A COMPARISON OF TWO PROCEDURES FOR PROGRAMMING THE DIFFERENTIAL REINFORCEMENT OF OTHER BEHAVIORS

The relative effectiveness of two methods of programming DRO schedules of reinforcement was examined in two experiments. In these two methods, reinforcement is delivered if inappropriate responding is not occurring (a) at the end of an interval (momentary DRO), or (b) throughout the entire interval (whole-interval DRO). In Experiment 1, the effects of these schedules on disruptive responding of three retarded students were assessed in a multiple-baseline design. For two students, the momentary schedule occurred first and was ineffective, whereas the whole interval that followed was effective; for the third student, the whole-interval schedule occurred first and was effective, and reduced responding was maintained under the momentary schedule. In Experiment 2, baseline and the two DRO schedules were each presented in random order each day to one student in an alternating treatments design. The momentary DRO schedule reduced responding, but the whole-interval schedule was more effective.     

Decreasing classroom misbehavior through the use of DRL schedules of reinforcement

In three studies, reinforcing low rates of responding reduced inappropriate behaviors. In the first study, the talking-out behavior of one TMR student was reduced when the teacher allowed 5 min of free time for a talk-out rate less than 0.06 per minute. In a second study, the talking-out behavior of an entire TMR class was reduced when reinforcement was delivered for a response rate less than 0.10 per minute. In a third study, successively decreasing DRL limits were used to reduce off-task verbalizations of an entire high school business class. In each case, the DRL procedure proved manageable for the teacher and successful in reducing misbehavior.     

Probing the cognitive representation of musical time: structural constraints on the perception of timing perturbations.

To determine whether structural factors interact with the perception of musical time, musically literate listeners were presented repeatedly with eight-bar musical excerpts, realized with physically regular timing on an electronic piano. On each trial, one or two randomly chosen time intervals were lengthened by a small amount, and the score. The resulting detection accuracy profile across all positions in each musical excerpt showed pronounced dips in places where lengthening would typically occur in an expressive (temporally modulated) performance. False alarm percentages indicated that certain tones seemed longer a priori, and these were among the ones whose actual lengthening was easiest to detect. The detection accuracy and false alarm profiles were significantly correlated with each other and with the temporal microstructure of expert performances, as measured from sound recordings by famous artists. Thus the detection task apparently tapped into listeners' musical thought and revealed their expectations about the temporal microstructure of music performance. These expectations, like the timing patterns of actual performances, derive from the cognitive representation of musical structure, as cued by a variety of systemic factors (grouping, meter, harmonic progression) and their acoustic correlates. No simple psycho-acoustic explanation of the detection accuracy profiles was evident. The results suggest that the perception of musical time is not veridical but "warped" by the structural representation. This warping may provide a natural basis for performance evaluation: expected timing patterns sound more or less regular, unexpected ones irregular. Parallels to language performance and perception are noted.     

Bidirectional contrast effects in the perception of VC-CV sequences

The perceived places of articulation of two successive stop consonants are not independent: Given some ambiguity in the formant transition cues and a closure duration between 100 and 200 msec, contrastive perceptual interactions in both directions have been observed in identification tasks. Retroactive contrast declines as the closure interval is lengthened and is strongly influenced by the range of closure durations employed, whereas proactive contrast appears to be less sensitive to these factors (Experiment 1). Reduced contrast and no effects of closure duration are obtained in a discrimination task with selective attention to one stimulus portion; this suggests that the effects in identification arise largely at a higher level of (phonetic) perception (Experiment 2). The contrast effects do not seem to represent a perceptual compensation for coarticulatory dependencies between stops produced in sequence, for there appears to be little coarticulation as far as place of articulation is concerned (Experiment 3). The most plausible hypothesis is that the presumed contrast effects do not result from any direct interaction of spectral cues across the closure interval but are due to perceptual information conveyed by the closure itself: Closure durations of 100–200 msec happen to be most appropriate for sequences of two nonhomorganic stops. Here, it seems, is another case in which listeners’ tacit knowledge of canonical speech patterns determines perception.     

BEHAVIORAL ASSESSMENT OF FEEDING PROBLEMS OF INDIVIDUALS WITH SEVERE DISABILITIES

As many as 80% of the individuals with severe or profound mental retardation exhibit feeding problems. Although behavioral interventions have been used to treat these problems, no assessment procedure for determining a functional relationship between a person's acceptance of food and the type and texture of that food has been reported. The purpose of this study was to test a behavioral assessment procedure for a feeding problem of limited intake. Five individuals with severe or profound mental retardation were fed 10 to 12 types of foods with one or more textures. Behavioral categories of acceptance, rejection, expulsion, and other negative behavior were recorded. Results indicated that each subject fit into one of four categories of feeding problems: (a) total refusal, (b) type selectivity, (c) texture selectivity, or (d) type and texture selectivity. Thus, although all 5 subjects exhibited limited intake, the food characteristics correlated with the problem were different for each individual. Results suggest that treatments for limited intake may be based on assessments that show the association of food type or texture to a person's rejection or expulsion of food.     

Hearing a melody in different ways: multistability of metrical interpretation, reflected in rate limits of sensorimotor synchronization

Music commonly induces the feeling of a regular beat (i.e., a metrical structure) in listeners. However, musicians can also intentionally impose a beat (i.e., a metrical interpretation) on a metrically ambiguous passage. The present study aimed to provide objective evidence for this little-studied mental ability. Participants were prompted with musical notation to adopt different metrical interpretations of a cyclically repeated isochronous 12-note melody while tapping in synchrony with specified target tones in the melody. The target tones either coincided with the imposed beat (on-beat tapping) or did not (off-beat tapping). An adaptive staircase method was employed to determine the fastest tempo at which each synchronization task could be performed. For each metrical interpretation, a significant advantage for on-beat over off-beat tapping was obtained - except in a condition in which participants, instead of synchronizing, were in control of the target tones. By showing that a self-imposed beat can affect sensorimotor synchronization, the present results provide objective evidence for endogenous perceptual organization of metrical sequences. It is hypothesized that metrical interpretation rests upon covert rhythmic action.     

Do metrical accents create illusory phenomenal accents?

In music that is perceived as metrically structured, events coinciding with the main beat are called metrically accented. Are these accents purely cognitive, or do they perhaps represent illusory increases in perceived loudness or duration, caused by heightened attention to main beats? In four separate tasks, musicians tried to detect a small actual increase or decrease in the loudness or duration of a single note in melodies comprising 12 notes. Musical notation prescribed a meter (6/8) implying a main beat coinciding with every third note. Effects of metrical accentuation on detection performance were found in all four tasks. However, they reflected primarily an increase in sensitivity to physical changes in main beat positions, likely to be due to enhanced attention. There was no evidence of biases indicating illusory phenomenal accents in those positions. By contrast, and independent of metrical structure, pitch accents due to pitch contour pivots were often mistaken for increases in loudness.     

Book review

Journal of Behavioral Education -