Hindsight bias: An interaction of automatic and motivational factors?

If subjects are asked to recollect a former response after having been informed about the correct response, their recollection tends to approach the correct response. This effect has been termedhindsight bias. We studied hindsight bias in an experiment requiring numerical responses to almanac-type questions for physical quantities. We varied (1) the time at which the correct information was provided, (2) the encoding of the original responses by asking/not asking subjects to give a reason for the respective response, and (3) the motivation to recall correctly. We found that hindsight is less biased if reasons are given and if the correct information is provided at an earlier time. Motivation had only interactive effects: (1) With high motivation to recall correctly, the time the correct information was provided had no influence. (2) With reasons given, the variation of motivation showed no effect. These results rule out purely motivational and purely automatic explanations.     

Frontal amnesia and the dysexecutive syndrome

This study analyzes the memory deficits shown by an amnesic patient with bilateral frontal damage and a dysexecutive syndrome. He resembles a classic amnesic patient in showing grossly impaired episodic memory for both verbal and nonverbal material, together with normal digit span, and on occasion normal recency in free recall. He differs from the classic amnesic pattern however in showing an impairment in both the speed and accuracy of performance on tests of semantic memory, and in clear evidence for impaired performance on some though not all procedural learning tasks. Finally, his autobiographical memory was poor and subject to substantial confabulation. It is suggested that the pattern of deficits is consistent with a combination of a classic amnesic syndrome with the additional problems associated with the frontal dysexecutive syndrome, rather than exhibiting a qualitatively different form of amnesia.     

The perception of an optical flow projected on the ground surface

In most experiments in which the importance of visual control on postural stability is studied, optical stimuli attached to vertical surfaces are used. Analyses of long-term standing readjustments generally involve back-and-forth movements of a visual scene or its projection on vertical circular screens. In a natural environment, however, visual information is largely available from the ground. The aim of the experiment reported was to assess the effect of a flow pattern simulating an open outdoor setting on motion perception and postural control. Subjects were presented with an optical texture projected onto the ground. Periods of motionless texture alternated with equivalent durations of unidirectional flows. The change of position of the subject's centre of gravity over time was recorded on a force platform. Results show that the direction of body sway corresponded with that of texture motion. Important aftereffects, as shown in linear vection experiments, were also observed. However, the latency of postural responses was much shorter than with prolonged unidirectional flows produced in other locations of the visual environment. The hypothesis of an ecological specificity of the flows perceived on the ground during terrestrial displacements is discussed.     

Frontal cortex grafts have opposite effects at different postoperative recovery times

We studied the effect of different postoperative times on the behavioral recovery following brain implants. Adult male rats received cortical tissue grafts 2 weeks after aspiration of the medial frontal cortex. Either 2 (Immediate Group) or 28 (Delay Group) days after grafting, the performance of these rats on a behavioral battery, comprising the Morris water maze task, forepaw use, and grooming, was compared to that of rats with similar lesions and postoperative recovery times but no grafts. Rats tested immediately after receiving implants performed better on the spatial navigation task than rats with similar lesions but no grafts. This improvement, however, was less than that shown by rats with lesions but no grafts permitted to recover for 28 days before testing. In contrast, in the Delay Group, rats with grafts were more greatly impaired than were their operated controls. Neither lesions nor grafts affected grooming although the Immediate Group with grafts were significantly more impaired in using their forepaws during feeding than were any of the other groups. These results lead us to conclude that differing postoperative recovery times and task requirements may account for some of the inconsistent results of the influence of brain grafts on behavioral recovery reported in the literature. We also conclude that cortical tissue implants can have two effects with different time courses and opposite net behavioral effects.     

Age-related changes in working and reference memory performance and locomotor activity in the Wistar rat

Wistar rats of three age groups were tested in an automated tunnel-maze system of variable geometry to investigate whether changes in spontaneous locomotor activity and in learning and memory develop differentially or in a correlated fashion as a function of age. Senescent (30 months) as well as mature-adult (17 months) rats showed an age-correlated decline of locomotor activity as compared to the mature-young (5 months) group. Both working-memory (measured as within-trial arm discrimination performance) and reference-memory (measured as avoidance of "blind alley" visits) were severely affected in the senescent group, whereas the middle-aged animals suffered only from a working-memory deficit. The findings provide evidence that locomotor deficits do not necessarily interfere in the assessment of age-related changes in cognitive performance. Furthermore the results support the hypothesis that working and reference memory have different underlying physiological correlates and that these neuronal systems are differentially affected by the aging process.     

Type A behavior and emotional responses to uncertainty: A test of the self-appraisal model

The self-appraisal model of Type A behavior holds that Type A's desire an accurate appraisal of abilities, and respond to uncertainty about abilities with exaggerated attempts to generate diagnostic information. The model also predicts that the major emotional response to uncertainty for Type A's is anxiety. In this study, Type A's and B's were induced to succeed or fail on a task where they were either very certain or very uncertain of their subsequent ability levels. Task failure produced greater depression, anger, and frustration for all subjects. Consistent with the self-appraisal model's prediction, uncertainty (regardless of success or failure) led to greater anxiety for Type A's than for Type B's. In fact, greater uncertainty produced lower anxiety for Type B's, indicating that Type A's and B's differ dramatically in their emotional responses to uncertainty about abilities.