Long-term memory in pigeons: I. The role of discrimination problem difficulty assessed by reacquisition measures II. The role of stimulus modality assessed by generalization slope

Pigeons learned either an easy or a difficult line angle discrimination (Experiment 1) or wavelength discrimination (Experiment 2), and then they were given a reacquisition test of retention after delays of 1 min, 1 day, or 1 week. Both percentage of responses to the S+ in the initial 10-trial block and number of blocks to criterion showed a progressive memory loss which was greater for the difficult problem. These results extend recent findings by using a free operant rather than a discrete trial task and by varying problem difficulty by altering the dimensional separation between training stimuli. In Experiment 3, pigeons were given variable interval training with either a wavelength or a line angle stimulus, and then they were tested for generalization in extinction after delays of 1 min, 1 day, and 1 week. With both dimensions, the relative gradients became progressively flatter with increasing delay intervals. This replicates earlier findings and extends them to the line angle dimension. The evidence of substantial forgetting in the first 24 h in all three experiments suggests that operant free-response procedures are more sensitive to forgetting effects than are discrete trial tasks.     

Yale Children's Inventory (YCI): An instrument to assess children with attentional deficits and learning disabilities I. Scale development and psychometric properties

The Yale Children's Inventory (YCI), a parent based rating scale, and the scales derived from it have been developed to identify and measure multiple dimensions of learning disabilities with particular emphasis on attentional deficits. Scale construction was based on factor analytic procedures. Measures of internal consistency, test retest reliability, and coefficients of congruence support the reliability and stability of the 11 scales. A discriminant function classified normal and learning disabled children with a relatively high rate of accuracy. The relationship and content of the three relevant YCI scales were compared to the DSM-III diagnostic categories for ADD. As operationalized, DSM-III criteria for hyperactivity formed a cohesive factor, while criteria for attention and impulsivity were not distinguishable from each other since they loaded together on a single factor. In contrast, the equivalent YCI scales for attention, impulsivity, and hyperactivity were found to be distinct.     

The convergence of Kuhn and cognitive psychology

Although psychology has been criticized for adhering to outmoded conceptions of knowledge (e.g. logical positivism), the assertion is made that at least one branch of psychology, namely cognitive psychology, is in the position to corroborate and extend contemporary philosophy of science. Kuhn's “learned perception of similarity” and the related notion of exemplar, which serve to exemplify more adequate conceptions of knowledge within the philosophy of science, are shown to converge with cognitive psychology's schema theory. In this way, the schema theory's empirical offspring provide a validation mechanism for Kuhn's notions and thus provide a richer understanding of the scientific enterprise. This convergence is seen as instantiating an epistemological trend towards understanding of limitations and validity of scientific evidence through an understanding of the limitations and validity of the scientist.     

Trait vs. nontrait conceptualizations of intrinsic/extrinsic motivational orientation

The present study questioned whether intrinsic vs. extrinsic motivation should be conceptualized as a trait among elementary school students. Previous instruments employing question formats that pit an intrinsic orientation against an extrinsic orientation typically result in normal distributions around the midpoint of the scale. Such a pattern could only result from a majority of children endorsing both intrinsic and extrinsic items. In the present study we investigated the hypothesis that such children may be intrinsically motivated in some school subjects but extrinsically motivated in others. Questions designed to assess motivational orientation in each of four academic subjects (math, social studies, English, and science) revealed three types of students: (a) those that were intrinsic in some subjects but extrinsic in others, (b) those that were intrinsic in all school subjects, and (c) those that were extrinsic in all school subjects. It was concluded that for the first group, motivational orientation does not function as a trait, but rather is specific to the academic content. However, for the second and third groups, motivational orientation does appear to be trait-like since children consistently report the same orientation across academic subjects. A similar analysis was applied to consistency vs. change over time where three groups were also identified. Discussion focused on the larger issues involving trait- vs. situation-specific approaches.     

A simulation laboratory for statistics

In this paper, we describe a general purpose data simulator, Datasim, which is useful for anyone conducting computer-based laboratory assignments in statistics. Simulations illustrating sampling distributions, the central limit theorem, Type I and Type II decision errors, the power of a test, the effects of violating assumptions, and the distinction between orthogonal and non-orthogonal contrasts are discussed. Simulations illustrating other statistical concepts—partial correlation, regression to the mean, heteroscedasticity, the partitioning of error terms in splitplot designs, and so on—can be developed easily. Simulations can be assigned as laboratory exercises, or the instructor can execute the simulations during class, integrate the results into an ongoing lecture, and use the results to initiate class discussion of the relevant statistical concepts.     

Characteristics of Adult Caretakers of Children and Youth Served by an Urban Child Welfare Agency

The child welfare system of the early 1990s was marked by the proliferation of home-based services. Research on the effectiveness of various home-based interventions indicates results have been equivocal. The need to make explicit the specific characteristics of the adults and children targeted for home-based services, particularly families from diverse cultural backgrounds, has been identified as a critically needed contribution to the literature. In this study, the characteristics and service utilization experiences of adults and families served in an urban, home-based, child welfare program was examined. The results are discussed in relation to findings on the characteristics and experiences of adults and families served in other settings. Implications for future research and service delivery are discussed.     

Spectral restoration of speech: Intelligibility is increased by inserting noise in spectral gaps

In order to function effectively as a means of communication, speech must be intelligible under the noisy conditions encountered in everyday life. Two types of perceptual synthesis have been reported that can reduce or cancel the effects of masking by extraneous sounds: Phonemic restoration can enhance intelligibility when segments are replaced or masked by noise, and contralateral induction can prevent mislateralization by effectively restoring speech masked at one ear when it is heard in the other. The present study reports a third type of perceptual synthesis induced by noise: enhancement of intelligibility produced by adding noise to spectral gaps. In most of the experiments, the speech stimuli consisted of two widely separated narrow bands of speech (center frequencies of 370 and 6000 Hz, each band having high-pass and low-pass slopes of 115 dB/octave meeting at the center frequency). These very narrow bands effectively reduced the available information to frequency-limited patterns of amplitude fluctuation lacking information concerning formant structure and frequency transitions. When stochastic noise was introduced into the gap separating the two speech bands, intelligibility increased for “everyday” sentences, for sentences that varied in the transitional probability of keywords, and for monosyllabic word lists. Effects produced by systematically varying noise amplitude and noise bandwidth are reported, and the implications of some of the novel effects observed are discussed.     

Why It Can't Happen to Me: The Base Rate Matters,But Overestimating Skill Leads to Underestimating Risk1

Undergraduates (N = 330) estimated their risk for aversive events (e.g., motor vehicle accident), in which we varied personal control (e.g., driver = self or other) and bogus base rates (high vs. low). Base rate data influenced risk estimates, but people underestimated their risk if they were the agent (e.g., the driver) rather than if another person was the agent. Justifications for estimates suggested that the base rate was perceived to be the risk for the average person. Most people then adjusted their estimates for a negative outcome downward because they believed that they were better than average on a skill (e.g., driving skill) that was perceived to be causally related to the event.