Criterios del análisis de la equidad educativa en la ES: el paradigma distributivo

processing and organisation imposed on stimuli in order to meet the demands of the training task. At test, the retrieval o f episodic-processing knowledge drives both accuracy and confidence judgements. Test items that are similar to training items are processed more fluently than test items that are dissimilar to training items and the relative fluency of processing forms the basis of both accuracy and subjective confidence judgements. In contrast to the dual-knowledge account, this unitary processing approach predicts that because accuracy and confidence are driven by the same information, (1) participants will perform at chance when they say they are guessing (i.e., there will be no evidence to support the guessing criterion), and (2) there will be a correlation between accuracy and confidence (i.e., there will be no evidence to support the zero correlation criterion).

Conflicting results have been reported in five previous AGL studies that tested the guessing and zero correlation criteria using the same-letter set for training and test stimuli. Chan (1992, cited by Dienes, Altmann, Kwan, & Goode, 1995) and Dienes, Altmann, Kwan, and Goode (1995) found evidence for implicit knowledge according to both criteria. Dienes and Altmann (1997, Experiment 2) found evidence for the guessing criterion, but not the zero correlation criterion. Redington, Friend, and Chater (1996) and Whittlesea, Brooks, and Westcott (1994) found no evidence of implicit knowledge by either criteria.

Unfortunately the studies that supported the guessing and zero correlation criteria only measured the grammatical status of test strings and failed to control for

the effects of fragment knowledge (ACS) on test performance1. As suggested by much previous AGL research, there is evidence to support fully (e.g., Dienes, Broadbent & Berry; 1991; Dulany, Carlson & Dewey, 1984; Johnstone & Shanks,

1999; Perruchet, 1994; Perruchet, Gallego, & Pacteau, 1992; Perruchet & Pacteau, 1990; Redington & Chater, 1996; Servan-Schreiber & Anderson, 1990) or partially support (e.g., Knowlton & Squire, 1994, 1996; Meulemans & Van der Linden, 1997) the view that classification test performance is driven by the overlap of letter

fragments between training and test items. Indeed the results o f Experiments 1 and 2 (Chapters 3) indicate that when ACS is equated across grammatical and

ungrammatical test strings, match participants perform at chance in relation to the rules of the grammar.

Therefore, if the guessing and zero correlation criteria are measuring real effects then these effects should be stronger when assessed according to the true basis of classification decisions (i.e., ACS) than when assessed according to the

grammaticality o f test strings. The aims of Experiment 7 were to assess the

relationship between accuracy and confidence for both rule and ACS knowledge and to test the predictions of the dual knowledge (Dienes & Perner, 1998) and episodic- processing (Whittlesea & Dorken, 1997) accounts o f the relationships between accuracy and subjective confidence.

1 For example, the grammatical and ungrammatical test strings used by Dienes and Altmann (1997) differed for both anchor ACS (M = 5.71 versus 1.09), t (56) = 15.65, SE = .30, and global ACS (M = 8.83 versus 2.86), t (56) = 8.88, SE = .67.

Experiment 7

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Participants were trained and tested on the stimuli used in Experiment 5, as these strings unconfound the contributions of rule and ACS knowledge in

classification performance. On each classification trial, participants were first asked to indicate whether the test string was grammatical or ungrammatical and then asked to specify how confident they were in the accuracy o f their initial response. Confidence was rated on a scale from 50 to 100%, where 50% indicated guessing and 51-100% indicated increasing levels of confidence.

Based on the results of Experiments 1-6, it was predicted that classification performance would be at chance in relation to grammaticality, but above chance in accordance with ACS. Support for the dual-knowledge account required that

participants classify at above chance levels in the 50% confidence category (guessing criterion), with no relationship between accuracy and confidence for all responses (50-100%) (zero correlation criterion). In contrast, support for the episodic-processing account required that participants perform at chance when they used the 50%

confidence rating and that there was a relationship between confidence and accuracy across all responses (50-100%).

M ethod

Participants. 21 students at University College London performed the experiment and were each paid £5 for taking part.

Procedure. The same match task, letter strings and classification test were used as in Experiment 5, with a minor modification to the classification test. On each trial, participants were first asked to press the Y key if they believed that the string

conformed to the rules of the earlier strings or the N key if they believed that the string did not conform to the rules of the earlier training strings. They were then asked to rate how confident they were that their Y or N response was correct on a scale ranging from 50% (complete guessing) to 100% (complete certainty). They were encouraged to use any integer within this range to indicate as accurately as possible their confidence in their Y or N judgement.

Results

The mean percentages of training items across four blocks o f training on which participants made correct responses was 89%, 90%, 91%, and 93% with an overall accuracy level o f 91%. A one-way ANOVA comparing accuracy with training block (1 to 4) as a within-subject variable, indicated that there was no effect o f block, F (3, 60) = 1.51, M SE =31.81. This indicated that accuracy levels remained at

around 90% across all training blocks.

The mean percentage of items classified as grammatical for the four test item types was 70% (GH), 32% (GL), 69% (UH), and 38% (UL). The overall mean percentage correct according to the rules of the grammar (48%, with confidence intervals of 46% to 50%) indicated chance performance. A two-way ANOVA

comparing the percentage o f items classified as grammatical (Y responses), with both grammaticality and ACS as within-subjects variables, found a significant effect of ACS, F (1, 20) = 31.30, M SE = 790.63, but no effect of grammaticality, F (1, 20) = 2.37, M SE = 89.24, and no Grammaticality x ACS interaction, F (1, 20) = 2.80, MSE = 85.28. The sums of squares calculated for the ANOVA indicated that ACS

knowledge accounted for 42% of the variance in classification performance, whereas grammaticality accounted for less than 1% o f the variance. These results entirely

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