Computer simulation with DATASIM

A general purpose program is described for generating, analyzing, and graphing simulated data for experimental, multivariate, and contingency table designs. Applications include simulating actual or hypothetical research studies, conducting Monte Carlo investigations of the consequences of violating assumptions on statistical tests, generating randomized data sets for students to analyze and interpret as homework, and performing simulations demonstrating sampling theory. Data sets may be generated that have normal or nonnormal distributions, independent or correlated observations, and equal or unequal sample sizes. Data-analysis capabilities include one-way, two-way, and three-way ANOVA with any combination of independent- and correlated-groups factors, as well as simple-effects analyses, multiple pairwise comparisons, linear contrasts, and trend analyses.     

A Case-Study of the Careers Service Placement Function

A number of models of the placement function of the Careers Service are presented. Various hypotheses generated by the models are tested, using data collected from Careers Service records. Specifically, a multivariate analysis is performed to show which personal and social characteristics are associated with a higher probability of being submitted for a permanent vacancy. The implications of the analysis for the Careers Service are discussed.     

Ego development in the face of death: How being HIV positive affects movement through Erikson's adult stages of development

Erikson's epigenetic model of psychosocial development posits that each of eight stages unfolds in a particular sequence, and each becomes the primary issue of concern at specified times in the life cycle. Erikson does not address, nor could any empirical studies be located, exploring how the emergence of these eight stages might be affected by a diagnosis of terminal illness. The purpose of this study was to understand how an HIV-positive diagnosis affected movement through Erikson's stages of development. In-depth interviews were conducted with a sample of 18 HIV-positive men and women under 45 years of age. Analysis of the qualitative data revealed three findings regarding Erikson's stages: (1) The fifth stage of idenitity versus role confusion was revisted and the sense of self is redefined; (2) the three adulthood stages of intimacy versus isolation, generativity versus stagnation, and ego integrity versus depair were dealt with simulataneously and, in most cases, resolved favorably; and (3) intimacy and generativity enabled and supported the resolution of the tasks of identity and ego integrity.     

A follow-up study of cognitive bias in generalized anxiety disorder

Patients with generalized anxiety disorder (GAD) without concurrent depression (n = 11) and normal controls (n = 17) were tested twice, about 2 months apart, on a modified Stroop colour-naming task, which presented anxiety-related, depression-related and neutral words in masked and unmasked exposure conditions. GAD patients received cognitive behaviour therapy in the test-retest interval, and were also retested at follow-up, about 20 months after initial testing. GAD patients showed interference in colour-naming negative words across both masked and unmasked conditions before treatment, but not post-treatment, compared with controls. Reduced interference effects of masked threat words over time correlated with reduced ratings of anxious thoughts at post-treatment, and at follow-up, in GAD patients. Thus, the preconscious bias for threat information in GAD appears to vary over time in association with changes in anxious thoughts and worries.     

Occupational stress within a U.K. higher education institution

Occupational stress in a U.K. higher education institution was investigated during a period of considerable organizational change. All employees, including academic, support and manual staff, were invited to participate anonymously in the survey. The results, based on the Occupational Stress Indicator, showed that employees reported significantly poorer mental and physical well-being, and greater job dissatisfaction, than a normative group. The findings suggested that female employees were at greater risk from adverse effects of occupational stress. Predictors of distress and job dissatisfaction were identified. The study concluded that occupational stress is a significant problem, and that further investigation is required in other similar institutions.     

Desktop flight simulators: Simulation fidelity and pilot performance

Improvements in the computing power and visual resolution of modern desktop computing systems, as well as advances in software technology for displaying high-speed animations, have encouraged the development of relatively sophisticated real-time flight simulators for the PC and Macintosh. We review some of the factors that determine how well such programs capture the actual experience of flight. The most significant factor limiting the quality of performance in flying a simulated aircraft is the “frame rate” problem: at low altitudes and in highly detailed visual environments, as in approaching a runway threshold during landing, the computational demands of the animation may necessitate a reduction in the number of frames displayed per second on the screen. The delayed sensory feedback that results proves to be very detrimental to sustaining smooth control of the aircraft, especially during the flare to touchdown where such control is needed most. This finding parallels the well-known effects of delayed auditory feedback (Lee, 1950) and delayed visual feedback (Smith, 1962).     

