An investigation of the ability to process inferences in language following right hemisphere brain damage

Twenty-two right hemisphere brain-damaged and 22 non-brain-damaged patients were given a multiple-choice recognition task which contained true statements, statements which were inferentially true but not actually heard before, and false statements. It was hypothesized that if right hemisphere brain damage disturbs the ability to comprehend inferences, these subjects, unlike their normal counterparts, would not falsely recognize true inferences as heard before. This hypothesis was not confirmed. However, the right hemisphere group was poorer than controls at rejecting false statements. This behavior was speculated to be a retrieval difficulty, which was exacerbated if the information contained spatial or semantically similar material.     

Shape constancy and polar perspective

The distortion of polar perspective depends on the depth of the tridimensional shape and on the observation distance. In four experiments using 54 undergraduates as subjects, we found that a compensation process which takes depth and observation distance into account corrects for such distortions. Compensation was demonstrated in experiments in which deceptive information on depth and on observation distance was provided. The result was distortions of the perceived shapes that would be expected if compensation were based on the deceptive information.     

Decision processes in visual discrimination of line orientation

The contribution of decision factors to the meridional variations in line orientation discrimination was determined for two-alternative forced-choice experimental designs. Using Johnson's (1980) formalization of decision processes in discrimination tasks, we identified three decision factors: the decision rule, memory variance, and criterial noise. In a first experiment, we showed the effect of experimental design on orientation discrimination to be similar at horizontal and oblique standard orientations, indicating that the meridional variations in orientation discrimination were not due to a decision rule anisotropy. In a second experiment, the effect of the interstimulus interval was also found to be similar at both standard orientations, suggesting that the memory variance is isotropic in the orientation domain. The results of two other experiments supported the hypothesis that the meridional variations in orientation discrimination are not due to a criterial noise anisotropy. These different results strongly suggested that the oblique effect in line orientation discrimination is due to sensorial factors rather than to decision factors. Therefore, they further support the hypothesis linking the anisotropy of the preferred orientation distribution of Area 17-S cells (a single physiologically defined class of cells in the primary visual cortex) and the meridional variations in line orientation discrimination.     

Perceptual organization of behavior: a hierarchical control model of coordinated action

The behavior of individual subjects is compared with a hierarchical control system model of behavioral organization. Subjects varied the position of two control handles simultaneously to keep the distance constant between two pairs of lines. Three variations on this basic experiment that illustrate some fundamental properties of coordinated action are shown: first, how independent actions, compensating for unpredictable and undetectable disturbances, can produce a single behavioral result; second, how the ability to produce a particular result is maintained when the connection between action and result is changed; and third, how two independent outputs can appear to be related as coordinative structures when one output disturbs a result being controlled by the other. The correlation between the behavior of subjects and model in all experiments is typically on the order of .99. A detailed examination of the operation of the model shows that actions are structured by perception, not by central commands or equations of constraint.     

Range effects in successive discrimination

In two sets of experiments we examined pigeons' discrimination performance with a visual flicker-rate continuum, using a conventional successive discrimination procedure. In the first experiment, responses during the intermediate stimulus value were never reinforced, while responses during stimuli on either end of the continuum were reinforced periodically. In the second experiment, responses during stimuli from one end of the continuum were never reinforced, while responses during stimuli from the other end of the continuum were reinforced periodically. Results from both experiments show that discrimination between unchanged positive and negative stimulus values is a function of the range over which the total stimulus set varies. These range effects are comparable to effects found in absolute judgment tasks in human and animal psychophysics. In addition, the range effects reported here are not due to channel capacity, but may depend instead on variability in judgment criteria.     

