Effect of classical conditioning on an internal clock

Six experiments with rats used a psychophysical choice procedure to study the internal clock used to discriminate duration. They investigated if the clock is sensitive to the signal value (associative strength) of a stimulus. The experiments involved two types of trials. On choice trials, a stimulus lasted a short (e.g., 3 s) or long (e.g., 12 s) duration; then the rats chose between two levers. The rewarded choice depended on the duration of the stimulus. On conditioning trials, the stimulus used on choice trials was presented, but it ended without food (extinction trials) or with food (pairing trials) regardless of what the rat did. The main stimulus minus accuracy with the long stimulus. Experiment 1 showed that extinction trials increased short bias relative to training without conditioning trials or to training with pairing trials. The rest of the experiments tested explanations of these results. The same results were found when extinction trials were the same duration as the short stimulus (Experiment 2), when extinction trials were a random duration (Experiment 5), and when the signal value of the conditioned stimulus was changed in another way (Experiment 6). The effect of conditioning trials was modality specific (Experiments 3 and 4). Of the explanations considered, the best one--the only one not contradicted at least once--is that changing the signal value of a stimulus changes how the clock times the stimulus. Reducing signal value reduces the measured duration.     

Reflex modification in the rat: the inhibitory effects of intensity and frequency changes in steady tones

In laboratory rats (as in humans) a low-intensity tone that precedes a high-intensity burst of noise by approximately 100 ms can reduce the amplitude of the startle reaction elicited by the burst of noise. A series of four experiments with rats investigated the relation between the inhibitory effects of tonal frequency change and the length of the silent period (gap) preceding it. The major findings were the following: (a) A gap in an otherwise continuous pure tone inhibited startle when the gap occurred approximately 100 ms prior to the noise burst. (b) Although an increase in gap duration increased the inhibition afforded by the gap, the maximum inhibition was yielded by gaps of 100 ms and greater; this maximum was equivalent to the inhibition yielded by the presentation of a postgap tone alone. (c) A shift in tonal frequency across a 10-ms gap yielded more inhibition than did the same gap with no frequency shift; again the shift yielded equivalent inhibition to the presentation of the postgap tone alone. (d) An increase in the frequency shift increased inhibition when the shift occurred across a 10-ms gap, but not when the shift occurred across a 100-ms gap.     

Deep dyslexia in childhood?

Deep dyslexia is an acquired reading disorder in which semantic substitutions (e.g., city read as town) are made in reading single isolated words. In this paper, evidence for deep dyslexic-type errors is presented from the word-recognition responses of six children, aged 7 years and 0 month to 8 years and 9 months, with severe reading disorders. These semantic substitutions occur in the absence of phonological skills. Therefore, it appears that there exists a small subset of developmental dyslexics who at the beginning of acquisition of reading skills are able to engage in semantic processing, but who show severe impairment of phonological processing. The existence of these reading errors indicate that the use of a phonological code is not necessary to extract meaning from the printed word.     

Clinician attitudes toward stuttering: A decade of change (1973–1983)

The attitudes of 674 speech-language pathologists toward stuttering, stutterers, stuttering therapy, parents of stutterers, and related issues were studied during the years 1973–1983. During that period, clinician attitudes were found to shift away from support of the John-sonian concepts, which suggest parental causality and dangers in early intervention. In addition, clinicians became less likely to perceive stutterers as possessing psychologic disorders and misperceptions of their problem and of their interpersonal relationships. However, a significant number of clinician's were found to continue to hold unsubstantiated beliefs regarding the personality of stutterers, their parents, and the efficacy of early intervention with very young stutterers. The results of the study were interpreted as suggesting the need to educate fluency specialists.     

Vowel duration in stutterers participating in precision fluency shaping

The purpose of this study was to determine the extent to which stutters manipulate vowel duration to achieve fluency after participating in Precision Fluency Shaping. Nine stutterers who read an all-voiced sentence fluently before and after therapy were selected for study. Wide-band spectrograms were made of the initial phrase of the sentences, and vowel durations were computed. Results indicated that extended vowel durations were characteristic of the fluency of stutterers posttherapy. The subject that had the highest rate of disfluency after therapy also had the shortest vowel durations. Clinical implications concerning the importance of speech rate during carryover practice are made.     

Group differences in intelligence and speed of information-processing

Three samples of different levels of mental ability, but each of average or above- average intelligence, were administered a battery of reaction time test which measure the speed with which persons can execute various elementary cognitive processes. Discriminant analyses revealed significant differences between the groups in reaction times and intraindividual standard deviations, and univariate analyses indicated that higher ability groups tended to obtain significantly faster mean reaction times and to show significantly less intraindividual variability than lower ability groups. Groups which differed the most in mental ability differed to the greatest extent on the more complex reaction time tests but this pattern was reversed for groups which were relatively close in mean IQ. Generally, the results support the hypothesis that speed- of-processing is an important factor unferlying intelligence, but a number of puzzling findings indicate the need for continued research in this area.     

Early adolescent egocentrism: a review of six articles

This paper reviews six articles which appear to be representative of the past fifteen years during which researchers have focused on early adolescent egocentrism. Each article is described in chronological order and compared to research findings suggested by the other articles. Although the researchers have suggested some interesting associations, there is a lack of consistency among their findings. The author indicates methodological problems and questions for further research which arise from the reviewed articles.     

Young adults' contraceptive practices: an investigation of influences

This study investigated young adults' contraceptive behaviors and attitudes through application of a comprehensive, theoretical framework. Specifically, a social-psychological approach to understanding preventive behaviors (e.g., contraceptive practices), was developed, incorporating the Health Belief Model and other factors, which offered a means for evaluating the extent to which contraceptive behaviors were influenced by individual and group characteristics. The study group consisted of 283 unmarried students at several schools who were, on average, 19 years of age. Results suggested that effective contraceptive behavior associated most strongly with respondents' perceiving relatively few barriers to their use of contraception, their maintenance of extensive interpersonal skills, and their regarding peer norms as consistent with effective contraceptive behavior. Findings also underlined a need for continuing education about sexuality and contraception. Dangerous misinformation prevailed regarding respondents' knowledge of areas that include anatomy, physiology, and appropriate use of effective contraceptive methods. Finally, results implied a need to consider broad behavioral, social, and interpersonal issues as they relate to young adults' effective contraceptive behavior. Future studies of contraceptive risk taking are encouraged to examine both individual and social factors affecting sexual and contraceptive practices if unplanned pregnancy is to be minimized, if not eliminated.     

Visual information processing speed in hypnotized and nonhypnotized subjects

Using a backward-masking paradigm with a bias-free and ceiling-free psychophysical task, we tested hypnotized and control subjects for speed of visual information processing. Approximately half of each group received visual imagery suggestions in an attempt to influence attention. Imagery produced no significant differential effect. Although an absence of a hypnotizability-performance relationship was in keeping with findings of a previous study, those subjects in the present study who performed under hypnosis were, as a group, significantly superior to the other subjects in speed of information processing.