The role of audition in infant babbling

The traditional belief that audition plays only a minor role in infant vocal development depends upon evidence that deaf infants produce the same kinds of babbling sounds as hearing infants. Evidence in support of this position has been very limited. A more extensive comparison of vocal development in deaf and hearing infants indicates that the traditional belief is in error. Well-formed syllable production is established in the first 10 months of life by hearing infants but not by deaf infants, indicating that audition plays an important role in vocal development. The difference between babbling in the deaf and hearing is apparent if infant vocal sounds are observed from a metaphonological perspective, a view that takes account of the articulatory/acoustic patterns of speech sounds in all mature spoken languages.     

Prosodic correlates of stress in babbling: an acoustical study

Prelinguistic babbling often seems remarkably speech-like, not because it has recognizable words but because it seems to have adult-like prosody. To quantify this impression, we compared disyllabic sequences from five infants and five adults in terms of the use of frequency, intensity, and duration to mark stress. Significantly larger values for the three acoustic variables were observed on stressed than on unstressed syllables independent of syllable position for both groups. Adults showed the correlates of utterance final syllables--lower f0, lower intensity, and longer duration; infants showed only decrease in intensity. Ratios for stressed to unstressed syllables and participation of the three variables in stress production in individual disyllables were highly similar in both groups. No bias toward the English lexical trochaic stress pattern was observed. We conclude that infants in English environments produce adult-like stress patterns before they produce lexical items, which specify stress. Acoustic and perceptual analyses are used to explore stress marking by prelinguistic infants in an English language environment. Results show that infants employ the three acoustic correlates of stress in individual syllables in a manner largely similar to that of adult speakers, although they do not show second-syllable declination effects or an English language trochaic stress bias.     

Social attachment of the infant guinea pig to its parents in a two-choice situation

Twenty-four domestic guinea pigs (12 of each gender) served as subjects in this study, which investigated attachment by testing amount of time (maximum 5 min) the infants spent close to either the mother or the father in a two-choice situation during Weeks 2, 4, 6, and 8 after birth. Significantly more time was spent close to the mother during Weeks 2 and 4; reaction to the father appeared random. Time spent close to the mother declined across weeks, suggesting that maternal attachment weakens as the infant matures.     

Social support, infant temperament, and parenting self-efficacy: a mediational model of postpartum depression

A model of maternal postpartum depression was tested in which difficult infant temperament was construed as a stressor and supportive interpersonal relationships were construed as a protective resource. It was hypothesized that both infant temperamental difficulty and level of social support would affect maternal depression through the cognitive mediation of perceived self-efficacy in the parenting role. Participants were 55 married women who were assessed during pregnancy and again 3 months postpartum. Infant temperament was assessed through observation, maternal crying records, and the Revised Infant Temperament Questionnaire. Results of a path analysis indicated that infant temperamental difficulty was strongly related to the mothers' level of postpartum depression, both directly and through the mediation of parenting self-efficacy. Consistent with predictions, social support appeared to exert its protective function against depression primarily through the mediation of self-efficacy. Both practical implications for identifying women at risk for postpartum depression and theoretical implications for understanding the mechanisms through which stressful events and social support affect adjustment are discussed.     

Signal properties of reinforcement and reinforcement omission on a multiple fixed-ratio schedule

A series of experiments used food-deprived pigeons to examine several parameters of reinforcement omission in an attempt to control changes of keypeck response measures on a subsequent schedule. In Experiments 1 and 2, the pigeons were tested with a multiple fixed-ratio schedule on which reinforcement was occasionally omitted at the completion of the first component. The duration of the delay occurring in lieu of reinforcement was systematically varied. In Experiment 3, the stimulus that signaled the second component of the schedule was altered to appear either more or less similar to the stimulus that signaled the first component. Two principal results are reported: (1) Response latency decreased and, to a much lesser extent, terminal response rate increased as the delay occurring in lieu of reinforcement decreased; and (2) both latency decrease and response-rate increase were enhanced by a second component stimulus which was similar to the first. The results are evaluated in terms of Amsel’s frustration theory and an analysis by Staddon which suggests that reinforcement inhibits responding. The data appear to support Staddon’s argument that rate increases and latency decreases following reinforcement omission are largely a function of an attenuation of the inhibitory influence of reinforcement, an effect that is enhanced by stimulus generalization. Accordingly, it is proposed that an animal’s response to reinforcement omission is determined by a stimulus complex that minimally includes the omission event and component cues.     

