Dynamic structural systems under indirect observation: identifiability and estimation aspects from a system theoretic perspective

In this—partly—expository paper the parameter identifiability and estimation of a general dynamic structural model under indirect observation will be considered from a system theoretic perspective. The general dynamic model covers (dynamic) factor analytic models, (dynamic) MIMIC models and Jöreskog's linear structural model as special cases. Its reduced form is—under a slightly different specification—known in system theory and econometrics as the stochastic, stationary version of the state-space model. By using concepts and methods from system theory, such as the observability and controllability concept, the (steady-state) Kalman filter and a general nonlinear ML_estimation procedure known as prediction-error estimation the general dynamic model will be identified. It will be shown that Jöreskog's LISREL-procedure is a special case of the prediction-error estimation procedure.     

Concurrent schedules: Transient-state changeover behaviour

Ten pigeons responded in a two-alternative continuous-choice situation. Rein-forcers were programmed by a single variable-interval 30-sec schedule. The proportion of reinforcers assigned to one alternative was either 0.67 or 0.50 in different conditions. The changes in local changeover rates following changes of conditions were adequately described by an exponential function. This result can be explained by a model of changeover behaviour proposed by Myerson and Miezin (1980), if a simplifying assumption is made about reinforcement rates as controlling variables. A modification of the Myerson and Miezin model that accounts for the exponential function but does not make assumptions about reinforcement rates as controlling variables is presented.     

Phonological coding in reading of deaf children: Pseudohomophone effects in lexical decision

The purpose of this study was to find new evidence for phonological coding in written word recognition among deaf Dutch children. A lexical decision task was presented to 48 severely and profoundly deaf children aged from 6 years 8 months to 13 years 5 months, and a control group of Grade 1 hearing children matched on written word recognition. Sixteen pseudohomophones were introduced, closely matched on orthographic similarity with 16 control pseudo-words. Both hearing children and deaf children made significantly more mistakes on pseudohomophones than on control pseudo-words. Although pseudohomophony effects were smaller for deaf than for hearing participants, the findings were taken as evidence that deaf children also used phonological coding during written word recognition.     

Cross-cultural consistency of coding the strange situation

This study tested whether or not cross-cultural differences in attachment classification distributions result from systematic differences in coding practices. First, we investigated whether or not the interactive scales have been scored consistently in several different cross-cultural samples. Second, the Richters, Waters, and Vaughn (1988) functions were applied to address the question of whether or not attachment classifications were consistently based upon the same pattern of interactive behaviors. Third, cross-cultural coding differences were described from a multivariate perspective. Data sets from seven investigators in six countries were available for analysis. Analyses on this “multinational data set” revealed that except for distance interaction, the interactive scales in the two reunion episodes were scored in accordance with the original coding rules. Furthermore, a good to reasonable agreement appeared to exist between the original classifications and those computed by the functions, except for infants older than 20 months of age. The multivariate principal component analysis showed that classification groups across cultures were more alike than cultures across classification groups. Our data showed, therefore, that attachment classifications have been consistently coded across cultures.     

Evaluating a ward staff program for increasing spontaneous and varied communicative gesturing with individuals who are mentally retarded

In the present study we assessed the effect of a multifaceted program for ward staff members, which was intended to have severely/profoundly mentally retarded individuals improve their use of communicative gestures. The program consisted of instruction, verbal and visual (publicly posted) graphic feedback. There were two categories of dependent variables. The first category involved the number of gesture prompts by staff, number of unused opportunities to evoke gestures, and number of consequences given for gestures. The second category involved handicapped individuals' number of prompted gestures, number of spontaneous gestures, and number of different gestures. Results show that the program was effective with regard to all these variables. Changes in the number of spontaneous gestures were especially remarkable, as this variable had not been influenced directly. Follow-up data underline the effectiveness of the program.     

Systemic Explanations of Scientific Misconduct: Provoked by Spectacular Cases of Norm Violation?

Journal of Academic Ethics - In the past two decades, individual explanations of scientific misconduct (‘bad apples’) have increasingly given way to systemic explanations (‘bad...     

Transfer Effects in Children's Recall of Arithmetic Facts

Predictions of the Identical Elements (IE) model of arithmetic fact representation (Rickard, 2005 Rickard, T. C. 2005. A revised identical elements model of arithmetic fact representation. Journal of Experimental Psychology: Learning, Memory, and Cognition, 31: 250–257. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Rickard & Bourne, 1996 Rickard, T. C. and Bourne, L. E. 1996. Some tests of an identical elements model of basic arithmetic skills. Journal of Experimental Psychology: Learning, Memory, and Cognition, 22: 1281–1295. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) about transfer between arithmetic facts were tested in primary school children. The aim of the study was to test whether the IE model, constructed to explain adult performance, also applies to children. The IE model predicts no positive transfer when the numerical elements of a test problem do not match exactly with those of a practice problem. In two experiments, children practiced addition or multiplication problems. A large positive transfer effect was found for problems with an operand order change; improvement was just as high as for practiced problems. Smaller transfer effects were found for problems where one operand was increased with one unit and for problems with operands more different from practice problems. Analogous results were found for addition and multiplication, suggesting that storage and retrieval processes in both domains are similar in children. The findings suggest that there is a gradual decrease in transfer as the test problems become more different from practice problems, indicating that a more sophisticated model than the IE model is needed to explain transfer effects in children's recall of arithmetic facts.