A parametric analysis of the relationship between food quantity and rumination

Rumination is the chronic regurgitation, chewing, and reswallowing of previously ingested food. The study reported here, using a parametric design, examined the control of rumination by the quantity of food eaten at meals. The subjects were three profoundly retarded individuals who chronically emitted this behavior. The quantity of food by weight ingested daily was varied in 10-oz steps in both ascending and descending series (data were collected only after breakfasts and lunches). Ruminating decreased when food quantity increased and increased when food quantity decreased. In addition, there was a similar inverse interaction between breakfast food quantity and post-lunch ruminating. The data showed relatively rapid transitions in both frequency and duration at each meal size for all subjects. The data establish a clear functional relation between the quantity of food ingested and ruminating.     

Second-order schedules: a comparison of chained, brief-stimulus, and tandem procedures

Pigeons were exposed to seven types of two-component schedules, each component a 2-min fixed-interval schedule. Food presentation occurred at the completion of the second component under all conditions. The seven types of schedules were: (1) a chained schedule in which completion of the first component produced the discriminative stimulus associated with the second component; (2) a chained schedule to which was added the brief presentation of a food-paired stimulus at the completion of the first component; (3) a chained schedule to which was added the brief presentation of a stimulus not paired with food at the completion of the first component; (4) a multiple schedule in which food presentation occurred at the completion of both components; (5) a tandem schedule in which completion of the first component initiated the second component, with no changes in exteroceptive stimuli; (6) a food-paired brief-stimulus schedule in which the brief presentation of a food-paired stimulus was made at the completion of the first component and no other changes in stimuli occurred; and (7) a brief-stimulus schedule in which the brief presentation of a stimulus not paired with food was made at the completion of the first component and no other changes in stimuli occurred. Positively accelerated patterns of responding developed in the first component under three conditions: (1) the chained schedule with the added food-paired brief stimulus; (2) the multiple schedule; and (3) the food-paired brief-stimulus schedule. Response rates were low in the first component, with few instances of positively accelerated patterns, under two conditions: (1) the chained schedule; and (2) the chained schedule with the added nonpaired brief stimulus. The results suggest that a briefly presented food-paired stimulus may function as a more effective conditioned reinforcer than does the presentation of a discriminative stimulus.     

Modification of consonant speech-sound articulation in young children

A series of three experiments was performed in a classroom setting with small groups of young children with severe articulation problems. Variations on a basic token reinforcement procedure were demonstrated in each experiment. A combined multiple baseline/reversal design showed effective experimenter control of rates of correct and incorrect consonant sound articulation in all cases. In addition, the data in each experiment showed the problems of obtaining stimulus generalization of the high rates of correct articulation to non-training settings. The third experiment demonstrated a procedure for producing such generalization by making each child a discriminative stimulus for correct articulaton by the other child, thus maintaining high levels of correct articulation for each child when in the presence of the other.     

Asymmetry of masking between noise and tone

A pure tone was used to mask narrow and wide bands of noise centered on the frequency of the tone. In a given experimental session, the sound-pressure level (SPL) of the tone was held constant and loudness balances were obtained between a masked and unmasked noise band of equal width. These results are compared to earlier measures of the partial masking of tone by noise. The comparison shows that noise masks a tone more effectively than the tone masks the noise. Although the effect of the tone on a critical band of noise is greater than its effect on either an octave-band noise or wide-band noise, it is considerably smaller than the effect of the noise on the tone. Decreasing the noise bandwidth still further to a subcritical width reduces the asymmetry of masking somewhat, but a difference at high intensities of about 20 dB between the masking effects of an equally intense noise and tone remains. Whether the masker is a tone or noise, masking ceases when the effective energy of the masked and masking stimuli is the same.     

The analysis of performance criteria defining course grades as a determinant of college student academic performance

A series of five experimental conditions were designed to investigate the influence of minimum performance criteria and grade labels on college student academic performance. A college course in abnormal psychology was taught in an individualized manner so that each student could perform on each unit of subject matter in individual performance sessions whenever he wished. In each of the five experiments the minimum performance criteria that had to be attained before progressing to the next unit were varied during the quarter and the resulting changes in performance were recorded. In Experiment I there were no criteria; in Experiments II, III, and IV three levels of criteria (High, Medium, and Low) were varied but all of the criteria defined a course grade of "A". In Experiment V, the three criteria defined course grades of A, B, and C. The results showed that the criteria controlled performance to a high degree, so that regardless of what quality of performance had been demonstrated previously or was being produced currently, performance was immediately changed to attain new criteria put into effect. Students in Experiment I produced very poor performance compared to the other conditions.     

The role of familiar units in perception of words and nonwords

This paper investigates the effects of familiarity with whole-word units and letter-cluster units in perceptual encoding of letter strings. Subjects viewed brief, masked presentations of words and pronounceable pseudowords differing in letter cluster frequency. Identification of both display types was compared to control single letters. Perceptual accuracy was indexed by probe forced-choice responses and full verbal reports of the displays. Evidence that familiarity of whole-word units facilitated encoding was mixed but, on balance, favorable. Evidence that familiarity of letter-cluster units facilitated encoding was completely absent. This negative finding is surprising in view of the fact that we did obtain a large advantage of letters in pseudo-words as well as words over single letters. The discussion section considers an alternative to the view that perceivers use detectors for familiar letter-cluster units in the process of forming representations of pronounceable, orthographically regular letter strings.     

In defense of intraperceptual theories of attention

A distinction is drawn between intraperceptual and extraperceptual theories of attention. Only the former class allows for the selective modulation of amount of nonconscious, perceptual processing of concurrent stimuli. The adequacy of intraperceptual theory has been questioned on the basis of diverse empirical findings. This literature is critically examined and is considered inconclusive partly because of the lack of an appropriate measure of amount of perceptual processing. A new experiment that attempts to provide such a measure is reported. Subjects detected names of states of the United States in dichotically presented lists. Subjects either could focus on just one list (relevant list) or had to divide their attention between the two lists. Amount of perceptual processing of a word (e.g., voice or titre) was measured in terms of the extent to which it primed subjects' interpretations of a visually presented homograph (e.g., spoke). Priming potency of words was greatest in the relevant list and was least in the other list. The data support a broad version of intaperceptual theory that allows for birth perceptual facilitation of relevant stimuli and perceptual suppression of irrelevant stimuli.     

An illusion of ingestion

Three experiments were conducted to find out why subjects ingest substantially more liquid than required when asked to match a visually displayed volume. All three experiments replicated the basic illusion phenomenon, and Experiments 1 and 2 indicated that it was attributable to the subjects’ underestimating the volume of liquid in their mouths. Experiment 3 revealed that the illusion was not present with solid substances, but it was evident with liquids when a quite different measurement procedure was employed.