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Showing papers by "Tilburg University published in 1979"


Journal ArticleDOI
TL;DR: The purpose of the study was to investigate the time course of amplitude changes in both legs, in muscles both involved and not involved in the response, and it was concluded that the second increase might be part of a motor preparation process.
Abstract: During the fixed foreperiod (4 sec) of two reaction time experiments, using 80 subjects, Hoffman reflexes were simultaneously evoked in both legs in a pseudorandom order at 13 different measuring points. The purpose of the study was to investigate the time course of amplitude changes in both legs, in muscles both involved and not involved in the response. In Experiment 1, subjects responded after the imperative signal by a plantar flexion of either the right or left foot. Thus, reflexes were evoked via the motoneuron pool relevant for the response and via the contralateral irrelevant pool. In Experiment 2, subjects pressed a button with either the right or the left index finger. Thus, reflexes were evoked via motoneurons, irrelevant for the response. Reflex amplitudes during the foreperiod were larger than during the intertrial interval (ITI). An early increase was found at 100–200 msec after the warning signal. Thereafter, amplitudes decreased but remained larger than during the ITI. After 1,000 msec, a steady increase was found, with the largest amplitudes near the end of the foreperiod. Amplitude changes were not different for relevant and irrelevant muscles. It was concluded that the second increase might be part of a motor preparation process.

34 citations


Book ChapterDOI
01 Jan 1979
TL;DR: In this article, the authors discuss the role of convex analysis in mathematical economics, particularly in relation to the notions of optimum and equilibrium, and most equilibrium definitions in economics are closely related to the game theoretical concept of Nash-equilibrium.
Abstract: Convex analysis plays an important role in mathematical economics, particularly in relation to the notions of optimum and equilibrium. Also, most equilibrium definitions in economics are closely related to the (game theoretical) concept of Nash-equilibrium (see Debren [3]).

23 citations


Journal ArticleDOI
TL;DR: In this article, the influence of norms and sex of subjects on aggressive behavior in same sex dyads was studied experimentally and it was concluded that positions grounded on the S-R paradigm are misleading for the understanding of sex differences in aggression.
Abstract: Studied experimentally the influence of norms and sex of subjects on aggressive behaviour in same sex dyads. Two hypotheses were tested: (1) subjects will react aggressively to an unpleasant state of affairs, if they interpret it as being the result of violation of a norm on the part of another; (2) female subjects will display more aggression than male subjects under conditions of repeated provocation while male subjects will be more aggressive under conditions of infrequent or no provocation. In a 2 × 2 × 2 complete factorial design (norm violation versus norm enforcement; male versus female; low versus high reward for performance) 20 same sex pairs of students performed alternatively a sensory-motor task (victim) and a shock delivery task (aggressor). As predicted, subjects who consider other's behaviour to be a norm violation aggress more often (p <.0001). A significant interaction between sex of subject and norm violation is found in support for the second hypothesis (p <.05). It is concluded that positions grounded on the S-R paradigm are misleading for the understanding of sex differences in aggression.

17 citations


Journal ArticleDOI
Piet Verheyen1
TL;DR: In this article, the authors give an economic interpretation of results derived from mathematical replacement models and show that the moment of replacement is always determined by the equality of marginal replacement costs to the marginal costs of postponed replacement.

15 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the effect of different stimulation frequencies on the state of arousal of the subject's blink reflexes, and concluded that the amplitude of R 1 amplitude reflects the level of arousal in the subject.

13 citations


Book ChapterDOI
01 Jan 1979
TL;DR: Research in developmental neuropsychology has emphasized empirical methods and differences in methodology have probably restricted broader conceptual understanding Moreover, attention has too often been focused on isolated tests purporting to measure left-right discrimination, form perception, writing, and calculation as mentioned in this paper.
Abstract: Research in developmental neuropsychology has emphasized empirical methods and differences in methodology have probably restricted broader conceptual understanding Moreover, attention has too often been focused on isolated tests purporting to measure left-right discrimination, form perception, writing, and calculation This state of affairs has generated a plethora of studies into specific developmental disorders, but these are often based on unrepresentative cases, inadequate design, and isolated behaviors Theory development has been slow, thus preventing the conceptual integration of findings which appear unrelated or discrepant with specific hypotheses

9 citations


Journal ArticleDOI
A. van Boxtel1
TL;DR: Electro EEG alpha activity, derived from electrodes widespread over the ipsilateral and contralateral hemispheres, was tested but no relationships between alpha phase and reflex amplitudes were found.

