Selective effects of barbiturate and amphetamine on information processing and response execution

In a 3 × 2 × 2 factoral experiment, 12 subjects carried out a choice reaction task with reaction time (RT) and movement time (MT) as response measures.Independent variables were drug treatment (amphetamine, barbiturate, placebo), visual stimulus degradation and S-R compatibility. Visual stimulus degradation and S-R compatibility showed additive effect on the RT, but did not affect the MT. This confirms that stimulus encoding, response selection and response execution represent independent processing stages. The two drugs had selective effects on the RT and the MT. Barbiturate (as compared to placebo) had no effect on the MT, but it lengthened the RT, and this effect was additive with the effects of S-R compatibility but showed an interaction with the effects of stimulus degradation. Amphetamine (as compared to placebo) shortened the MT, but there was no significant main effect of amphetamine on the RT although the interaction with the effect of S— compatibility was significant. These results suggest that barbiturate affects stimulus encoding whereas amphetamine affects response-related processes..     

Tests that discriminate between dyslexic and other learning-disabled boys

Dyslexic and nondyslexic boys within a single community's learning-disabled class were given a set of tests; performance on each of these tests has been reported to be significantly impaired in other dyslexic children compared to learning-disabled and normal groups. Linear discriminant function analysis revealed that error types rather than levels of performance best separated the carefully matched learning-disabled groups. Slow naming and high percentage of “dysphasic” errors characterized dyslexic boys. Visual temporal-spatial matching and “configuration-deficient” perceptual errors characterized the adequate readers who have other learning disabilities.     

Functional cerebral lateralization in subtypes of disabled readers

This study investigated the functional cortical organization of reading-disabled boys and age-matched normal readers. Subjects were initially classified according to E. Boder's (1971a. In B. Bateman (Ed.), Learning disorders. Seattle: Special Child Publications. Vol. 4.) distinction between dysphonetic children (who make nonphonetic, bizarre spelling errors), dyseidetic children (who make phonetically acceptable errors, but do not respond to some words as “wholes”), and children who display normal error patterns (who make phonetically acceptable errors and respond to words as “wholes”). It was hypothesized that different types of reading disability would be associated with different patterns of lateralized brain function. This proposal was examined by testing subjects on three experimental neuropsychological measures—hemispheric time-sharing, conjugate lateral eye movements, and tactile directional perception. Conjugate lateral eye movements were disregarded as the control subjects failed to show predicted asymmetries on this measure. The two other measures were considered valid and demonstrated atypical lateralization in the reading-disabled groups. Lateralization of verbal and/or spatial functiosn differed among the reading-disabled groups and an attempt was made to relate these atypical patterns to the type of reading difficulties presented.     

Falsification of matching theory: changes in the asymptote of Herrnstein''s hyperbola as a function of water deprivation.

Five rats pressed levers on variable-interval schedules of water reinforcement at various levels of water deprivation. In one phase of the experiment, three deprivation conditions that replicated conditions in Heyman and Monaghan (1987) were arranged, along with three less extreme deprivation conditions. In a second phase, water deprivation was arranged so that subjects were exposed to a greater range of access to water per day. Herrnstein's hyperbola described the rats' response-rate data well. The y asymptote, k, of the hyperbola appeared roughly constant over the conditions that replicated those of Heyman and Monaghan, but decreased markedly when less extreme deprivation conditions were included. In addition, k varied systematically when the second method of arranging deprivation was used. These results falsify a strong form of matching theory and confirm predictions made by linear system theory.     

Risky decision: Attention effects or masking effects?

The Marshak bid procedure shows that more money is required to induce a S to exchange gamble a for gamble e and then e for b if e differs from a only in the winning amount and differs from b only in the probability of winning, rather than if e differs from a only in the probability of winning. This is contrary to most theories of risky decision making which imply that the amount of money necessary to effect a 2-step exchange between a and b should be independent of the intermediary gamble. One might attempt to explain the effect by saying that the S attends to the dimension which is different between gambles. But the explanation is untenable if one assumes that states of attention are defined as weightings of the dimensions. An alternative explanation is put forward which basically assumes that winning amounts mask differences in probability of winning more than vice versa. The formalization of the theory is given in terms of Fechnerian integration over imperfect differentials.     

Effects of positive and negative adult-child interactions on children's social preference

The effects of positive and negative interactions on children's performance and preferences for the adults associated with each type of interaction were studied. Five children served as subjects during daily sessions in which each of three adults followed prescribed patterns of social interaction. One adult (positive) dispensed positive comments contingent upon either color-sorting or completion of arithmetic problems; a second adult (negative) mildly reprimanded the child for off-task behavior; and the third adult (extinction or nonreactive) said nothing to the child when he was present. Following each session the three adults reentered and the child chose one of them for an additional period of interaction. Three response measures (frequency, latency, and percent of time on-task) and children's adult preferences were obtained daily. The negative adult affected the most task behavior and had strongest stimulus control; the positive adult, though exerting little control over children's behavior, was the most preferred. Children's adult preferences were not specific to the task setting, but were observed across a variety of contexts.     

Progressive elaboration and memory for order in children

Three experiments were conducted investigating memory for items and order in a progressive elaboration paired-associates task. For all subjects retention of item information was improved by the use of progressively elaborated interactions relative to a no-elaboration control condition. For second and fourth graders, retention of order information depended upon the type of elaboration. If successive interactions were added in a logical temporal order, retention (of order information) was superior to the case where the successive interactions were added in a random order. This effect was not obtained with kindergarten children. In the second and third experiments, kindergarteners were instructed regarding the sequencing of the successive items, and results similar to those obtained with older children ensued. The data were discussed in terms of Tulving's distinction between episodic and semantic memory.     

The role of contextual cues in mediating transfer

An experiment was conducted with sceond-grade children to test the hypothesis that contextual (task format) changes limit the transfer of learning. The Ss learned two problems employing different formats concurrently and were then given a single transfer problem similar in format to one of the training problems. The transfer data were predictable from a consideration of the similar format training problem and independent of the different format training problem. This indicated that contextual cues were stored during training and played a role in determining transfer.     

Auditory-verbal short-term memory impairment and conduction aphasia

The specific impairment of performance on repetition tasks has classically been identified with conduction aphasia. It is argued that this impairment can be subdivided and a deficit in span performance distinguished from that of the reproduction of single words. An explanation of the span deficit in terms of auditory-verbal short-term memory is preferred to hypotheses involving disconnections or damage to order retention systems. It is shown that a short-term memory component is present in many patients previously classified as conduction aphasics.     

Treatment of dental fears by imaginal flooding and rehearsal of coping behaviour

All combinations of high versus low arousal imaginal flooding, and coping versus no-coping imaginal rehearsal, were compared in the modification of dental fear. About one half of all subjects seen successfully completed dental treatment, although significant differences were found between groups in anxiety reduction before and during dental examination, which favoured the low arousal flooding groups. Coping rehearsal did not influence anxiety, but interacted with arousal level of flooding to determine subsequent dental attendance. The results suggest that flooding without coping rehearsal had little effect at high levels of arousal, but good results at low levels. Flooding with coping rehearsal on the other hand, had mixed results. At high arousal levels avoidance was reduced but not anxiety, while at low levels anxiety was reduced but not avoidance. The implications for further research on coping rehearsal are discussed.