Fitting the psychometric function

A constrained generalized maximum likelihood routine for fitting psychometric functions is proposed, which determines optimum values for the complete parameter set--that is, threshold and slope--as well as for guessing and lapsing probability. The constraints are realized by Bayesian prior distributions for each of these parameters. The fit itself results from maximizing the posterior distribution of the parameter values by a multidimensional simplex method. We present results from extensive Monte Carlo simulations by which we can approximate bias and variability of the estimated parameters of simulated psychometric functions. Furthermore, we have tested the routine with data gathered in real sessions of psychophysical experimenting.     

Sex, shame and the transcendent function: the function of fantasy in self development

This paper explores a developmental approach to the sense of self-agency and to its influence on conscious and unconscious fantasy. I suggest that the emerging sense of self-agency offers an over-arching framework for our understanding of the nature and function of fantasy. In this context, intrusive and compulsive sexual fantasies which a person experiences as perverted and shameful, can be seen to serve differing psychic purposes, depending on the level of self-agency which is predominant. The fantasies can serve both as warning signals of the dangers of relationship and as opportunities for the mind to reflect on its own processes. Differing psychodynamic theories of fantasy are examined in terms of the developmental sense of self-agency that they represent.     

Statistical analyses of the resilience function

The extent to which distracting information influences decisions can be informative about the nature of the underlying cognitive and perceptual processes. In a recent paper, a response time-based measure for quantifying the degree of interference (or facilitation) from distracting information termed resilience was introduced. Despite using a statistical measure, the analysis was limited to qualitative comparisons between different model predictions. In this paper, we demonstrate how statistical procedures from workload capacity analysis can be applied to the new resilience functions. In particular, we present an approach to null-hypothesis testing of resilience functions and a method based on functional principal components analysis for analyzing differences in the functional form of the resilience functions across participants and conditions.     

Further examinations of the category-recall function

Subjects were assigned to use either three or six categories and were given either 5 or 10 trials in a word-sorting task. Subsequent to sorting, they recalled as many words as they could. A measure of sorting consistency showed that the six-category sort was a more difficult task than was the three-category sort. Number of categories did not have a significant effect on recall performance regardless of whether 5 or 10 sorting trials were used. A correlational analysis raised questions about the relationship of the sorting tasks to recall performance and clustering.     

Assessing the causal structure of function

Theories typically emphasize affordances or intentions as the primary determinant of an object's perceived function. The HIPE theory assumes that people integrate both into causal models that produce functional attributions. In these models, an object's physical structure and an agent's action specify an affordance jointly, constituting the immediate causes of a perceived function. The object's design history and an agent's goal in using it constitute distant causes. When specified fully, the immediate causes are sufficient for determining the perceived function--distant causes have no effect (the causal proximity principle). When the immediate causes are ambiguous or unknown, distant causes produce inferences about the immediate causes, thereby affecting functional attributions indirectly (the causal updating principle). Seven experiments supported HIPE's predictions.     

Trauma and the symbolic function of the mind

The relationship between trauma and the symbolic function of the mind is discussed in three parts. First, a short outline is given of the long‐lasting split within the field of trauma: it consists in a dichotomy between the symbolic and anti‐symbolic reading of the traumatic experience – as I have called it in a previous paper. In the second part, it is maintained that the work of Ferenczi represents an attempt at overcoming this split. In the third and last part, the notion of symbolic adaptation is introduced. The process of adaptation has to ensure the survival of the individual along lines capable to foster the hope that the lost equilibrium between the individual and his environment will one day be restored. This function is performed by symbols: by linking together the lost satisfaction and the hoped‐for wish‐fulfillment, by creating bridges between past and future, symbols enable us to adjust to the new environment without renouncing hope. Symbols are mediators between the pleasure principle and the reality principle. When a person is struck by trauma it is precisely this unifying function which is broken. A typical consequence of this situation is described by Ferenczi as a rupture between feeling and intelligence.     

On the shape of the probability weighting function

Empirical studies have shown that decision makers do not usually treat probabilities linearly. Instead, people tend to overweight small probabilities and underweight large probabilities. One way to model such distortions in decision making under risk is through a probability weighting function. We present a nonparametric estimation procedure for assessing the probability weighting function and value function at the level of the individual subject. The evidence in the domain of gains supports a two-parameter weighting function, where each parameter is given a psychological interpretation: one parameter measures how the decision maker discriminates probabilities, and the other parameter measures how attractive the decision maker views gambling. These findings are consistent with a growing body of empirical and theoretical work attempting to establish a psychological rationale for the probability weighting function.     

Studies in the learning function

From Thurstone's theoretical learning curve, a solution for the difficulty of the problem and the learning constant of the subject has been developed. The curve is an equilateral hyperbola. Therefore the semi-major axis represents the learning situation in one constant. The vertex of the curve is a point where all of the animals are equated, since they are all making errors at the rate of one error per trial.A grant-in-aid from the National Research Council has made the present analysis possible. We wish to express our appreciation, for the aid and encouragement, of Professor Rufus Crane of the mathematics department, Ohio Wesleyan University and of Professor L. L. Thurstone, University of Chicago.     

Studies in the learning function

The error function of the theoretical learning curve developed by Thurstone has been fitted to maze data from rats that have been subjected to cerebral cortical insult. There is a high degree of relationship between the number of errors necessary to complete learning as predicted from the curve and the experimental measure of learning, total-errors-minus-errors-first-trial. The procedure provides a method of analysis for individual learning records and it may be used to shorten the training period. The goodness of fit indicates that the underlying logic of the learning curve is plausible.A grant-in-aid from the National Research Council has made the present analysis possible. We are indebted to Professor L. L. Thurstone for aid and encouragement.     

Personality and the slope of loudness function

The slope of the loudness function in direct magnitude estimation was studied at two frequencies in two groups of naive subjects. In the first group a limited scale was used and in the second group, an open ended scale. In all conditions the slope of the loudness function was found to be significantly positively correlated with test anxiety scores.