4 citations


Journal ArticleDOI
TL;DR: An investigation into the general validity of formulae derived for the expected queue-length and the expected waiting-time inQueueing theory with balking found that they were partly an extension of the standard queueing theory and partly an indication for further theoretical investigation.
Abstract: Queueing theory becomes considerably more complicated if impatient customers fail to join the queue, so-called balking. Analytical results have been obtained for the standard queueing problem (M/M/1) with balking, i.e., formulae have been derived for the expected queue-length and the expected waiting-time. This report describes an investigation into the general validity of these formulae. Since an analytical approach to the problem has so far proved to be unfeasible, simulation was used. We tried to construct an efficient simulation model. The model was analysed using regenerative properties - a technique which provides a solution to the problem of correlated simulation observations. The results we found were partly an extension of the standard queueing theory and partly an indication for further theoretical investigation.

2 citations


Journal ArticleDOI
TL;DR: This procedure depends on the assumption that the data are missing at random and the estimates will be quite unsatisfactory when the missing variables do not correlate highly with at least one of the available variables and/or when the proportion of missing entries is large.
Abstract: XI is of order n by PI and X 2 is of order n by P2. The partitioned correlation matrix is: standardized regression coefficients into unstandardized coefficients and by computing the intercepts. Before estimating missing data by Equation 1, the correlation matrix R must be estimated. Two methods can be used: Wilks (1932) proposes substituting the corresponding column mean for each missing entry; Glasser (1964) estimates R from all available pairs of scores for each pair of variables. The estimates obtained from Equation 1 can be improved by iteration. The estimates from one iteration can be used to improve the estimate of the correlation matrix for use in a next iteration. The program, however, becomes very expensive to run when the number of iterations is large. This procedure depends on the assumption that the data are missing at random and the estimates will be quite unsatisfactory when the missing variables do not correlate highly with at least one of the available variables and/or when the proportion of missing entries is large. Description. The main program uses a set of FORTRAN IV subroutines. These routines implement the estimation procedure and all supplementary operations. The subroutine WILKS computes the correlation matrix R by Wilks' (1932) method; GLASSER computes R by Glasser's (1964) method; TRANSF draws R 1 and RII from the relevant parts of R-I; REGRES estimates the missing entries according to Equation 1; CORR computes correlations and standard deviations; XMISS generates a data presence-absence matrix; GRINV is a matrix inversion routine that was published by Kaiser and Dickman (1972). The set also includes a matrix printing and punching routine. Input. The job deck consists of the following cards. Card 1 is the alphameric title; Card 2 specifies the number of rows (N) and columns (NP) of the data matrix; Card 3 contains the choice of procedure for computing R (NR) and the number of iterations (NRUN) , and it contains an option for punching the data matrix with estimated missing entries (NPU); Card 4 is the data format card (F-type variable format); Card 5 contains the code for missing entries. The next cards contain the raw data matrix. Each row of the data matrix must begin on a new card. The use of more than one card per row is permitted. Output. The printed output includes the titling information and, for each iteration, the correlation matrix, the data matrix with estimated missing entries, and corresponding means and standard deviations. The proportion of missing entries is also reported; the program gives a warning when this proportion exceeds the limit of .20. The data matrices with estimated missing entries can be punched as desired. Restrictions. The data matrix may not have more than 200 rows and 10 columns. These limits can easily (2) (1)

1 citations


Journal ArticleDOI
TL;DR: In this article, a review and an evaluation of Lenderink and Siebrand's analytical and empirical approaches to the short run phenomena on the Dutch labour market during the period 1952-1970 are presented.
Abstract: The article has been divided into two main parts. The first consists of a review and an evaluation of Lenderink and Siebrand's analytical and empirical approaches to the short-run phenomena on the Dutch labour market during the period 1952–1970. The main implications are explicitly stated and show how the authors have integrated the relevant results of equilibrium and disequilibrium analysis. It appears that the general analytical approach of Lenderink and Siebrand certainly is very promising. From the comments in the second part it becomes clear that the authors' main empirical results should be rejected. Some new data are produced to be compared with the originally presented data. They provide the basis for emphasizing that the original analysis does not satisfy some theoretical and empirical consistency conditions. Therefore, suggestions for revision of some aspects of Lenderink and Siebrand's study are recommended.

1 citations


Journal ArticleDOI
Heije Faber1
TL;DR: In this article, the author utilizes Ian T. Ramsey's "model" construct as a vehicle to "disclose" the identity of the minister, and uses the clown to point to the minister's vulnerability, his trust, his integrity, and shows how suffering can have a special relation to the understanding of the presence of God.
Abstract: The author utilizes Ian T. Ramsey's “model” construct as a vehicle to “disclose” the identity of the minister. Thus he uses the clown to point to the minister's vulnerability, his trust, his integrity, and shows how suffering can have a special relation to the understanding of the presence of God.