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Lynch’s (1960) description of the importance of districts for spatial memory was used as a basis for looking at the contributions of semantic meaning and physical structure to learning configural spatial knowledge about an unfamiliar virtual environment. According to Lynch, meaningful grouping, not just geometric structure should facilitate spatial learning, perhaps also assisted by structure. In a virtual environment consisting of four rooms/quadrants, both the presence or absence of walls and the semantic organization of the landmark objects (grouped versus distributed category members) were factorially combined. Both object locations and navigation paths were randomly determined. Angular error was reduced by the presence of walls and by the grouping of category members in rooms/quadrants, particularly when walls were present. Performance was better than chance even when object categories were distributed evenly throughout the environment and walls were not present. The theoretical and practical implications of these results were described.

Two 6-year-old male fraternal twins each received 8 weeks of morphosyntactic and phonological intervention in counterbalanced order. Progress occurred for most targets and measures, with each child making greater progress for either phonology or morphosyntax during the corresponding unitary-domain block. Gains were maintained during the subsequent alternate treatment block. Possible indirect changes in the non-treated domain were also observed in global measures. The data suggest that at least some school-aged children with concomitant difficulties in morphosyntax and phonology, perhaps those with significant constraints in each domain, can benefit from sequences of unitary-domain intervention. This study invites further research concerning many unresolved clinical issues for school-aged children with protracted development in both phonology and morphosyntax.

Rubinstein—Taybi syndrome (RTS) is a rare genetic developmental disorder that often shows associated language delay. However, literature on language development in RTS is very limited, particularly for the period of early communicative development, when standardized testing can be minimally informative. The purpose of the current study was to present a descriptive profile of the intentional communicative acts of a 4-year-old child with RTS, both to add to the literature on the syndrome, and as an example of non-standard profiling of early communication. The child was video-recorded in a natural context with familiar conversational partners. Analyses of the videotaped interactions included rate of communication, communicative functions and modes, and discourse patterns in terms of initiation and response. The child's mean rate of communication was 6 communicative acts per minute. In terms of communicative function, assertive (commenting) communicative acts were most common, followed by directive (requests) and expressive (affective) acts. Mode of communication was less advanced than communicative function; vocalizations were the most frequent mode, although linguistic skills were emerging (signs, single words). Implications for treatment are suggested for children with development delays on the threshold between prelinguistic and one-word phases of development.

Dimensional dominance was assessed by having kindergarten children make similarities judgments about geometric figures varying in form, color, and size. Children who were classified as form dominant performed better than children who were not form dominant when given a test of letter matching ability in Experiment 1 and in repeated tests of word matching ability in Experiment 2. Data from the retest in Experiment 2 supported the hypothesis that dimensional dominance progresses from color dominance to form dominance, and then to mixed responding.

Two experiments were conducted to determine whether rats will select the T-maze alternative that has been changed between exposure and test trials when the change is one of pattern as opposed to brightness. Both experiments indicate that, with adequate adaptation to the maze and test situation prior to the test trial, rats do respond to temporal change in pattern. In the second experiment it was found that the more spatially complex stimulus was selected significantly more often on Trial 1 than was the simple patterned stimulus. The results of these experiments indicate that stimulus change, whether spatially or temporally induced, will elicit approach responses.

The relation between changes in problem difficulty and performance was extended from discrimination studies to a speeded skill task. Children were given repeated trials with easy and hard puzzle blocks. An intermediate number of changes in difficulty facilitated performance more than trial-to-trial change or no change. It was suggested that an optimal amount of change may vary with the type of task considered and that further work with various difficulty sequences and tasks seems warranted.

This article examines the role of random sampling and random assignment in the interpretation of research results. Students and faculty were asked two multiple-choice questions about research methods. When questioned about the role of random sampling, 75% of all subjects correctly associated it with generality inference (generalizability). When asked about the role of random assignment, however, only 27% of all subjects correctly associated it with causal inference. The remaining subjects allocated at least some part of the role of random assignment to generalizability. We suggest that these findings reflect a bias in psychologists' training due to teaching a statistical model that stresses random sampling and generality inference. We discuss the random assignment model, which focuses on causal inference, and recommend that both models be taught in introductory methods and statistics courses.

dents (p < .06) when making confidence judgments about research findings on the basis of probability (p) values. They found that both students and faculty were more confident of p values based on a sample of 100 than on a sample of 10, indicating that a Type I1 error was also considered. The 9 levels by group (faculty-student) interaction (P X G) was also reported to be significant. In analyzing their data Rosenthal and Gaito tested the P X G and sample sizes by groups (S X G) interactions by the triple interaction (S X P X G) by assuming that SSPG = 0. Gaito (Personal communication, 1964) has suggested that it would be more parsimonious not to make this assumption. Instead, one should employ the usual fixed effects model for two correlated variables in which the P X G and S X G interactions would be tested by P X Ss within groups and S X Ss within groups, respectively. In replicating the study by Rosenthal and Gaito, a questionnaire was given to 11 CGS graduate students and nine Fh.Ds on the CGS faculty. Ss were asked to express their "degree of belief in research findings as a function of associated p levels" based on sample sizes of 100 and 10. Ss rated each of 12 p levels (ranging from .001 to 90) for each sample size on a six-point scale from "extreme confidence or belief," 5, to "complete absence of confidence or belief," 0. The results generally confirm those of Rosenchal and Gaito, although when one uses the fixed effects model to test for significance, neither the P X G nor S X G interaction was significant in the original study or in the replication. Effects due to sample size (S) and p levels (P) were significant in both studies (p < .005) and the groups effect was significant in the replication (p < ,025). In addition, the S X P interaction was significant in the replication (p < .005), indicating that differences in confidence related to sample sizes varied across p levels. Rosenchal and Gaito also reported a "cliff effect" (sharp decrease in confidence) following the .05 level. In the replication, no significant "cliff effect" was found in intervals following the .05, .O1 or any other p level.