical ordering, reversibility, and classification tasks. Above-chance responding in the comprehension task occurred by age 8, and in recognition and synonymy by age 10. Cognitive performance predicted 28.4% of the variance in the linguistic scores and cognitive success was concurrent with or preceded linguistic success. Comprehension of “because” and “if” appears to develop gradually, and is related to the development of certain operative rules.     

Studies in social influence: V. Minority influence and conversion behavior in a perceptual task

The effects of influence attempts by a majority and by a minority were examined on both a manifest response level and a latent perceptual level. Female subjects were exposed to a series of blue slides that were consistently labeled as green by a female confederate. The confederate was presented as a member of either a majority or a minority. On each trial, subjects were required to indicate the color of the slide presented and the color of the afterimage perceived on a white screen following removal of the slide. It was predicted that (a) the subject's judgment of the chromatic afterimage would be modified when the influence agent represented a minority, and (b) this modification will be more pronounced when the source of influence is absent than when it is present. The results supported the prediction in both the main study and its replication.     

An investigation of the arousal model of interpersonal intimacy

In a study designed to test Patterson's arousal model of nonverbal intimacy, the heartrate, gaze, smiles, body orientation, and body lean of each of 40 female subjects who interacted with an accomplice were measured. Within a factorial design, subjects were induced to view more or less favorably the accomplice, who subsequently increased or maintained the same level of nonverbal immediacy as she did in an earlier session. It was hypothesized that (1) an increase in the accomplice's immediacy would effect an increase in subjects' arousal (heartrate) which, in turn, (2) would lead to either reciprocal or compensatory nonverbal adjustments by subjects, depending on whether they viewed the accomplice more or less favorably, respectively. The results supported the first but not the second hypothesis. However, interpretation of the results suggests, nevertheless, that they may be consistent with the arousal model.     

Right hemisphere comprehension of verbs in patients with complete forebrain commissurotomy: Use of the dichotic method and manual performance

The paradigm of dichotic listening was used to investigate verbal comprehension in the right, so-called “nonverbal,” hemisphere. Verbal commands were presented to the right and left ears in the simultaneous (dichotic) paradigm. There were striking instances, especially when the left hemisphere was occupied with some extraneous task, in which the right hemisphere understood the verbal command and executed the appropriate motor responses. In those instances the left hemisphere gave no overt response. Although the left hemisphere was usually dominant, it can be nevertheless concluded that not only can the right hemisphere understand verbal commands but can also express itself manually by executing actions more complex than object retrieval or pointing. As has been known for some time, the blockage of the ipsilateral pathway seems so complete during dichotic listening in the commissurotomy patient that there is no report of the words in the left ear—only of those presented to the right. At the same time there is normal report when words are presented to the left ear alone. It was found in the present study, however, that this model is too simple and only applies to the verbal response paradigm of dichotic listening. Under circumstances of dichotic presentation where the stimulus in the left ear (ipsilateral pathway) is necessary or important to the left hemisphere for completing a task, words from both pathways are reported. One may conclude that there exists a gating mechanism in each hemisphere that controls the monitoring of each auditory pathway and the degree of ipsilateral suppression.     

Visual processing of multielement arrays and selective backward masking

In the first of two selective masking experiments, 7-letter rows were followed at several ISIs by a mask or no-mask and a bar-marker partial report cue. The results suggest that the arrays were processed ends-first and then, in general, from both ends towards the middle. In the second experiment, bar-marker partial report cues were presented at the onset or offset of 6-letter/1-digit or 7-letter rows. The subjects could not anticipate the category of the to-be-reported item with the alphanumeric displays. With a delayed cue, selective masking was obtained with both mixed category and pure letter arrays, but with simultaneous cuing, masking was always distributed across all serial positions. The results suggest that the subjects: (a) abstracted some information about category from the mixed arrays during an initial parallel stage of processing, (b) selectively attended to mainly the cued item with simultaneous probes with homeogeneous and mixed category displays, and (c) employed an ends-first processing strategy with both types of arrays when the bar-marker partial report cue was delayed.