Monitoring animals’ movements using digitized video images

An animal’s movements can be monitored continuously using video digitization techniques. We outline the differences between video frame-grabbers and column-scan digitizers, and describe two applications using column-scanners: detecting episodes of spontaneous locomotion and tracking the position of a moving appendage. Strategies are discussed for increasing the speed of software and for compressing the information in the video images into an analog motion signal to be displayed and stored for later analysis. Finally, the advantages and limitations of frame-grabbers and column-scan digitizers are assessed.     

A comparative analysis of two community stressors' long-term mental health effects

The investigation directly compared the long-term mental health consequences of two community-wide stressors, the Three Mile Island (TMI) nuclear accident and widespread unemployment due to layoff, in demographically comparable samples of women. Results showed a marked degree of similarity in the stressors' effects: Levels of subclinical symptomatology were elevated to similar degrees in each sample during the year following stressor onset, and symptom levels remained elevated in each sample 2 to 3 1/2 years later. Moreover, variables identified as predictors of enduring psychological distress were virtually identical for the two samples. Additional analyses revealed that the mental health status of unemployed husbands mediated the negative psychological effects of layoff on their wives. Implications of these results for understanding the long-term consequences of exposure to community-wide stress are discussed.     

Altering retrieval demands reverses the picture superiority effect

In Experiment 1 subjects studied a mixed list of pictures and words and then received either a free recall test or a word fragment completion test (e.g.,_yr_mi_forpyramid) on which some fragments corresponded to previously studied items. Free recall of pictures was better than that of words. However, words produced greater priming than did pictures on the fragment completion test, although a small amount of picture priming did occur. Experiments 2 and 3 showed that the picture priming was not due to implicit naming of the pictures during study. In Experiment 4 subjects studied words and pictures and received either the word fragment completion test or a picture fragment identification test in which they had to name degraded pictures. Greater priming was obtained with words in word fragment completion, but greater priming was obtained with pictures on the picture identification test. We conclude that (1) the type of retrieval query determines whether pictures or words will exhibit superior retention, and (2)our results conform to the principle of transfer appropriate processing by which performance on transfer or retention tests benefits to the extent that the tests recapitulate operations used during learning.     

Is menopause depressing? An investigation of three perspectives

This study examines three perspectives in the literature about menopausal depression. According to one, the physiological changes of menopause result in increased psychological distress. Another approach proposes that menopause is most depressing for women who occupy traditional female gender roles. The third asserts that menopause is not especially depressing for most women. This study empirically examines three perspectives using data from two community surveys. These analyses suggest menopausal status may not be associated with depressive symptomatology, either directly or indirectly through traditional gender roles.This research was supported in part by PHS grant numbers 5T32MH13043, 5T32MH16373, and 5T32MH15774. I appreciate the helpful comments I received from Janet Berkeley, Bruce Link, and an anonymous reviewer on earlier versions of this paper. I also am grateful to Lenore Radloff and NIMH for providing the CMHA data and to Harold Dupuy and NCHS for the HANES data.     

Caffeine,impulsivity, and memory scanning: A comparison of two explanations for the Yerkes-Dodson Effect

Two explanations for the Yerkes-Dodson Effect (1908) were tested. Easterbrook (1959) proposed that arousal reduces the range of cue utilization. Thus, arousal should interfere with the capacity for simultaneous (dual) memory scans. In contrast, Humphreys and Revelle (1984) proposed that arousal facilitates sustained information transfer but interferes with short-term memory. Arousal should thus reduce the time needed to prepare to respond but increase the time needed to scan memory. Either caffeine or placebo was given to 78 subjects who differed in impulsivity. They completed three versions of a memory-scanning task: two single-task versions (physical and category matches) and one dual-task version (either type of match). As predicted by Humphreys and Revelle, relative to placebo, caffeine lowered the intercept (p<.01), suggesting facilitation of sustained information transfer, but increased the slope (p<.05), suggesting impairment of access to short-term memory, of the regression of reaction time on log-transformed memory-set size. That caffeine had a main effect on slopes and on intercepts but did not interact with type of task suggests that arousal does not necessarily disrupt dual-task performance.     

The properties of retrieval cues constrain the picture superiority effect

In three experiments, we examined why pictures are remembered better than words on explicit memory tests like recall and recognition, whereas words produce more priming than pictures on some implicit tests, such as word-fragment and word-stem completion (e.g., completing -l-ph-nt or ele----- as elephant). One possibility is that pictures are always more accessible than words if subjects are given explicit retrieval instructions. An alternative possibility is that the properties of the retrieval cues themselves constrain the retrieval processes engaged; word fragments might induce data-driven (perceptually based) retrieval, which favors words regardless of the retrieval instructions. Experiment 1 demonstrated that words were remembered better than pictures on both the word-fragment and word-stem completion tasks under both implicit and explicit retrieval conditions. In Experiment 2, pictures were recalled better than words with semantically related extralist cues. In Experiment 3, when semantic cues were combined with word fragments, pictures and words were recalled equally well under explicit retrieval conditions, but words were superior to pictures under implicit instructions. Thus, the inherently data-limited properties of fragmented words limit their use in accessing conceptual codes. Overall, the results indicate that retrieval operations are largely determined by properties of the retrieval cues under both implicit and explicit retrieval conditions.     

Human patellar reflex and conditioned reflex compared electromyographically

Inspite of continued work on the stretch reflex and “voluntary” movement study of the conditioned stretch reflex declined early in this century. The present experiments surveyed seven classical conditioning regimens for the human rectus femoris EMG seen after a blow to the patellar tendon. It was possible to (1) rule out conditioning to a knee touch that occured together with the tap, (2) establish weak conditioned stimulus, Sc, control for a tape recorder click and subsequent fist clench that preceded the tap by variable elapsed times, and (3) establish strong Sc control for a tone that sounded an invariant 0.27 sec before the tap. There were large differences, however, in Sc power across subjects, as measured by amplitude, latency, and frequency of conditioned EMG activity that occured prior to tap or when the tap was omitted. Purely reflexive responses, especially later EMG segments, also varied in amplitude and frequency, to support a conclusion that numerous controlling stimuli added or competed from trial to trial. Further disclosure of Sc contributions, including those from movement-generated stimulation, is warranted, especially for behaviors whose rhythmic timings, as in locomotion, might favor Pavlovian conditioning.     

Noise stress and circadian arousal in self-paced computation

Previous work(Frankenhaeuser & Lundberg, 1977) has shown that unpaced mental arithmetic is performed at slower rates in noise, despite unchanged catecholamine indices of arousal; only male subjects were used, tested early in the day. Since the times of testing entail arousal effects that interact with noise stress, and the sex of subject further modifies these interactions, a new experiment was designed to include these variables. Men and women were tested on the Norinder mental arithmetic task, in quiet or in noise, either in the morning, when arousal was low, or during the early evening, when temperature curves indicate that arousal should be high. Analysis of the number of problems attempted shows a significant drop for men in noise in the morning, but an interaction due to reversal of the noise effect in the evening; there is no main effect of noise when women's scores are included. The results are compatible with interpretations combining motivation and cognition, and they demonstrate the importance of the experimental variables in explaining noise stress effects.The authors are indebted to the late David A. Shipp for his assistance in running subjects.