Mental multiplication: Nothing but the facts?

Current models of adult arithmetic performance assume that representation includes only facts and procedures. However, other kinds of representations such as an analog scale or sets of number multiples might be useful in a variety of multiplication-related tasks. Introducing the practice transfer paradigm, we demonstrate that associations between distinct representational structures can be detected via cross-task transfer, provided that initial performance is retrieval based. Results support the predictions of the integrated-structures model of multiplication knowledge. Implications for well-established item differences such as the problem-size effect are addressed, and the question of how integration occurs is considered.     

The role of orthographic and phonotactic rules in perceiving letter patterns.

Three experiments examined the role of orthographic and phonotactic rules in the tachistoscopic recognition of letter strings. Experiment 1 showed that the presence of a vowel or multiletter spelling patterns facilitates perceptual accuracy. To account for these results a model was proposed in which an input string is first parsed into syllablelike units, which are then recorded into speech. It was demonstrated that the perceptual accuracy for a string is correlated with the number of recoding steps needed to convert that string into speech. Experiment 2 further demonstrated that this recoding process can predict perceptibility differences among strings with varying numbers of phonotactic violations, and Experiment 3 assessed some of the specific assumptions of the recoding process.     

The stimulus suffix effect as a memory coding phenomenon

Two short-term memory experiments examined the nature of the stimulus suffix effect on auditory linguistic and nonlinguistic stimulus lists. In Experiment 1, where subjects recalled eight-item digit lists, it was found that a silently articulated digit suffix had the same effect on recall for the last list item as a spoken digit suffix. In Experiment 2, subjects recalled lists of sounds made by inanimate objects either by listing the names of the objects or by ordering a set of drawings of the objects. Auditory suffixes, either another object sound or the spoken name of an object, produced a suffix effect under both recall conditions, but a visually presented picture also produced a suffix effect when subjects recalled using pictures. The results were most adequately explained by a levels-of-processing memory coding hypothesis.     

Solving anagrams: Category priming and the differential availability of category solutions

An experiment was performed to test the hypothesis that the effect of category name priming on anagram solving varies with the strength of the relationship between the solution word and the priming category. Subjects solved anagrams of taxonomic category instances under primed or unprimed conditions. In the primed condition, the name of the taxonomic category from which the solution word was chosen was provided on each trial. Priming was shown to facilitate anagram solution and the extent of this facilitation was directly related to the instance dominance of the solution word in the priming category. The results were discussed in terms of current models of semantic memory.     

Knowledge Organization and the Acquisition of Procedural Expertise

The influence of the organization of a declarative knowledge base on the development and application of proceduralized knowledge was investigated in a complex troubleshooting domain. Domain explanations were generated in either a depth-first or breadth-first manner for different groups of subjects who were also given experience learning to troubleshoot in the domain. Although the two explanatory structures led to similar training performance, the two groups differed significantly in their overall level of performance in subsequent troubleshooting problems. Examination of objective measures of troubleshooting performance and think-aloud protocols indicated that breadth-first declarative knowledge representation fosters the use of mental models during problem-solving in training. It also facilitates proceduralization of that knowledge into fast and accurate methods for localizing faults.     

The direct measurement of hypothesis-sampling strategies

The concept-identification (CI) literature supports a hypothesis-sampling theory. Hypotheses based on attributes, sample sizes greater than one, and nonreplacement of eliminated hypotheses all occur. An experimental procedure was developed to measure hypothesis-sampling directly where the subject is allowed to select attributes that he wishes to see, then randomly selected values on the selected attributes are presented.Generally, the average sample size before the trial of the last error (TLE) does not change but does change after TLE. The probabilities of eliminating inconsistent hypotheses and keeping consistent hypotheses increase over problems. The proportion of eliminated attributes which are resampled decreases over problems. Individual subjects are extremely varied in sample size, efficiency measures, and resampling tendencies. The rate of solution, TLE, is related to the efficiency and resampling measures but not to the sample size.     

Effects of stimulus and contextual information on the lexical decision process

Two experiments were conducted to investigate context effects on the lexical decision process. In both experiments, observers classified letter strings as words or nonwords following the presentation of context in the form of an incomplete sentence. In Experiment 1, the predictability of congruous word stimuli and their frequency of occurrence in printed English were varied. These two factors had independent and additive effects on decision latencies. Stimulus quality, word frequency, and semantic congruity (i.e., congruous vs. incongruous) between the context and the stimulus were varied in Experiment 2. The effects of semantic congruity and word frequency on decision latencies combined additively, as did the effects of semantic congruity and stimulus quality. Two complementary mechanisms were proposed within the framework of a modified version of Becker’s verification model to account for the differential effects of single-word and sentence context priming on the lexical decision process.