Output and retrieval interference in the missing-number task

Three experiments are reported that represent a reexamination of the missing-number method (Buschke, 1963b) of estimating short-term memory span. The missing-number task involved presenting a random sequence of all but one of the numbers of a known reference set and asking subjects to identify the missing number. Experiment 1 introduced a modified missing-number task that included two missing items and two choices made by the subject. With a large decline in performance for the second choice relative to the first, it is possible that only the second choice was subject to output or retrieval interference. An alternative explanation is that subjects output the number with the weakest memory representation as their first response. By postcuing subjects to report their two choices in a forward or backward sequence, Experiment 2 provided evidence against the importance of output interference and support either for the importance of retrieval interference or for the "weakest-first" hypothesis. However, with a paradigm that replaced only correctly identified missing numbers, a prediction that subjects would select the number with the weakest memory representation as their first response was not confirmed in Experiment 3. Instead, retrieval interference was implicated to explain the first-choice superiority found in Experiments 1 and 3. The results were interpreted in terms of the TODAM model of Murdock (1982, 1987, in press).     

Associative and serial-order information: Different modes of operation?

Two versions of a distributed-memory model, one for associative information and one for serial-order information, leave open the question of whether there are two different modes of operation or only one. An analysis of these two versions showed that differential predictions emerge when one considers the role of item information. To test these predictions, a standard item-recognition task (Sternberg, 1966) was embedded in a paired-associate probe-recognition task, a serial-order probe-recognition task, or both. The item-recognition serial-position curves were quite different in the paired-associate and the serial-order conditions, and followed the paired-associate condition when the two were combined. In general, the results were consistent with the predictions of the distributed-memory models, and supported the idea of different modes of operation rather than a single common mode of operation.     

Developing TODAM: Three models for serial-order information

TODAM2, a theory of distributed associative memory, shows how item and associative information can be considered special cases of serial-order information. Consequently, it is important to get the right model for serial-order information. Here, we analyze and compare three distributed-memory models for serial-order information that use TODAM’s convolution-correlation formalism. These models are the chaining model, the chunking model, and a new model, the power-set model. The chaining model associates each item with its predecessor; the chunking model uses multiple convolutions andn-grams to form chunks; and the power-set model interassociates all items in a set in a particular way to form a chunk. The models are compared in terms of their performance on seven basic tests of serial-order information—namely, serial recall, backward recall, recall of missing items, sequential probe tests, positional probe tests, serial-to-paired-associate transfer, and item recognition. The strengths and weaknesses of each model are discussed.     

Processing of threat-related information in rape victims

We investigated selective processing of threat information in persons with posttraumatic stress disorder (PTSD) by using a modified Stroop procedure. Subjects were 15 rape victims with PTSD, 13 rape victims without the disorder, and 16 nontraumatized control subjects. They were asked to name the color of four types of words: specific threat (rape-related) words, general threat (related to physical harm and death) words, neutral words, and nonwords. Rape victims with PTSD evidenced a longer response latency for color naming of rape-related words than for other target-word types. Response latencies of non-PTSD victims and nonvictim control subjects did not differ across word types. Possible mechanisms underlying the selective processing of threat material are considered, and clinical implications are discussed.     

Storage and retrieval of serial-order information

In this paper I will first review some seminal work by Conrad on the storage and retrieval of serial-order information which is still very relevant today. Then I will discuss the TODAM (theory of distributed associative memory) approach to serial-order effects. I will compare the three TODAM serial-order models (the chaining model, the chunking model and the power-set model; Murdock, 1995) but concentrate on the power set model. Its original problems can be solved, but a revised and augmented version has some new problems. This paper is more of a progress report than a finished product, so the reader should be prepared to follow the twists and turns of the argument.     

A Comparison of Results and Acceptability of Functional Behavioral Assessment Procedures with a Group of Middle School Students with Emotional/Behavioral Disorders (E/BD)

There is currently controversy over the validity and applicability of functional behavioral assessment (FBA) procedures with students with emotional/behavioral disorders (E/BD). A set of FBA procedures, including teacher and student interviews and direct classroom observations, were carried out with eight students with disabilities (7 classified E/BD, one classified LD). Results indicated that when all three methods (teacher/student interviews, classroom observations) yielded a ranking for a function they agreed 64% of those occasions. For those situations in which there was overall disagreement there was agreement between teacher interview and classroom observations most of the time. Social validity data indicated that both students and teachers felt that the assessment procedures were a useful and productive process.     

Differentiation of Self, Stress, and Emotional Support as Predictors of Psychological Distress

We explored the relations among stress, emotional support, and differentiation of self from the family of origin as predictors of psychological distress in a sample of 200 college students. First, we investigated the discrepant findings of Murdock and Gore (Contemp Fam Ther 23: 319–335, 2004) and Skowron et al. (J Couns Dev 82: 69–78, 2004) regarding the relationships among stress, differentiation, and symptoms (a question of mediation vs. moderation). Second, we examined the role of emotional support in concert with stress and differentiation. When both stressful events and perceived stress were measured, differentiation of self was found to be a significant partial mediator of their effects on psychological distress. Emotional support was also found to partially mediate the relationship between differentiation of self and psychological distress. Differentiation of self partially mediated the relationship between actual and perceived stress, and perceived stress partially mediated the relationship between differentiation of self and psychological distress.     

Decision-making models of remember-know judgments: comment on Rotello, Macmillan, and Reeder (2004)

The sum-difference theory of remembering and knowing (STREAK) provides a sophisticated account of many interactions in the remember-know (R-K) area (C. M. Rotello, N. A. Macmillan, & J. A. Reeder, 2004). It assumes 2 orthogonal strength dimensions and oblique criterion planes. Another dual-process model (J. T. Wixted & V. Stretch, 2004) with one decision axis has also been applied to R-K judgments with considerable success and provides new insights into the processes involved. An analysis of the 4 major R-K interactions can also be explained by a simpler one-dimensional signal detection theory (J. C. Dunn, 2004a). However these models do not make contact with standard work on recognition memory, so their scope is limited. To bridge this gap, a global-matching model (a theory of distributed associative memory [TODAM]) for R-K judgments is proposed. This model can produce good fits to the data, and there are established experimental manipulations with which to test it. It provides further support for the idea that R judgments are based on associative information, whereas K judgments are based on item information.