Motor learning without physical practice: The effects of combined action observation and motor imagery practice on cup-stacking speed

In this study we explored training effects for combined action observation and motor imagery (AO + MI) instructions on a complex cup-stacking task, without physical practice. Using a Graeco-Latin Square design, we randomly assigned twenty-six participants into four groups. This counterbalanced the within-participant factor of practice condition (AO + MI, AO, MI, Control) across four cup-stacking tasks, which varied in their complexity. On each of the three consecutive practice days participants experienced twenty trials under each of the three mental practice conditions. On each trial, a first-person perspective video depicted bilateral cup-stacking performed by an experienced model. During AO, participants passively observed this action, responding only to occasional colour cues. For AO + MI, participants imagined performing the observed action and synchronised their concurrent MI with the display. For MI, a sequence of pictures cued imagery of each stage of the task. Analyses revealed a significant main effect of practice condition both at the ’surprise’ post-test (Day 3) and at the one-week retention test. At both time points movement execution times were significantly shorter for AO + MI compared with AO, MI and the Control. Execution times were also shorter overall at the retention compared with the post-test. These results demonstrate that a complex novel motor task can be acquired without physical training. Practitioners can therefore use AO + MI practice to supplement physical practice and optimise skill learning.     

Value and uncertainty as weighting factors in impression formation

An experiment was conducted to compare mathematical models describing how people combine information to form an impression of another person. Subjects rated how much they would like stimulus persons described by one or two adjectives. Subjects also reported their level of uncertainty about each evaluation. Models using the uncertainty measures to predict integration weights were no more successful than the equal weight averaging model. There was no evidence that extreme adjectives were given high weight. Information integration was best described by a model in which the more negative adjective in a pair is given more weight than the other adjective.     

Eliminating selective stimulus control: a comparison of two procedures for teaching mentally retarded children to respond to compound stimuli

Selective stimulus control occurs when behavior fails to come under control of all characteristics of a compound stimulus after discrimination training. Two different assessment procedures, one used in prior research and the other incorporating incorrect stimuli (S - 's) which differed minimally from the correct stimulus (S+), were used to detect stimulus control deficits characteristic of selective stimulus control. The efficacy of two training procedures in eliminating selective stimulus control observed with three trainable mentally retarded children was evaluated in Experiment 1. A training procedure using S - 's that were minimally different from the S+ was designed to reduce the probability that stimulus discriminations could be based on stimulus characteristics other than experimenter-specified characteristics defining the S+. This procedure proved more effective in preventing and eliminating selective stimulus control as measured by both assessment procedures than an alternate discrimination training procedure that failed to impact the more stringent measures of selective stimulus control. Experiment 2 indicated that these improvements in stimulus control were not a function of varying degrees of difficulty between stimulus sets or of a prior history of discrimination training with the less effective training procedure. The need for better assessment procedures to detect selective stimulus control and suggestions for further improvements in discrimination training procedures are discussed.     

Phonemic awareness and spelling: children's judgments do not always agree with adults

The ability to make explicit judgments about speech sounds is important in learning to read and write an alphabetic system. However, even when children can make consistent judgments about sounds their judgments do not always agree with those of adults. In this study, some children from groups of kindergartners (mean age 5 years, 10 months) and first graders (mean age 6, 7) stated that /tr/ (as in "truck") did not begin with the sound /t/. This judgment was reflected in these children's spellings: They tended to spell /t/ before /r/ with CH, reflecting its affrication. Parallel results were found for /dr/. Further, some children judged that /c/ (as in "chill") and /j/ (as in "Jill") began with /t/ and /d/, respectively. They used the letters T and D to spell these sounds. Thus, children's attention to a phonetic level may result in judgments of speech sounds and spellings that are different from those of adults.     

The center and range of the probability interval as factors affecting ambiguity preferences

Ambiguous decision situations are characterized as having probabilities that are uncertain. The uncertainty is due to the common, real-world deficiency of information about the process by which the outcomes are determined. Thirty lotteries having uncertain probabilities were constructed by varying the centers and the ranges of the intervals within which the imprecise probabilities of winning could lie. Pairs of the lotteries were presented as choice alternatives to subjects, with each pair having lotteries with the same interval center but differing interval ranges. Ambiguity avoidance, the selection of the less ambiguous option, was found to increase with the interval center C, with ambiguity indifference occurring for values of C ? 0.40. No evidence of ambiguity seeking as the prevalent behavior was obtained. Ambiguity avoidance did not significantly increase with the interval range R, but an interaction effect between C and the ranges R₁ and R₂ of the choice pair was obtained. This effect of the ranges could not be described simply by knowledge of the difference R₁ ? R₂; knowledge of both individual values was necessary. The theoretical implications of these results are discussed.     