Preference for 50% reinforcement over 75% reinforcement by pigeons

When pigeons are given a choice between an initial-link alternative that results in either a terminal-link stimulus correlated with 100% reinforcement or a stimulus correlated with 0% reinforcement (overall 50% reinforcement) and another initial-link alternative that always results in a terminal-link stimulus correlated with 100% reinforcement, some pigeons show a preference for the initial-link alternative correlated with 50% reinforcement. Using this procedure, in Experiment 1, we found a relatively modest preference for 100% over 50% reinforcement. In Experiment 2, we decreased the reinforcement density for the second initial-link alternative to 75% and found a significant preference for the 50% reinforcement initial-link alternative. It may be that this “maladaptive” behavior results from a positive contrast between the expectation of reinforcement correlated with the 50% reinforcement initial-link alternative and the terminal-link stimulus correlated with 100% reinforcement. But apparently, the complementary negative contrast does not develop between the expectation of reinforcement correlated with the 50% reinforcement initial-link alternative and the terminal-link stimulus correlated with 0% reinforcement that often follow. Such paradoxical choice may account for certain human appetitive risk-taking behavior (e.g., gambling) as well.     

The context for reinforcement: Modulation of the response-reinforcer relation by concurrently available extraneous reinforcement

Learning & Behavior - Right-lever presses by hooded rats in three groups produced reinforcers at variable-intervals that differed over five conditions. The groups differed by virtue of the...     

Durability of the partial reinforcement and partial delay of reinforcement extinction effects after minimal acquisition training

Four groups of 10 rats each were given six acquisition trials (Phase 1) under continuous reinforcement (CR), partial reinforcement (PR), constant delay (CD), or partial delay of reinforcement (PD) conditions. In Phase 2, all Ss were given 18 nonreinforced trials, followed by 12 continuously reinforced trials in Phase 3. In Phase 4, all Ss were given 12 more extinction trials. A constant 24-h ITI was observed throughout the experiment. A strong partial reinforcement extinction effect (PREE) was obtained in both Phases 2 and 4. Only a temporary partial delay of reinforcement effect (PDRE) was observed, which was restricted to the first nine trials of the first extinction phase. No constant delay of reinforcement effect (CDRE) was observed in either extinction phase. The results were discussed in terms of both frustration and sequential theories.     

Integration of reinforcement effects over time

Two accounts of how density of reinforcement affects steady-state performance on probabilistic schedules were compared: the real-time linear operator (RTLO) model and a temporal control model (in which response strength is determined by reinforcement probability as a function of postreinforcement time). In Experiment 1, the probability of reinforcement repeatedly cycled between extinction and a random-ratio 10 schedule. Response-rate gain and phase did not change with period of the cycle as predicted by the RTLO model, nor did either model predict the differences in response rate following reinforcement at different points in the cycle. In Experiment 2, the probability of reinforcement was elevated immediately following a reinforcement but fell after a few seconds. Previous reinforcements had no effect upon responding. An extension of the temporal control model, the cumulative impulse model, allowed for the summing of response strength over successive reinforcements and was consistent with the data of both experiments.     

Holland environments as reinforcement systems

Holland's (1973, 1985) theory of vocational choice stipulates that model environments seek toreinforce the characteristic predispositions and attitudes of their corresponding personality types. The results of this longitudinal study of the self-perceptions of more than 2,000 graduates from eight types of colleges and universities (Carnegie Commission, 1971) generally support the validity of this premise. For example, graduates prepared in investigative environments have higher intellectual self-esteem scores and those prepared in artistic environments have higher artistic self-esteem scores, when pre- and postcollege measures are controlled. These general patterns are consistent for graduates from the eight institutional types. The implications of these findings are discussed for those who study the intra- and interinstitutional diversity of colleges and universities and their differential impact on student developmental patterns.     

Behavioral contrast and reinforcement value

Behavioral contrast was produced in two target components of a four-component multiple schedule by having two target stimuli followed either by a higher rate of reinforcement or by extinction. Response rate was higher in the target followed by extinction. Periodic probe trials were then presented in which the two target stimuli were presented together. Choice on these probe trials was in favor of the stimulus followed by the higher rate of reinforcement during regular training. Experiment 2 replicated this finding but with probe trials presented throughout training. Here, preference for the stimulus followed by the higher rate of reinforcement was evident early in training, substantially before the contrast effects developed. The results challenge interpretations of contrast based on the concept of relative value.     

Preference reversal and delayed reinforcement

Pigeons chose, in a two-key discrete-trial procedure, between 2- and 4-sec access to grain, with the larger amount always presented 4 sec later than the smaller. As the delay between the choice and the availability of the smaller reinforcement was varied from .01 to 12 sec, all subjects reversed preference from the small-early to the large-late reinforcement. The values of delay at which preference reversed were approximately consistent with the matching law as adapted for delayed reinforcement.     

Infant and preschool reinforcement survey

An empirically developed infant and preschool reinforcement survey was completed by 35 parents and 21 children. Test-retest reliability coefficients were computed on these data after a one-week interval. The development of the survey, as well as its usefulness for school psychologists, is described.