Stress in time

The goals of this research were to determine whether speakers adjust the stress patterns of words within sentences to create an alternation between strong and weak beats and to explore whether this rhythmic alternation contributes to the characteristics stress differences between two major lexical categories of English. Two experiments suggested that speakers do alter lexical stress in accordance with rhythmic biases. When speakers produced disyllabic pseudowords in sentence contexts, they were more likely to place stress on the first syllable when the pseudoword was preceded by a weak stress and followed by a strong one than when the strong stress preceded and the weak followed. This occurred both when the pseudowords served as nouns and when they served as verbs. Text analyses further revealed that weakly stressed elements precede nouns more often than verbs, whereas such elements follow verbs more often than nouns. Thus, disyllabic nouns are more likely than disyllabic verbs to occupy contexts biased toward trochaic rhythm, a finding consistent with leftward dominant stress in disyllabic English nouns. The history of stress changes in English nouns and verbs also conforms with the view that rhythmic context may have contributed to the evolution of stress differences. Together, the findings suggest that the citation stress patterns of words may to some degree reflect adaptations of lexical knowledge to conditions of language performance.     

Multiunit changes in hippocampus and medial geniculate body in free-behaving rats during acquisition and retention of a conditioned response to a tone

Multiunit activity (MUA) was recorded chronically in the hippocampus (CA3) and the medial geniculate body (mMG) during habituation to a tone followed by conditioning (tone paired with footshock) or pseudoconditioning (tone/footshock unpaired) in rats previously trained in a lever-pressing for food task (VI 60). In the conditioned group pairing tones with footshocks rapidly induced an increase in the initial CS-evoked response in the mMG, followed by the emergence of a hippocampal response and a marked conditioned suppression of lever-pressing to the tone. In contrast, in the pseudoconditioned group, the stimulus induced only transient cellular changes in the hippocampus and in the mMG, while no behavioral suppression to the tone could be seen. Moreover, presentations of the CS 45 days later induced multiunit and behavioral responses in both structures, only in the conditioned group. These results are used for discussion of the role of learning-induced changes in the sensory structure (mMG) as compared with changes in an associative structure (hippocampus), during acquisition and retention of a conditioned response.     

Psychoneurogenic stress influences upon retention of an inhibitory avoidance response in the rat

Hormones and peptides involved in the response of an organism to stress play a modulating role in learning and memory processes. We studied whether psychoneurogenic stressors such as sound stimulation or novelty influence retention of an inhibitory avoidance response. An impairing effect on retention was observed when these stressors were applied shortly after the acquisition trial, but not after a 3-h delay. However, sound stimulation and novelty applied shortly before the retention test may facilitate retention behavior. It is suggested that the effect of psychoneurogenic stressors on retention behavior may be linked to influences on consolidation and retrieval processes mediated through the neurohumoral response of the organism to stress.     

Learned helplessness in the cockroach (Periplaneta americana)

For 3 consecutive days cockroaches (Periplaneta americana) were exposed to either escapable, inescapable, or no shock in an escape task. Twenty-four hours later they were tested in a shuttlebox escape task. There were reliable differences between escapable and inescapable animals and between inescapable and control animals in both escape latencies and the number of failures to escape.     

Isolation-dependent enhancement of 2-[14C]deoxyglucose uptake in the forebrain of zebra finch males

In a previous study (H. J. Bischof & K. Herrmann (1986), Behavioral Brain Research, 21, 215-221) we demonstrated that four forebrain areas of the zebra finch male are activated in situations which arouse the animal, for example when the birds are chased around the cage or when they are exposed to a female. These areas, the hyperstriatum accessorium-dorsale (HAD), a part of the medial neo-hyperstriatum (MNH), the lateral neo-hyperstriatum (LNH), and a portion of the caudal archi-neostriatum (ANC), show enhanced 2-[14C]deoxyglucose (2-DG) uptake according to the experimental situation. On the basis of these experiments, we examined whether the activation of the areas is correlated with motor activity and is influenced by different isolation times prior to a 2-DG experiment, where courtship of the male birds is elicited by exposing them to a female zebra finch. For this purpose, we isolated male zebra finches for 1 day, 1 week, or 8 weeks, respectively, before we injected the 2-DG and exposed the birds to a female. During the experiment, besides other activities, the number of song motifs performed by the bird and the frequency of changing perches was recorded. Our experiments demonstrate that there is a weak negative correlation between motor activity and 2-DG uptake, and a positive correlation between isolation time and 2-DG uptake. We suggest that long isolation blocks courtship behavior by some unknown mechanisms, and that the "internal drive" of the animal, which possibly corresponds with the activity of the four forebrain areas, is enhanced by isolation and by the fact that the birds do not perform the consummatory behavior. Our results also demonstrate that the 2-DG method can show up small differences in the internal state of an animal, which cannot easily be detected by behavioral measurements.     

