I: Effect of delayed auditory feedback on speech and keytapping

The effects of delayed auditory feedback (DAF) on the performance of simple speech and keytapping tasks were compared. In the first experiment, each of the fourteen young adult subjects was asked to repeat the speech sound “b” in groups of three sounds. The subject heard his undelayed speech sounds through earphones. Under the delay condition, the speech sounds were delayed 244 millisec. before being returned to the subject's earphones. In the second experiment, each of the same subjects was asked to tap on a key in groups of three taps. The subjects heard an undelayed click through earphones each time they tapped on the key. Under the delay condition, the clicks were delayed 244 millisec. before being returned to the earphones. Graphic recordings were made of the time and intensity characteristics of tapping under both conditions.

The changes which occurred in speech and keytapping under DAF were qualitatively the same and consisted of increases in intensity and unit-to-unit time of both taps and speech sounds. When performing under DAF, the subjects also exhibited a tendency to repeat more sounds or to tap more times than had been requested. The percentage of change in intensity and time characteristics for speech and keytapping performances which occurred under DAF were not significantly different for the two motor systems. The amount of change in speech performance under DAF did not correlate significantly with the amount of change in keytapping performance.     

The calculation of sums of squares for interactions in the analysis of variance

A method is described for the calculation of the sum of squares for a second-order interaction. It is then shown that the method is general and can be used for the calculation of the sum of squares for any higher-order interaction.     

Resolving arguments accurately

This empirical investigation examined how ordinary language users resolved disagreements over the solutions to categorical syllogisms. Forty-six participants completed puzzles in logic. After completing the puzzles, participants were then randomly paired into 23 to compare their answers and to resolve 159 disagreements. Results indicate that the most frequently used strategies for resolving disagreements centered on: (a) arguing over the merits of the position (47% of the time) and (b) appealing to past solutions as a means of addressing current disputes (28% of the time). In addition, the data revealed that the most frequently used strategy (arguing the merits of the positions) was no more effective than random choice (52% increase in correct solutions) while the strategy of appealing to past solutions significantly aided dyads in reaching correct solutions (70% increase in correct solutions).     

School-based prevention of teen-age pregnancy and school dropout: Process evaluation of the national replication of the teen outreach program

Examined a program designed to prevent adolescent pregnancy, school failure, and dropout using a process model of evaluation to assess with which groups of participants and under what conditions the program was most effective. Students in the Teen Outreach Program of the Association of Junior Leagues and matched comparison students in 35 schools nationwide participated. Sites that highly utilized a volunteer service component, and sites that primarily served older students reported lower levels of student problem behaviors at program exit, after controlling for problem behaviors at entry. These findings occurred only for program youths and not for comparison youths. The connection of volunteer service to reductions in adolescent problem behaviors is interpreted in terms of helper-therapy and empowerment theories. Limitations of the analytic strategy used in this study, as well as techniques for addressing the limitations, are also discussed.     

On conditioned reinforcing effects of negative discriminative stimuli

Observing responses by pigeons were studied during sessions in which a food key and an observing key were available continuously. A variable-interval schedule and extinction alternated randomly on the food key. In one condition, food-key pecking during extinction decreased reinforcement frequency during the next variable-interval component, and in the other condition such pecking did not affect reinforcement frequency. Observing responses either changed both keylight colors from white to green (S+) or to red (S−) depending on the condition on the food key, or the observing responses never produced the S+ but produced the S− when extinction was in effect on the food key. Observing responses that produced only S− were maintained only when food-key pecking during extinction decreased reinforcement frequency in the subsequent variable-interval component. The red light conformed to conventional definitions of a negative discriminative stimulus, rendering results counter to previous findings that production of S− alone does not maintain observing. Rather than offering support for an informational account of conditioned reinforcement, the results are discussed in terms of a molar analysis to account for how stimuli acquire response-maintaining properties.     

On the role of word frequency in the detection of component letters

The experiments reported in this study were conducted to explore the issue of race models versus holistic models of word processing. In both types of model, it is assumed that an available word-level encoding for a display will conceal letter information, and thereby inhibit component-letter detection. However, whereas in holistic models it is assumed that encoding always should occur at the word or pattern level first, in the race models it is assumed that encoding occurs at all levels (e.g., feature, letter, and word) simultaneously, with the final level of encoding being at whatever level has been completed first. If the rate of word-level encoding is facilitated by increasing word frequency, the holistic models predict a generally declining latency for letter detection, because the initial step in letter detection (i.e., word-level encoding) will be occurring more rapidly. The race models, on the other hand, predict that with increasing word frequency there will be an increasing chance that the word-level encoding will win the encoding race, resulting in an increase in the latency for letter detection (i.e., the word code will conceal the letter codes). Two experiments are reported, and the obtained pattern of latency data appears to be most consistent with the race models.     

Effects of nutritional and mechanical properties of food on ruminative behavior.

Previous studies have identified a reliable relation between the quantity of food ingested and ruminating in profoundly retarded individuals and have established some parametric characteristics of this relation. The present study investigated three different properties of food that may influence this relation. Experiment 1 examined the role of stomach distention produced by including in the subject's diet wheat bran in amounts equivalent to and exceeding the calculated amount of crude fiber in the starch-satiation diet reported by Rast, Johnston, Drum, and Conrin (1981) and Rast, Johnston, and Drum (1984). There was a decrease in ruminating, although this decrease was smaller and more gradual than in the starch-satiation condition. Experiment 2 showed that increasing calories without increasing food volume resulted in a gradual and moderate decrease in ruminating. Experiment 3 replicated and extended the first two experiments by varying both caloric intake and stomach distention as well as oropharyngeal and esophageal stimulation in a different sequence of conditions. All variables exerted some control over responding. However, the large and immediate effects of the starch-satiation procedure occurred only when subjects were permitted to consume unlimited quantities.