Knowledge that Transforms

Memory span is smaller for (a) items taking longer to pronounce and (b) phonologically more similar items. We investigated the relation between the two effects. Chase (1977) found that phonologically similar items were pronounced more slowly than dissimilar ones in a pronunciation task. A pronunciation rate difference in immediate recall could explain the phonological similarity effect as a special case of the word-length effect. Instead, the study found that pronunciation rates were equal. In the equation s = rt, span equals pronunciation rate times trace duration, word-length affects r while phonological similarity affects t. The two effects are shown to be complementary.

The nictitating membranes of six rabbits were classically conditioned using a pontine-nucleus-stimulation conditioned stimulus with an air-puff unconditioned stimulus and a tone conditioned stimulus with an air-puff unconditioned stimulus. Multiple-unit neuronal activity in the cerebellar interpositus nucleus was monitored during the stimulation and tone training. Significant increases in the number of learned responses as well as increases in conditioning-related neuronal activity in the interpositus were observed during stimulation training. The number of conditioned nictitating-membrane responses and level of learning-related neuronal activity remained high during subsequent tone training. These data show that the cerebellum is activated in a similar manner when pontine stimulation or peripheral tones are used as a conditioned stimulus during classical nictitating-membrane conditioning.

The link between behavioral responsiveness to stress and subsequent health has been demonstrated in adults but not in infants and very young children. The ability of infants to suppress responding to acutely painful events was examined both as a function of neonatal status and as a predictor of incidence of illness at 18 to 24 months. Responding to stress in early infancy was predictive of later health but the nature of the relation depended on the maturity of the child.

Paired associates were presented to 25 surgical patients following the induction of anesthesia by thiopental, vecuronium, and isoflurane. Postoperative testing (immediately or after two weeks) showed no free recall for the list; nor was there significant cued recall or recognition, compared to a matched control list. However, a free-association task showed a significant priming effect on both immediate and delayed trials. At least under some conditions, adequate surgical anesthesia appears to abolish explicit, but not implicit, memory for intraoperative events.

Performance of college undergraduates on the Reading Comprehension task of the SAT was well above chance when the passages were deleted. Moreover, examinees and test items performed similarly with or without the passages: individual performance correlated with verbal SAT score, and the difficulty of items belonging to a passage correlated with a normative measure based on equated delta. The findings demonstrate that the Reading Comprehension task substantially measures factors unrelated to reading comprehension.

The research reported in this paper uses novel stimuli to study how speech perception is influenced by information presented to ear and eye. Auditory and visual sources of information (syllables) were synthesized and presented in isolation or in factorial combination. A five-step continuum between the syllables ibal and idal was synthesized along both auditory and visual dimensions, by varying properties of the syllable at its onset. The onsets of the second and third formants were manipulated in the audible speech. For the visible speech, the shape of the lips and the jaw position at the onset of the syllable were manipulated. Subjects’ identification judgments of the test syllables presented on videotape were influenced by both auditory and visual information. The results were used to test between a fuzzy logical model of speech perception (FLMP) and a categorical model of perception (CMP). These tests indicate that evaluation and integration of the two sources of information makes available continuous as opposed to just categorical information. In addition, the integration of the two sources appears to be nonadditive in that the least ambiguous source has the largest impact on the judgment. The two sources of information appear to be evaluated, integrated, and identified as described by the FLMP-an optimal algorithm for combining information from multiple sources. The research provides a theoretical framework for understanding the improvement in speech perception by hearing-impaired listeners when auditory speech is supplemented with other sources of information.

The standard economic assumption about human behavior is that it optimizes overall utility. But in many controlled experiments on behavioral allocation, it has been found that organisms allocate their behavior so as to earn equal average rates of reinforcement from all alternatives. Equalizing average rates of reinforcement is a principle of allocation that generically violates the assumption of optimality.

Given the task of diagnosing the source of a patient's allergic reaction, college students judged the causal efficacy of common (X) and distinctive (A and B) elements of compound stimuli: AX and BX. As the differential correlation of AX and BX with the occurrence and nonoccurrence of the allergic reaction rose from .00 to 1.00, ratings of the distinctive A and B elements diverged; most importantly, ratings of the common X element fell. These causal judgments of humans closely parallel the conditioned responses of animals in associative learning studies, and clearly disclose that stimuli compete with one another for control over behavior.

It is now well known that the retention of newly-acquired information can be modulated by drugs or hormones administered shortly following training. It is generally thought that such treatments influence retention by modifying processes underlying the storage of information. The fact that susceptibility to posttraining memory modulation is seen in many species, including bees, fish, birds, and mammals, argues that some common time-dependent memory storage processes have been conserved in evolution. Recent research findings have provided strong support for the view that such susceptibility to posttraining influences provides opportunity for modulation of memory storage by endogenous neurohormonal systems. In rats and mice, posttraining administration of hormones such as epinephrine that are normally released by training experiences enhances subsequent retention. Comparable effects are found with posttraining administration of opiate receptor antagonists such as naloxone. Findings of recent experiments indicate that these treatments affect memory by influencing the release of norepinephrine within the amygdaloid complex. The endogenous regulation of memory storage appears to involve interaction of neurohormones and transmitters in activating brain systems involved in memory storage.

Recent experiments indicate that peripheral glucose administration enhances memory in rodents and humans. This study examined the effects of glucose on memory and nonmemory measures of neuropsychological functioning in elderly humans. Healthy older adults were given a series of neuropsychological tests after drinking glucose- or saccharin-flavored lemonade. A repeated measures design using counter-balanced beverages and tests was used. Glucose enhanced performance on declarative memory tests but not on short-term or nonmemory neuropsychological measures. Glucose tolerance predicted performance on declarative memory tasks but not on other measures.