Fluctuations and phase symmetry in coordinated rhythmic movements

Pendular, clocking movements typify mammalian terrestrial locomotion. They can be investigated with a procedure in which people swing hand-held pendulums at the wrists, comfortably and rhythmically. Pendular, clocking behavior was examined for in-phase and out-of-phase coordinations. The periodic timing and powering of rhythmic movements in the comfort state follow from different laws (Kugler & Turvey, 1986). One law guides the assembling of the reference frame for "clocking." Another law guides the assembling of the muscular, escapement processes determining the cycle energy. Wing and Kristofferson's (1973) method for parsing periodic-timing variance into independent "clock" and "motor" sources was applied. Mean periodicity was unaffected by phase. "Clock" fluctuations, however, were larger out of phase than in phase. "Motor" fluctuations were indifferent to phase but reflected the departures of individual wrist-pendulum systems from their preferred periods. It appears that an intended phase relation is realized as a constraint on "clock" states. These states are more stable under the in-phase constraint than under the out-of-phase constraint.     

Family therapy in a community mother and toddler project

A home centred family therapy approach is described based on the McMaster model. This approach was applied in a controlled trial of three forms of intervention for mother and toddler problems. In this paper the experience of applying the approach is reported.     

Preserved spatial memory in old rats survives 10 months without training

Aged rats with extensive prior training on the radial maze retain the capacity for accurate spatial working memory (WM) for at least 3 months without practice. To investigate the temporal limits of this influence of prior experience we compared the reacquisition of spatial WM by a group of experienced 21.5-month-old rats to the original acquisition by naive 3-month-old rats. The aged rats had received 225 radial maze tests between 3 and 11 months of age. Despite 10 months without practice the old rats rapidly reacquired critical performance. Their reacquisition was markedly superior to original learning by the young rats, even when delays as long as 5 h were imposed between the rats' fourth and fifth choices during the daily tests in the eight-arm maze. Additional tests showed that neither young nor old rats employed a response strategy to maintain accurate spatial WM performance. Experience clearly confers long-lived protection against the otherwise deleterious effects of aging on spatial WM, but the mechanism by which this influence arises is unknown.     

Scopolamine effects on memory retention in mice: a model of dementia?

Scopolamine-treated normal young human subjects exhibit memory dysfunctions analogous to those observed in demented patients. The dysfunctions are reversible by physostigmine but not by d-amphetamine which suggests that the memory impairment is specifically related to reduced cholinergic transmission caused by scopolamine. Scopolamine-induced amnesia has been proposed as a model for dementia where reduced cholinergic function is the suspected cause. We report seven experiments in young adult mice which examine scopolamine's effects on memory retention and whether its amnestic effects are specifically blocked by cholinergic agonists or cholinomimetics. Young adult mice were trained to avoid footshock in a T maze and their retention tested 1 week after training. Pretraining subcutaneous injection of scopolamine improved retention scores of "undertrained" mice at a dose of 0.01 mg/kg but impaired at a dose of 0.1 mg/kg. Post-training injection showed no effect at 0.01 mg/kg, enhanced retention scores at 0.1 mg/kg, and impaired at 1.0 mg/kg. The impairment by 1.0 mg/kg was blocked by injection 45 min post-training of each of two cholinergic drugs but was also counteracted by six drugs which act upon five other neural systems (catecholamine, serotonin, glycine, GABA, and hormonal). When scopolamine was injected 40 min pretraining, and each of eight drugs was injected immediately after training, the amnestic effect of scopolamine was only partially counteracted. This suggests that scopolamine impaired acquisition, in addition to some impairment of memory processing. This was confirmed by a direct study of acquisition rates of the avoidance response; 0.1 mg/kg of scopolamine impaired acquisition. The overall results indicate that pretraining administration of scopolamine impairs learning and to some degree memory processing. Counteracting scopolamine-induced amnesia, by either pretraining or post-training drug administration, is not specific to the cholinergic system.     

Some Interpersonal Effects of Imposing Guilt Versus Eliciting Altruism

Two groups of participants observed a videotaped interpersonal conflict involving two friends. The two groups were distinguished by their observing the videotaped protagonist making a request by imposing guilt or eliciting altruism. Immediately after observing the conflict, ratings were obtained from the two groups on their evaluation of the protagonist and their probable response to the protagonist's request. The major results indicated that when altruism was elicited instead of guilt imposed, participants indicated that the protagonist was more likable and respected and that they would be more likely to comply with the protagonist's request and less likely to become overtly or covertly angry at the protagonist.