Unawareness of visual and sensorimotor defects: A hypothesis

A theory is proposed to account for unawareness of blindness, hemianopsia, and hemiplegia, and for phantom limb after amputation. It is assumed that interruption of a sensory pathway at any level--from peripheral nerve to primary sensory cortex--is not associated with any immediate sensory experience that uniquely specifies the defect. Instead the sensory loss must be discovered by a process of self-observation and inference. Discovery is easy for defects that create major functional disability, such as total blindness. Hence unawareness of total blindness occurs only in association with severe intellectual impairment, precluding the required self-observation and inference. In contrast, hemianopsia is difficult to discover because several mechanisms automatically compensate the defect effectively. Thus unawareness of hemianopsia is common, even in intellectually normal individuals. Insensate fields are often the source of suggested (false) percepts, because no information from such a field specifies the absence of a sensory stimulus. The most powerful source of suggestion is sensory activity in uninvolved portions of the affected sensory field. Thus hemianopsics may perceive complete geometric forms when only incomplete forms are shown and the missing portion falls in the hemianopsic fields. Such perceptual completion also occurs in hemianesthetic hemiplegics, creating the illusion that there are normally functioning limbs on the affected side. This perceptual completion increases the difficulty of discovery of hemianesthetic hemiplegia, but the disability is still sufficiently obvious that some additional cognitive impairment is invariably present in patients with lasting unawareness of hemiplegia. Phantom limb after amputation is the product of perceptual completion without associated cognitive impairment. The patient with phantom limb is thus aware of the illusory quality of his phantom. Some insight into the neural basis of perceptual completion and of unawareness of sensory loss may derive from considering sensory systems and associative cortex as parallel-distributed processing mechanisms.     

Effects of incidental pictorial and verbal adjuncts on text learning

In this study, college students read and studied texts on historical figures in psychology, which were supplemented by drawings and/or brief biographies of these persons. In Experiment 1, a 2 x 2 between-groups design was conducted in which students received one adjunct with each text, both adjuncts, or neither. In Experiment 2, a single group of students received a within-subjects manipulation of the same adjunct conditions. In the between-groups comparison, students receiving biographies learned less of the target text passages, with the group receiving illustrations and biographies performing least accurately. In the within-subject conditions, texts accompanied by an illustration were better learned, with these students doing best on the text with both picture and biography. The results suggest that adjuncts may emphasize some texts, at the expense of learning from the other texts, but that too much adjunct material interferes with the learning of the target passages.     

Stress, appraisal, coping, and social support as predictors of adaptational outcome among dementia caregivers

A stress and coping model was used to study predictors of individual differences in caregiver adaptation. A total of 54 family caregivers of elderly dementia patients completed interviews and questionnaires assessing the severity of patient impairment and caregiving stressors; caregiver appraisals, coping responses, and social support and activity; and caregiver outcomes, including depression, life satisfaction, and self-rated health. Correlational and regression analyses supported the utility of the stress and coping model. Appraisal, coping responses, and social support and activity were significant predictors of caregiver outcome, even when severity of caregiving stressors was statistically controlled. The importance of a multidimensional approach to assessing caregiver outcomes was supported by regression analyses indicating that each caregiver outcome was predicted by different patterns of stressors, appraisal, coping, and social support and activity. Results are discussed in terms of a stress and coping model of caregiving, and clinical implications for work with caregiving families.     

Energy Processing Characteristics of Spatial Vision: The Spectral Characteristics of Perceptive Fields

To this stage a large amount of information has accumulated on one-dimensional broadband frequency channel characteristics of the visual system. Only recently have attempts been made to define additional two-dimensional narrow-band response profiles-particularly in central vision. In this paper questions concerning the number, tuning widths and phase sensitivity of such two-dimensional narrow-band coding units are reviewed. Results with grating and two-dimensional images are discussed, particularly within the context of energy processing and information reduction strategies which reflect human performance. Finally, a consequent principle of univariance is defined and shown to hold with such filter units.     

6-羟基多巴胺所致旋转行为的动物模型

选用神经毒素(6-OHDA)造成动物大脑黑质纹状体的单侧性损伤,致使动物的大脑两半球机能显示不对称性。致伤后以可卡因诱发动物的旋转行为。 本实验共观察了成年的Holtzman种系雌性大白鼠43只。结果表明,有38例(88.37％)的多巴胺的耗竭率在85一100％,它们的伤情较为理想。但是,3只动物(6.98％)的多巴胺的耗竭率小于60％,2只动物(4.65％)的多巴胺的耗竭率在60—84％。 本文详细地介绍了如何制备和利用旋转仪自动记录动物的旋转行为,以及用高效液相色谱法测定大脑纹状体内多巴胺的含量。     

Signal detection and localization by real observers

A model for detection and localization (DAL) was applied to the processing of a noise-masked tonal signal by human Ss. The model was supported in that consistent values of d’ were obtained from rating. forced-choice (FC). and DAL procedures. Also. the rating d’ accurately predicted per cent correct on the FC and DAL trials. A shortcoming of the theory was its failure to account satisfactorily for the details of FC and DAL stimulus-response matrices.     

The effects of stimulus familiarization on patterns of visual selection

Patterns of visual selection were recorded as Ss viewed pairs of stimulus drawings in which the two members were either both incongruous or both banal. Prior to presenting the paired stimuli, S was preexposed to either one member of the stimulus pair or to the incongruous or banal counterpart of one member of the stimulus pair. The results indicate that: (1) preexposure to a stimulus reduced its potential to elicit looking responses, and the magnitude of that reduction was greater for incongruous stimuli than for banal stimuli; (2) preexposure to an incongruous stimulus affected the potential of its banal counterpart to elicit looking responses, but preexposure to a banal stimulus did not affect the potential of its incongruous counterpart to elicit similar responses; and (3) the reduced potential of the preexposed member of a stimulus pair to elicit looking responses waned after 10 sec. These results were discussed in light of an “information-conflict resolution” model of visual selection.     

Elective mutism in a first grader: The remediation of a complex behavioral problem

Teachers frequently deal with unusual and perplexing behavioral problems in their classes. This study demonstrates how spontaneous and prompted speech were produced in a six-year-old mute by a first-grade teacher and her aide. A reinforcement system for peer-prompted speech and spontaneous speech was employed in three separate school classes in a multiple-baseline fashion. The reinforcement system produced prompted and spontaneous speech in each situation. Postchecks in the second grade indicated the child was still speaking and conversing spontaneously with his peers. This study suggests a method that teachers can use in the classroom to deal with this severely handicapping condition.