Auditory apparent motion in the free field: The effects of stimulus duration and separation

The effects of stimulus duration and spatial separation on the illusion of apparent motion in the auditory modality were examined. Two narrow-band noise sources (40 dB, A-weighted) were presented through speakers separated in space by 2.5°, 5°, or 100, centered about the subject’s midline. The duration of each stimulus was 5, 10, or 50 msec. On each trial, the sound pair was temporally separated by 1 of 10 interstimulus onset intervals (ISOIs): 0, 2, 4, 6, 8, 10, 15, 20, 50, or 70 msec. Five subjects were tested in nine trial blocks; each block represented a particular spatial-separation-duration combination. Within a trial block, each ISOI was presented 30 times each, in random order. Subjects were instructed to listen to the stimulus sequence and classify their perception of the sound into one of five categories: single sound, simultaneous sounds, continuous motion, broken motion, or successive sounds. Each subject was also required to identify the location of the first-occurring stimulus (left or right). The percentage of continuous-motion responses was significantly affected by the ISOI [F(9,36) = 5.67,p < .001], the duration × ISOI interaction [F(18,72) = 3.54,p < .0001], and the separation × duration × ISOI interaction [F(36,144) = 1.51,p < .05]. The results indicate that a minimum duration is required for the perception of auditory apparent motion. Little or no motion was reported at durations of 10 msec or less. At a duration of 50 msec, motion was reported most often for ISOIs of 20–50 msec. The effect of separation appeared to be limited to durations and-ISOIs during which little motion was perceived.     

Small group therapy and preadolescent same-sex friendship

On the rationale that group psychotherapy focuses on interaction processes in close relationships, our study sought to investigate the hypothesis that small group therapy would be effective in enhancing intimate friendship in a dyadic relationship. The study group consisted of 102 elementary school students who had been referred for counseling help. Matched by age, sex, and similarity of problem, each pair of students was divided into an experimental group (N = 55) and a control group (N = 47). The experimental group contained eight small treatment groups and the control group contained seven matching small groups, leaving one special education group with no control. The results support our hypothesis that group psychotherapy positively affects intimate friendship of girls and boys. They further suggest the boys' need for such an experience, since without it they markedly deteriorate in intimate friendship. Implications for the group leader are derived from the correlations between gains in intimate friendship and group intimacy.     

Effects of Probabilistic Rewards on Recycling Attitudes and Behavior1

Two studies compared the attitudinal and behavioral effects of certain rewards and lotteries. In a laboratory experimental study, lotteries produced significantly more attitude change than cash payments. The greatest attitude change occurred among lottery winners. In a quasi-experimental field study, subjects rewarded with lottery tickets recycled glass and newspaper more frequently than subjects receiving other individual or group rewards. Attitude change was not affected by the type of reward Implications for the design of incentive programs to increase prosocial behavior are discussed     

Control over response number by a targeted percentile schedule: reinforcement loss and the acute effects of d-amphetamine.

Two fixed-consecutive-number-like procedures were used to examine effects of acute d-amphetamine administration on control over response number. In both procedures, rats were required to press the left lever at least once and then press the right lever to complete a trial. The consecutive left-lever presses on each trial comprised a "run." Under the targeted percentile schedule, reinforcement was provided if the current run length was closer to the target length (16) than half of the most recent 24 runs. This differentially reinforced run length while holding reinforcement probability constant at .5. A second group acquired the differentiation under the targeted percentile schedule, but were then shifted to a procedure that yoked reinforcement probability by subject and run length to that obtained under the targeted percentile schedule. The two procedures generated practically identical control run lengths, response rates, reinforcement probabilities, and reinforcement rates. Administration of d-amphetamine disrupted percentile responding to a greater degree than yoked control responding. This disruption decreased reinforcement frequency less in the former than the latter procedure. The similar baseline responding under these two procedures suggests that this difference in sensitivity was due to behavioral adjustments to drug prompted by reduction of reinforcement density in the yoked control but not the percentile schedule. These adjustments attenuate the drug's effects under the former, but not the latter, procedure.     

