Biomedical subjects

Timothy C Rickard

Publications and source records attributed to Timothy C Rickard.

10 recordsLinked to original sources

PubMed2006

Does working memory load lead to greater impulsivity? Commentary on Hinson, Jameson, and Whitney (2003).

Previous research by J. M. Hinson, T. L. Jameson, and P. Whitney (2003) demonstrated that a secondary task in a delayed discounting paradigm increased subjects' preference for the immediate reward. J. M. Hinson et al. interpreted their findings as evidence that working memory load results in greater impulsivity. The present authors conducted a reanalysis of the data from J. M. Hinson et al.'s Experiment 1 at the individual-subject level. Difference scores were calculated by subtracting the digit memory load condition from the control condition for k (discounting parameter) and a measure of "erroneous" responses. The results indicated that the secondary task increased random responding, which in turn can account for the increased mean estimates of k. Thus, the data do not support the claim that cognitive load affects impulsivity per se.

Decision Making↗

PubMed2006

Cued recall from image and sentence memory: a shift from episodic to identical elements representation.

The applicability of the identical elements (IE) model of arithmetic fact retrieval (T. C. Rickard, A. F. Healy, & L. E. Bourne, 1994) to cued recall from episodic (image and sentence) memory was explored in 3 transfer experiments. In agreement with results from arithmetic, speedup following even minimal practice recalling a missing word from an episodically bound word triplet did not transfer positively to other cued recall items involving the same triplet. The shape of the learning curve further supported a shift from episode-based to IE-based recall, extending some models of skill learning to cued recall practice. In contrast with previous findings, these results indicate that a form of representation that is independent of the original episodic memory underlies cued-recall performance following minimal practice.

Cues↗

PubMed2006

Transverse patterning and human amnesia.

The transverse patterning (TP) task (A+ B-, B+ C-, C+ A-) has played a central role in testing the hypothesis that medial-temporal (and, in particular, hippocampal) brain damage selectively impairs learning on at least some classes of configural (i.e., nonlinear) learning tasks. Results in the animal and human literature generally support that hypothesis. Reed and Squire [Impaired transverse patterning in human amnesia is a special case of impaired memory for two-choice discrimination tasks. Behavioral Neuroscience, 113, 3-9, 1999], however, advanced an alternative account in which impaired TP performance in amnesia reflects a generic scaling artifact arising from the greater difficulty of the TP task compared to the elemental (i.e., linear) control task that is typically used. We begin with a critique of Reed and Squire, countering their conceptual arguments and showing that their results, when analyzed appropriately, support the configural deficit hypothesis. We then report results from eight new amnesic patients and controls on an improved version of the TP task. Despite substantial practice, accuracy of patients with bilateral hippocampal damage due to anoxia reached and maintained an asymptote of only 54% correct, well below the maximum accuracy obtainable (67%) in the absence of configural learning. A patient with selective bilateral damage to the anterior thalamic nuclei exhibited a TP accuracy asymptote that was near 67%, a pattern of two out of three correct consecutive trials, and a pattern of nearly always answering correctly for two of the three TP item pairs. These results are consistent with a set of unique and parameter-free predictions of the configural deficit hypothesis.

Aged↗

PubMed2006

Verification of multiplication facts: an investigation using retrospective protocols.

Retrospective verbal protocols collected throughout participants' performance of a multiplication verification task (e.g., "7 x 3 = 28, true or false?") documented a number of different strategies and changes in strategy use across different problem categories used for this common experimental task. Correct answer retrieval and comparison to the candidate answer was the modal but not the only strategy reported. Experiment 1 results supported the use of a calculation algorithm on some trials and the use of the difference between the candidate and correct answers (i.e., split) on others. Experiment 2 clearly demonstrated that participants sometimes bypassed retrieval by relying on the split information. Implications for mental arithmetic theories and the general efficacy of retrospective protocols are discussed.

Algorithms↗

PubMed2005

A revised identical elements model of arithmetic fact representation.

The identical elements model of arithmetic fact representation (T. C. Rickard, A. F. Healy, & L. E. Bourne, 1994) states that, for each triplet of numbers (e.g., 4, 7, 28) that are related by complementary multiplication and division problems, there are 3 independent fact representations in memory: (4, 7, x) --> 28; (28/7) --> 4; and (28/4) --> 7. In this article, the author reviews the evidence for this model, considers alternative accounts, and proposes a simple and empirically motivated revision to the model that (a) accommodates conflicting results, (b) provides a novel account of the ties effect, and (c) makes new and nonintuitive predictions for the factoring operation (e.g., factoring of 28 into 4 and 7). The author reports 3 experiments designed to test these predictions and discusses implications for arithmetic instruction.