Additivity, subadditivity, and the use of visual information: a reply to Massaro (1988)

Previously we (Bruno & Cutting, 1988) explored the perception of spatial relations among objects laid out in a computer-generated environment. In his commentary on our article, Massaro (1988) raised several issues. The most important is from his reanalysis, which indicated that--because of a subadditive trend in the results--additive and multiplicative strategies fit our data in Experiment 1 about equally well. In reply, we performed a different analysis. Results corroborate subadditivity--and hence multiplicative information combination--in Experiment 1 but provide no evidence for it in Experiments 2 and 3. On the whole, then, the results still support additivity more strongly than any other combination rule and thus support our notion of minimodularity.     

Cerebral hemispheric mechanisms in the retrieval of ambiguous word meanings

Targets related to ambiguous primes were projected to the left and right visual fields in a lexical priming experiment with stimulus onset asynchronies (SOA) of 35 and 750 msec. Right visual field results were similar to our earlier results with central projection (G. B. Simpson & C. Burgess, 1985, Journal of Experimental Psychology: Human Perception and Performance, 11, 28-39). Facilitation was found for the more frequent meaning at both SOAs and a decrease in facilitation for the less frequent meaning at the longer SOA. In contrast, left visual field results indicated a decay of facilitation for the more frequent meaning at the longer SOA, while activation for the subordinate meaning increased. Results suggest that, while automatic processing occurs in both hemispheres, only the left hemisphere engages in controlled processing of ambiguous word meanings. In addition, the present results support the idea that the right hemisphere has a special role in ambiguity resolution and that the right hemisphere lexicon possesses a richer endowment than earlier thought.     

Nonverbal communication as a compensative strategy for severely nonfluent aphasics? A quantitative approach

Seven severely nonfluent aphasics and one relative or close friend were investigated in an interview situation. The conversation was videotaped and analyzed for the use of nonverbal communication between aphasic and partner. The results indicate that the group of aphasics used significantly more frequently and for a significantly longer period of time nonverbal channels of communication than their healthy partners. The aphasic patients also used significantly fewer speech-focused movements and significantly more codified gestures. Nonverbal elements were more frequently used as speech substitutes by the group of aphasics.     

Fragile X speech phonology in Finnish

Fragile X syndrome is a recently discovered relatively common syndrome linked with an anomaly of the X chromosome and causing handicaps of cognitive development especially in males. In the present phonological analysis we will discuss the sound patterns of two Finnish fragile X speakers, a five (borderline intelligence)- and an eight (mildly mentally retarded)-year-old boy. The fragile X syndrome is not necessarily linked with any anomalies of speech organs. The subjects could produce all Finnish speech sounds in isolated test words. However, in the present samples of connected speech they exhibited general dysphonology. What is noteworthy is that their phonological error patterns resembled each other to a great extent. Among the common features were the tendencies to substitute and omit phonemes. As for vowels, our results showed about one-half of the errors to be omissions. Labiality and quantity oppositions were quite resistant to substitution. Most substitution errors of place of consonants occurred in dentals. As for the feature of manner, /r/ and /s/ were the phonemes most prone for substitution. A tendency toward spirantization or /h/ sation was common for both patients. The number of additions was clearly lower than has been reported for English-speaking developmentally dyspraxic children and also for Finnish Broca's aphasics. The speech problems of our patients seemed to indicate higher level motor encoding problems of linguistic information rather than peripheral articulatory deficits.     

The role of the right hemisphere in the production of linguistic stress

Recent research has proposed a general prosodic disturbance associated with right hemisphere damage (RHD), one encompassing both affective and linguistic functions. The present study attempted to explore whether the ability to produce linguistic prosody was impaired in this patient population. Productions of phonemic stress tokens (e.g., Re'dcoat vs. red coa't) as well as examples of contrastive stress, or sentential emphasis (e.g., Sam hated the movie), were elicited from eight male speakers with unilateral right hemisphere CVAs and seven male control subjects. Two types of analyses were conducted on these utterances. Acoustic analysis focused on the correlates associated with word stress, namely changes in amplitude, duration, and fundamental frequency. The perceptual saliency of emerging cues to stress was also examined by presentation of test tokens to phonetically trained listeners for identification of stress placement. The patients as a group produced fewer acoustic cues to stress compared to the normal subjects, but no statistical differences were found between groups for either stress at the phrase level or at the sentence level. In the perceptual analysis, stress produced by the patient group was judged to be less salient than that for the normal group, although a high degree of variability was evident in both populations. The data suggest a spared processing mechanism for linguistic prosody in RHD speakers, thus mitigating against the view of a general dysprosody tied to RHD.