Accommodation fatigue and dark focus: The effects of accommodation-free visual work as assessed by two psychophysical methods

Past studies of accommodation fatigue have yielded inconsistent results, partly because they have not used direct measures of accommodation, and partly because they may have been based on a misleading conception of the nature of accommodation. The dual-innervation theory of accommodation suggests that the resting position of accommodation may be neuromuscular rather than just muscular, and that it lies not at optical infinity, as assumed by older conceptions, but at some intermediate position (dark focus). Among the predictions that may be deduced from this theory is that long-term visual work not requiring active accommodation will not induce fatigue. The present study involved continuous measurements of dark focus for 10 young adults over a 3-h period, using the laser optometer with two psychophysical procedures Ibracketing and staircase. Consistent with the prediction, no changes in dark focus were found, in spite of the demanding visual task. Furthermore, it was found that both psychophysical methods yielded essentially identical results. The practical and theoretical implications of these results are discussed, and recommendations are given regarding situations in which each of the psychophysical methods is likely to be most useful.     

Duplex perception with musical stimuli

Duplex perception, a phenomenon previously demonstrated for speech stimuli, is demonstrated here for musical stimuli. In the first experiment, major and minor chords are produced by dichotic fusion of two simultaneous piano notes presented to one ear (perfect fifth) with a “natural” or “flat” single note presented to the opposite ear. Musically trained subjects perceive simultaneously both the single tone and a fused (major or minor) chord. The chords are labeled more consistently than the single notes, even though the fused chords differ solely in terms of the contralateral notes. In a second experiment, using pure tones in place of piano notes, other musically trained subjects individually exhibited categorical perception for either the fused chord or the single tones, but never for both types of stimuli. The duplex phenomenon is discussed in terms of its implications for its specific component modes of perception.     

Categorization reaction time,category structure,and category size in semantic memory using artificial categories

This study examined the effects of category structure and category size on categorization reaction time, artificial categories being used to obtain greater experimental control than is usually found in semantic memory research. Four artificial categories varying in structure (hierarchical and nonhierarchical) and size (8 or 16 instances) were introduced to 20 adolescent subjects over a 12-week period by means of stories, exercises, and discussions. Significantly longer categorization reaction times were required for instances from the hierarchical categories, but no set size effect was found. The application of clustering and multidimensional scaling procedures to subjects’ free recall data revealed that subjects had acquired the hierarchical structures but imposed their own structures on the other categories. These findings were interpreted within a spreading activation framework.     

Social networks,information-seeking,and the utilization of services

Voluntary participation by low-income and/ar high-risk populations in prevention-oriented human service programs is minimal and dropout rates are high. Examination of social networks as they relate to information-seeking and utilization behavior may provide a source of understanding. Two investigations are reported. The results of Study 1 indicate that high-risk referred women with denser networks attended fewer parent group sessions than did those whose networks were less dense and that the more contact a woman had with her kin, the fewer parent group sessions she attended. The results of Study 2 indicate that in a sample of low-income women participating in a supplementary food program, those women whose networks were characterized by lower density and less frequent kin contact were more likely to pursue professional child-rearing information and advice than women in denser, more kin-involved networks. In addition, a significant interaction between one's sense of competence as a parent and the structure of one's network was found to determine the overall frequency of information seeking.     

Variables influencing the learnability of individual signs and sign lexicons: A review of the literature

The last decade has seen an increase in investigations of the psycholinguistic and production attributes of sign and the features of sign which influence learning and memory. However, these investigations usually have not adequately delineated between the learning of individual signs as opposed to the learning of sign lexicons or sign strings and have not discussed features which might differentially influence the learning and recall of single signs and sign lexicons. The current paper reviews existing literature in the area of sign learning and identifies psycholinguistic, psychological, and production features which may influence learning and recall of individual signs as well as sign lexicons. Included in the discussion of features which are hypothesized to influence the learning of individual signs are sign translucency (rather than sign iconicity) and referential concreteness of the sign gloss. Varibles hypothesized to influence sign lexicon learning are cheremic similarity, acoustical confusion, and their relationship to proactive and retroactive interference. Implications of the effects of these variables on the learning of individual signs and on the learning of sign lexicons are discussed.     

Lesions of the basal ganglia, thalamus, and deep white matter: Differential effects on language functions

Forty-five patients with unilateral demarcated vascular lesions in the basal ganglia, the thalamus and the deep white matter were investigated with an "aphasia battery." Patients with basal ganglia lesions performed worse than both other groups in tests of articulation, syntax, and lexical functions. The deficit of patients with basal ganglia lesions on all expressive language modalities was lateralized to the left hemisphere. Patients with left thalamic lesions showed impairments of speech fluency and in the Token Test. Patients with white matter lesions alone showed no effect of laterality in tests of language functions. The results are discussed on the basis of a recent theory of the participation of the deep nuclei in language processing.     

Acquisition of probabilities in anticipatory appraisals of stress

Processes involved in predicting stressor events were examined from the perspective of ‘associative memory models’. Subjects were exposed to alphabetic letters which supposedly represented electrical resistors used in audio equipment, in the guise of marketing research. Each letter presentation was followed either by a burst of aversive white noise, signifying ‘resistor failure’ during a brief surge of current, or by a green light, signifying ‘resistor effectiveness’. After a programmed series of presentations, subjects were asked to make several judgments about each resistor; analyses of these judgments focused on the comparative influence exerted by the alternate stimulus events. Regardless of the type of judgment (e.g. probability of future noise, frequency of earlier silent outcomes, and so on), the determining stimulus property was the cumulative frequency of earlier aversive outcomes. Moreover, the dominance of this property was not altered by manipulations designed to elevate the salience of equally relevant benign outcomes. Results were discussed with reference to models of categorical memory and predictive confidence. Circumstances under which stress predictions may be especially inaccurate were considered, as were implications of the present findings for studies of differences in categorical-frequency memory processes associated with ‘depresed mood’.     

Working through a group's fantasy of the deceased leader's wish for the group's continuation

This paper reflects the working through of a group's fantasy that the deceased group leader wished the group to continue. As in any defense, the fantasy protected members from the pain of the finality of the leader's death. This article reveals the subjective experience concerning the effect of the leader's death on the group and members' intrapsychic struggle to separate and individuate from the deceased leader, while attending to and striving toward the group's continuation. The group's painful and growing individuation enabled the group to follow its own tasks without the spector of the deceased leader.