ACQUISITION OF EXPRESSIVE SIGNING BY AUTISTIC CHILDREN: AN EVALUATION OF THE RELATIVE EFFECTS OF SIMULTANEOUS COMMUNICATION AND SIGN-ALONE TRAINING

Two methods of training autistic children to use manual signs were compared. Two children, one mute and one capable of some verbal imitation, were taught to use signs as expressive labels for pictures of objects. Using an alternating treatments design, speed of sign acquisition was compared across two training conditions in which signs were presented either accompanied by, or without, the corresponding verbal label. In both conditions, the training procedure incorporated reinforcement, modeling, prompting, fading, and stimulus rotation. The efficacy of training in both treatment conditions was demonstrated by the use of a multiple baseline control across signs, but no clear differences in acquisition speed across conditions were apparent. Posttests conducted to assess stimulus control of signing, and learning of verbal labels when these were present in training, showed that the behavior of the imitative, but not the mute, child was controlled by the verbal stimuli. The implications of the results both for understanding deficits characteristic of autistic children and for developing appropriate language training procedures are discussed.     

Reflections on likeness of meaning

Philosophical Studies -     

Determinants of information-seeking behavior

Two studies examined situational determinants of choice among anagram tests that varied both in difficulty and in diagnosticity (the information they provided about one's own ability). In both studies, subjects worked on a preliminary anagram test before making their choices. Study 1 manipulated level of performance on the preliminary test. Results showed that high performance led to preferring more difficult and more diagnostic tests. In Study 2, subjects were either paid or not paid for their performance on the preliminary test. Results showed that pay led to a preference for more diagnostic tests. Unexpectedly, results of both studies showed that although difficulty and diagnosticity were defined independently of one another, they were not perceived as such. Thus, high diagnostic tests were perceived as more difficult; more difficult tests were perceived as more diagnostic; and the difference between high and low diagnostic tests in perceived diagnosticity and choice of items (high diagnostic tests had higher scores on both measures) were more pronounced among more difficult tests. Motivational as well as cognitive interpretations of the results were discussed.     

Plasma membrane ordering agent pluronic F-68 (PF-68) reduces neurotransmitter uptake and release and produces learning and memory deficits in rats

A substantial body of evidence indicates that aged-related changes in the fluidity and lipid composition of the plasma membrane contribute to cellular dysfunction in humans and other mammalian species. In the CNS, reductions in neuronal plasma membrane order (PMO) (i.e., increased plasma membrane fluidity) have been attributed to age as well as the presence of the β-amyloid peptide-25-35, known to play an important role in the neuropathology of Alzheimer's disease (AD). These PMO increases may influence neurotransmitter synthesis, receptor binding, and second messenger systems as well as signal transduction pathways. The effects of neuronal PMO on learning and memory processes have not been adequately investigated, however. Based on the hypothesis that an increase in PMO may alter a number of aspects of synaptic transmission, we investigated several neurochemical and behavioral effects of the membrane ordering agent, PF-68. In cell culture, PF-68 (nmoles/mg SDS extractable protein) reduced [³H]norepinephrine (NE) uptake into differentiated PC-12 cells as well as reduced nicotine stimulated [³H]NE release. The compound (800–2400 μg/kg, i.p., resulting in nmoles/mg SDS extractable protein in the brain) decreased step-through latencies and increased the frequencies of crossing into the unsafe side of the chamber in inhibitory avoidance training. In the Morris water maze, PF-68 increased the latencies and swim distances required to locate a hidden platform and reduced the time spent and distance swam in the previous target quadrant during transfer (probe) trials. PF-68 did not impair performance of a well-learned working memory task, the rat delayed stimulus discrimination task (DSDT), however. Studies with ¹⁴C-labeled PF-68 indicated that significant (pmoles/mg wet tissue) levels of the compound entered the brain from peripheral (i.p.) injection. No PF-68 related changes were observed in swim speeds or in visual acuity tests in water maze experiments, rotorod performance, or in tests of general locomotor activity. Furthermore, latencies to select a lever in the DSDT were not affected. These results suggest that PF-68 induced deficits in learning and memory without confounding peripheral motor, sensory, or motivational effects at the tested doses. Furthermore, none of the doses induced a conditioned taste aversion to a novel 0.1% saccharin solution indicating a lack of nausea or gastrointestinal malaise induced by the compound. The data indicate that increases in neuronal plasma membrane order may have significant effects on neurotransmitter function as well as learning and memory processes. Furthermore, compounds such as PF-68 may also offer novel tools for studying the role of neuronal PMO in mnemonic processes and changes in PMO resulting from age-related disorders such as AD.     

KNOWING WHEN TO SAY WHEN: A SIMPLE ASSESSMENT OF ALCOHOL IMPAIRMENT

The use of writing samples as indices of alcohol impairment was explored. Students at a campus fraternity party wrote a sentence and their signatures before and after consuming alcohol (in beer and mixed drinks). Later, undergraduate and graduate students attempted to discriminate between pre- and postparty handwriting samples. The average percentage of correct discriminations of entrance and exit writing samples was 83.7% for sentences and 67.5% for signatures, and the percentage of correct discriminations increased directly with the blood alcohol concentration of the partier who gave the writing sample. When a partier's blood alcohol concentration reached 0.15, all of the judges accurately discriminated 90% or more of the sentences, and 25 of the 28 judges correctly discriminated at least 80% of the signatures. All of the judges correctly discriminated at least 90% of the 18 sentences written by partiers with a blood alcohol concentration of 0.12 or more. Implications of these findings for reducing the risk of driving while intoxicated are discussed, as well as directions for follow-up research.