The role of instructions in the transfer of ordinal functions through equivalence classes

In two experiments, adult subjects completed match-to-sample training and testing to establish four equivalence classes of four figures each. Then the subjects were taught one three-position sequence consisting of one stimulus from Class 1, one from Class 2, and one from Class 3. Inclusion of Class 4 stimuli in sequences was never reinforced, but two different stimuli from Class 4 appeared as distractors on each sequence trial. Tests assessed whether subjects would produce novel three-position sequences composed of members of Classes 1 through 3 that had not been used in sequence training. Three subjects in Experiment 1 received instructions about the match-to-sample and sequencing tasks, in addition to training contingencies. All 3 demonstrated equivalence class formation after match-to-sample training. After they were taught one sequence with one member of Classes 1 through 3, none of these subjects produced untrained sequences with other equivalence class members reliably. One additional sequence was trained directly; thereafter 1 subject showed some evidence of transfer of the trained ordinal functions across the remaining members of the equivalence classes, but the other 2 did not. Following a review of equivalence class training and testing and a review of the original sequence training, all 3 subjects produced most of the predicted, untrained sequences on tests. Experiment 2 replicated Experiment 1 with 2 adults but omitted all instructions except the minimal ones necessary to initiate responding. Unlike the subjects in Experiment 1, both of these subjects demonstrated virtually complete transfer of ordinal functions through the equivalence classes after direct training on just one sequence composed of one member of Classes 1 through 3.     

Writing with the right hemisphere

We studied writing abilities in a strongly right-handed man following a massive stroke that resulted in virtually complete destruction of the language-dominant left hemisphere. Writing was characterized by sensitivity to lexical-semantic variables (i.e., word frequency, imageability, and part of speech), semantic errors in writing to dictation and written naming, total inability to use the nonlexical phonological spelling route, and agrammatism in spontaneous writing. The reliance on a lexical-semantic strategy in spelling, semantic errors, and impaired phonology and syntax were all highly consistent with the general characteristics of right hemisphere language, as revealed by studies of split-brain patients and adults with dominant hemispherectomy. In addition, this pattern of writing closely resembled the syndrome of deep agraphia. These observations provide strong support for the hypothesis that deep agraphia reflects right hemisphere writing.     

Filtering by movement in visual search.

Search for a target defined by a conjunction of movement and form (e.g., an X moving up in a display of intermingled Os moving up and stationary Xs) is parallel. This result is also found if (a) the moving Os and target X move in unpredictable directions so that the moving stimuli do not form a clear perceptual group or (b) the nontarget Xs also move but in a known, different direction from the Os and target X. In contrast, search is slow and serial if the target may be unpredictably among either moving or stationary stimuli. These results suggest that a component of the visual system operates as a movement filter that can direct attention to stimuli with a common movement characteristic. The filtering cue can be moving (vs. stationary), or movement in 1 particular direction. The results do not support the view that attention can only be directed to groups defined by common fate.     

Understanding: Art and science

The arts and the sciences perform many of the same cognitive functions, both serving to advance understanding. This paper explores some of the ways exemplification operates in the two fields. Both scientific experiments and works of art highlight, underscore, display, or convey some of their own features. They thereby focus attention on them, and make them available for examination and projection. Thus, the Michelson-Morley experiment exemplifies the constancy of the speed of light. Jackson Pollock'sNumber One exemplifies the viscosity of paint. Despite their similarities, science and art might seem to differ in their attitude toward facts. Science is said to adhere to facts; art, to be indifferent to them. Such, I urge, is not the case. Science, like art, often scorns fact to advance understanding through fiction. Thought experiments, I contend, are scientific fictions; literary and pictorial fictions, aesthetic thought experiments.This paper was first published in 1991, in Peter A. French, Theodore Uehling Jr., and Howard Wettstein (eds.),Philosophy and the Arts, Midwest Studies in Philosophy, Vol. XVI, University of Notre Dame, Notre Dame, pp. 196–208.     

Self-concept and sociometric outcomes: a comparison of only children and sibling children from urban and rural areas in the People's Republic of China.

We investigated differences in self-concept between 360 only children and 555 sibling children in the sixth grade of three urban schools and three rural schools in the People's Republic of China. Peer perceptions and teacher perceptions were also collected using sociometric measures. Self-concept was determined by the Self-Perception Profile for Children (Harter, 1985). Comparisons of sibling children and only children showed no differences on self-concept; however, urban residents had higher self-concept scores than children from rural areas, and boys scored higher than girls. No significant interaction effects between sibling status, gender, and residence were found.