Spectral redundancy: Intelligibility of sentences heard through narrow spectral slits

The intelligibility of word lists subjected to various types of spectral filtering has been studied extensively. Although words used for communication are usually present in sentences rather than lists, there has been no systematic report of the intelligibility of lexical components of narrowband sentences. In the present study, we found that surprisingly little spectral information is required to identify component words when sentences are heard through narrow spectral slits. Four hundred twenty listeners (21 groups of 20 subjects) were each presented with 100 bandpass filtered CID ( “everyday speech ”) sentences; separate groups received center frequencies of 370, 530, 750, 1100, 1500, 2100, 3000, 4200, and 6000 Hz at 70 dBA SPL. In Experiment 1, intelligibility of single 1/3-octave bands with steep filter slopes (96 dB/octave) averaged more than 95% for sentences centered at 1100, 1500, and 2100 Hz. In Experiment 2, we used the same center frequencies with extremely narrow bands (slopes of 115 dB/octave intersecting at the center frequency, resulting in a nominal bandwidth of l/20 octave). Despite the severe spectral tilt for all frequencies of this impoverished spectrum, intelligibility remained relatively high for most bands, with the greatest intelligibility (77%) at 1500 Hz. In Experiments 1 and 2, the bands centered at 370 and 6000 Hz provided little useful information when presented individually, but in each experiment they interacted synergistically when combined. The present findings demonstrate the adaptive flexibility of mechanisms used for speech perception and are discussed in the context of the LAME model of opportunistic multilevel processing.     

Some variables affecting children's compliance with instructions

Children were given instructions to perform different tasks. Compliance was studied as a function of several variables: the prevailing pattern of reinforcement for different instructions, the availability of a competing reinforced activity, and the similarity among tasks. Rate of compliance tended to decrease when the probability of reinforcement for compliance decreased, or when a competing reinforced activity was available. Differential reinforcement over the tasks did not always produce discriminative responding even under favorable conditions. Novel instructions obtained compliance at the same rate as that for frequently repeated instructions, independent of the novel instruction's past or present reinforcement history. Greater discrimination in responding was found when tasks were less similar. Results imply that sets of instructions may form a response class, with characteristics similar to those found in studies of generalized imitation.     

Speech acquisition in a nonverbal isolate child

The present study attempted to evaluate experimentally the relationship between two response classes: cooperative play and speech. One child was observed in a preschool free-play setting. Base rates of speech and play with peers indicated that the child never spoke to or played with peers during free-play periods. Base rates of teacher attention were observed to fluctuate directly with the child's isolate play. When differential attention and extinction operations were presented, removed and presented again, the frequency of cooperative play with peers increased, decreased and increased accordingly. Moderate fluctuations in verbal behavior also correlated with the presence and absence of the differential attention and extinction operations, even though the operations were applied only to cooperative play. The results suggest that some nonverbal isolate children may begin producing speech when play behaviors with peers are reinforced by teachers.     

Rhyme, rime, and the onset of reading

There is recent evidence that children naturally divide syllables into the opening consonant or consonant cluster (the onset) and the rest of the syllable (the rime). This suggests an explanation for the fact that preschool children are sensitive to rhyme, but often find tasks in which they have to isolate single phonemes extremely difficult. Words which rhyme share a common rime and thus can be categorized on that speech unit. Single phonemes on the other hand may only be part of one of these speech units. This analysis leads to some clear predictions. Young children, even children not yet able to read, should manage to categorize words on the basis of a single phoneme when the phoneme coincides with the word's onset ("cat," "cup") but not when it is only part of the rime ("cat," "pit"). They should find it easier to work out that two monosyllabic words have a common vowel which is not shared by another word when all three words end with the same consonant ("lip," "hop," "tip") but the odd word has a different rime than when the three words all start with the same consonant ("cap," "can," "cot") and thus all share the same onset. The hypothesis also suggests that children should be aware of single phonemes when these coincide with the onset before they learn to read. We tested these predictions in two studies of children aged 5, 6, and 7 years. The results clearly support these predictions.