Cognition↗

PubMed2005

In search of cross-talk facilitation in a dual-cued recall task.

Despite earlier evidence that the presence of 2 redundant cues can facilitate activation of a common response, T. C. Rickard and D. Bajic (2004) found no dual-cue facilitation in the case of cued recall, provided that each cue-response association was learned independently. In this study the authors investigated the generality of their results using a dual-task cross-talk design. There was no evidence of dual-cue facilitation for compatible cue trials in the case of associative independence. Race models as well as at least some limited capacity parallel retrieval accounts can be eliminated by these and related results. It appears instead that a preretrieval stage performance bottleneck precludes cued recall through more than 1 independently represented cue-response association at a time.

Adolescent↗

PubMed2004

Memory retrieval given two independent cues: cue selection or parallel access?

A basic but unresolved issue in the study of memory retrieval is whether multiple independent cues can be used concurrently (i.e., in parallel) to recall a single, common response. A number of empirical results, as well as potentially applicable theories, suggest that retrieval can proceed in parallel, though set forth a model that denies that possibility. In this paper, five quantitative models are developed to test broad candidate principles. In multiple experiments, subjects were trained to retrieve a vocal digit response for each member of a set of letter or color cues. In subsequent test and transfer phases, single cue trials were randomly mixed with dual cue trials on which the two cues always required the same response. For the first few repetitions of each new set of dual cue items, there was no evidence of parallel retrieval over any part of the RT distribution. After more repetitions, dual cue trials were performed faster than single cue trials, but only under conditions that were favorable to development of a "chunked" dual cue representation. These results indicate that associative independence is an important modulating variable that must be heeded in any general model of attention and memory retrieval. Further, the results are most consistent with a model that places the performance bottleneck prior to the retrieval stage of processing.

Choice Behavior↗

PubMed2004

Strategy execution in cognitive skill learning: an item-level test of candidate models.

This article investigates the transition to memory-based performance that commonly occurs with practice on tasks that initially require use of a multistep algorithm. In an alphabet arithmetic task, item response times exhibited pronounced step-function decreases after moderate practice that were uniquely predicted by T. C. Rickard's (1997) component power laws model. The results challenge parallel strategy execution models as developed to date and they demonstrate that the shift to retrieval is an item-specific, as opposed to task-general, learning phenomenon. The results also call into question the entire class of smooth speed-up functions as global empirical learning laws. It is shown that overlaying of averaged item fits on averaged data can provide a sensitive test for model sufficiency. Strategy probes agreed with strategy inferences that were based on step-function speed-up patterns, supporting the validity of the probing technique.

Cognition↗

PubMed2003

Practice effects on two memory retrievals from a single cue.

The effects of practice on 2 retrievals from a single cue were investigated. In Experiment 1, participants were given extended single-task practice and were then tested on a dual memory retrieval task. Perfomance was consistent with a sequential retrieval model proposed by T. C. Rickard and H. Pashler (2003). In Experiment 2, participants practiced both single- and dual-retrieval tasks extensively. Initially, data from all participants indicated sequential retrieval. However, participants who grouped the 2 response outputs were eventually able to perform the dual task with a latency that approached the prediction of a parallel race model. Models that assume a transition from sequential to parallel retrieval with practice, along with other models that assume an immutable retrieval bottleneck at all practice levels, are considered.

Cues↗

PubMed2003

Automatic mediation or absence of mediation? Commentary on Crutcher and Ericsson (2000).

R. J. Crutcher and K. A. Ericsson (2000; see record 2000-05419-014) showed that subjects stopped reporting mnemonic mediation in a recall task after sufficient practice. They concluded that subjects continued to use the mediator indefinitely but that its execution eventually became automatic and no longer required access to working memory. Their article thus supports the more general hypothesis that multistep cognition can take place without awareness. In this article the authors evaluate that conclusion on both conceptual and empirical grounds and report results of a new experiment that indicate that a qualitative shift to direct, unmediated recall can occur for at least some tasks.

Attention↗