Learning models for a continuum of sensory states reexamined

Dorfman and Biderman evaluated an additive-operator learning model and some special cases of this model on data from a signal-detection experiment. They found that Kac's pure error-correction model gave the poorest fit of the special models when the predictions were generated from the maximum likelihood estimates and the initial cutoffs were set at an a priori value rather than estimated. First, this paper presents tests of an asymptotic theorem by Norman, which provide strong support for Kac's model. On the final 100 trials, every subject but one gave probability matching, and the response propcrtions appropriately normed were approximately normally distributed with variance π(1 ? π). Further analyses of the Dorfman-Biderman data based upon maximum likelihood and likelihood-ratio tests suggest that Kac's model gives a relatively good, but imperfect fit to the data. Some possible explanations for the apparent contradiction between the results of these new analyses and the original findings of Dorfman and Biderman were explored. The investigations led to the proposal that there may be nonsystematic, random drifts in the decision criterion after correct responses as well as after errors. The hypothesis gives a minor modification of the conclusions from Norman's theorem for Kac's model. It gives asymptotic probability matching for every subject, but a larger asymptotic variance than π(1 ? π), which agrees with the data. The paper also presents good Monte Carlo justification for the use of maximum likelihood and likelihood-ratio tests with these additive learning models. Results from Thomas' nonparametric test of error correction are presented, which are inconclusive. Computation of Thomas' p statistic on the Monte Carlo simulations showed that it is quite variable and insensitive to small deviations from error correction.     

Relational judgments with remembered stimuli

Two experiments investigating the effect of the direction of a relational judgment on the speed of the judgment are reported. In both experiments, college students required more time to select the smaller of a pair of large animals than to select the larger. Conversely, the smaller of a pair of small animals was selected more quickly than was the larger. The magnitude of this “cross-over effect” was fully graded, increasing regularly with extremity, but the variability of the response times in each direction was unrelated to extremity. Individual animals were classified as “small” or “large” with almost perfect consistency. This pattern of results is used to evaluate several models of relational judgment; of these, the congruency model is shown to be inconsistent with these data.

     

Stimulus encoding selectivity at high degrees of paired-associate learning

Sixty-two Ss learned six CCC trigram-digit pairs by the study-test method; 21 Ss continued the PA acquisition trials to a learning criterion of one errorless trial, while 41 Ss were carded to 300% overlearning or 24 trials, whichever came first. The Ss were then shown individual letters of the trigrams, with position cues provided, and were tested for their ability to provide the digit and produce the additional letters. Digit recall was much better to initial letters than to those in the second or third positions of the trigrams; with oveflearning, digit recall improved to the initial letters but not to letters in second and third positions. Production of additional letters of the trigrams was not appreciably related to either cue position or degree of PA learning. There was some evidence ofincreased selectivity with higher degrees of PA learning.     

Aspects of the theory of comprehension, memory and attention

This paper proposed a two-stage model to capture some basic relations between attention, comprehension and memory for sentences. According to the model, the first stage of linguistic processing is carried out in short-term memory (M₁) and involves a superficial analysis of semantic and syntactic features of words. The second stage is carried out in long-term memory (M₂) and involves application of transformational rules to the analyses of M₁ so as to determine the deep or underlying relations among words and phrases. According to the theory, attention is an M₂ process: preliminary analyses by M₁ are carried out even for unattended inputs, but final analyses by M₂ are only carried out for attended inputs. The theory was shown to be consistent with established facts concerning memory, attention and comprehension, and additional support for the theory was obtained in a series of dichotic listening experiments.     

SDT analysis of binary decisions and sensory intensity ratings to noxious thermal stimuli

During three sessions, each of 24 Ss responded to noxious thermal stimuli, using the following judgments: binary decision, S responded “high” or “low”; sensory intensity rating, S rated his sensory experience along a thermal intensity continuum; and concurrent report, S’s binary decision was followed by an intensity rating. The binary-decision d’ was significantly higher than the rating d′, suggesting that Ss could not maintain multiple thermal criteria in a consistent fashion. The criteria for pain obtained with single and concurrent intensity rating judgments did not differ. These results suggest that the most efficacious and valid method for the study of experimental pain is to obtain concurrent responses, and to use binary decisions to compute d’ and sensory intensity ratings to locate S’s criterion for reporting pain.     

Process thought in Tillich's eschatology

International Journal for Philosophy of Religion -