Organization revealed by recall orders and confirmed by pauses

The technique introduced here induces the organization of information in memory from systematic inspection of regularities in free recall. The form of the representation of this organization is an “ordered tree.” The technique has the advantage of being based on a theory of the way in which the data were generated and can be shown to produce a unique structure that captures all the kinds of regularities the theory of recall prescribes. Also presented is a collateral technique for measuring the amount of organization evidenced in a struture, as well as a procedure for identifying errors. The experimental work shows the technique's ability to recover the details of an organization presented to subjects and provides converging evidence for the particular structures induced from the pattern of recall pauses. In addition, the application of the technique to structures unknown a priori produced organizations that were easy to interpret and a second set of pauses that further confirmed the details of the induced structures.     

The development of communication: When a bad model makes a good teacher

Five experiments were conducted on what 6-year-old children learn about communication by switching listener and speaker roles with competent and incompetent adults and peers. Experiment I demonstrated that children become better communicators to adults after listening to competent adults, competent peers, and incompetent peers, but not incompetent adults. The age of the listener was shown to have an effect in Experiment II, with children becoming less effective communicators when speaking to a peer after listening to an incompetent peer but better communicators when speaking to an adult after listening to an incompetent peer. Experiments III, IV, and V were designed to determine why children do not improve or deteriorate after listening to incompetent adults. It is not deficient memory: Children remember well the ambiguous messages of adults (Experiment IV). It is not implicit demands to be polite to an adult (Experiment III). It is that children think the ambiguous messages of an adult are competent (Experiment V). Mixing the authority and prestige of an adult with incompetent messages leads the child to ignore the adult's behavior as a standard for his or her own performance. These results suggest that social learning of communication skills might occur best when the child can learn what not to do by interacting with peers and what to do when interacting with adults.     

Interference with real world knowledge

Two experiments are described in which subjects studied made-up, fantasy facts about well-known persons and then were asked to verify actual facts about these persons. Reaction time to the actual facts was longer the more fantasy propositions studied about a person. Reaction time was also longer when the verification test involved a mixture of actual and fantasy facts rather than just actual facts. A mathematical version of the ACT model (Anderson, 1976) was fit to the data. It provides a satisfactory fit, better than an alternate model. However, some of the parameter values estimated for the ACT model seemed unreasonable.     

Skilled perception in Go: Deducing memory structures from inter-response times

Experts appear able to handle much larger amounts of specialized information than nonexperts, and handle it without an apparent superior memory capacity. This finding, based on research on chess players with chess information, was replicated on Go players with Go information. Assuming this superiority occurs because the experts process chunks of information through their limited capacities rather than individual elements, the question then becomes one of defining what the chunks are and how they are related. To this end, the technique of partitioning recall and reproduction data into chunks on the basis of inter-response times (IRTs) (introduced in their work on chess by Chase and Simon, 1973) was applied to the reproduction and recall of Go patterns by a Go Master and a Go beginner. Unlike its application in chess, no single IRT was able to produce consistent, veridical chunks for either Go player. Subsequent analysis of the underlying assumptions of the technique showed it to be limited to only those patterns that can be partitioned into a linear set of chunks, not nested chunks, and to situations in which retrieval and overt recall of each chunk is completed before retrieval of the next chunk. In a supplementary task, the Master Go player indicated that the Go patterns were not seen as linear chunks nor as strictly nested hierarchies, but rather as overlapping clusters. IRTs were found to be correlated with this structure, but were not reliable enough to reflect its details.     

Gradients of attraction as a function of the fit between social setting and stimulus person characteristics: Studies of the differentiation of attitude

Two experiments compared three alternative hypotheses concerning differences in attraction to a person across interaction settings: A compartmentalization hypothesis assumes that a person's (A's) intimate and nonintimate characteristics only affect attraction to him in intimate and nonintimate interactions, respectively, and that there is no generalization of attraction across levels of intimacy. An intimacy dominance hypothesis assumes that a person's intimacy-related characteristics determine attraction to him at all levels of interaction. Finally, an intimacy threshold hypothesis assumes that a person's intimacy-related characteristics become increasingly relevant to attraction as the intimacy of interaction increases, but that these characteristics need not influence attraction at nonintimate levels of interaction. Experiment 1 supported the compartmentalization hypothesis. Attraction to a formal teacher decreased as the intimacy of the anticipated setting increased, while attraction to an informal teacher increased with increasing setting intimacy. In Experiment 2, agreement on intimate topics promoted liking for a peer while no effect was found for agreement on superficial topics. This effect only emerged for intimate interaction settings, supporting the intimacy threshold hypothesis. High positive correlations between distance preference and attraction were obtained in Experiment 1, while analogous data obtained in Experiment 2 had less clear implications.