Study time effects in recognition memory

We empirically tested the assumption that study time increases recognition accuracy because the storage of information is better when study time is longer as Shiffrin and colleagues have reported, an assumption common to parallel models of recognition. In the present study with 123 subjects, we examined the effect of item strength on four measures: hit rate, false alarm rate, d', and beta, for a single-word recognition task with longer study times than those usually used in the literature. Analysis indicated significant increase for hit rate and d' and a decrease in false alarm rate, as one goes from weak to stronger study conditions, and a change in ln(beta) when study time is greater than 1 sec. These results suggest that familiarization is one, but not the only, factor underlying the strength-mirror effect.     

Credal imprecision and the value of evidence

This paper is about a tension between two theses. The first is Value of Evidence: roughly, the thesis that it is always rational for an agent to gather and use cost-free evidence for making decisions. The second is Rationality of Imprecision: the thesis that an agent can be rationally required to adopt doxastic states that are imprecise, i.e., not representable by a single credence function. While others have noticed this tension, I offer a new diagnosis of it. I show that it arises when an agent with an imprecise doxastic state engages in an unreflective inquiry, an inquiry where they revise their beliefs using an updating rule that doesn't satisfy a weak reflection principle. In such an unreflective inquiry, certain synchronic norms of instrumental rationality can make it instrumentally irrational for an agent to gather and use cost-free evidence. I then go on to propose a diachronic norm of instrumental rationality that preserves Value of Evidence in unreflective inquiries. This, I suggest, may help us reconcile this thesis with Rationality of Imprecision.     

SIMULTANEOUS-SUCCESSIVE SYNTHESES AND PLANNING IN CHINESE READERS*

The present study investigated simultaneous-successive syntheses and planning as cognitive processing constructs in 66 grade 4 and 63 grade 6 Chinese children. Principal factor and promax analyses provided evidence of the realities of these independent factors. Simultaneous and successive components contributed to composite reading with varying degrees of variance for each grade. The Luria paradigm provides a useful framework for research into patterns of readers.     

Shock intensity and signaled avoidance responding

Five rats were submitted to a signaled free-operant avoidance contingency. Throughout the experiment, shock intensity was varied from 0.1 to 8.0 mA, with shock duration constant at 200 milleseconds. Results indicate: (a) an all-or-none effect of shock intensity on response and shock rates, on percentage of shocks avoided, and on frequency of occurrence of responding during the preshock stimulus; and (b) no systematic effect of shock intensity on stimulus control, measured either by the percentage of stimulus presentations accompanied by a response or by the percentage of responses that occurred during those preshock stimuli. Such results indicate that for each subject there is a minimum shock intensity necessary to establish and maintain avoidance responding; intensities higher than this minimum value have little or no effect on responding (with an upper limit for those strong intensities with a general disruptive effect on behavior).     

Point biserial correlation coefficient and its generalization

The problem of measuring the association between two characters, one quantitative and the other qualitative, is discussed. The formula for the large sample standard error of the point biserial correlation coefficient under general conditions is derived. The point multiserial correlation coefficient is introduced and some of its properties are examined. Tests of different hypotheses appropriate to these types of problems are formulated.I wish to pay my sincerest thanks to Dr. C. R. Rao, Dr. S. K. Mitra, and the reviewers for their valuable suggestions.     

Development of planning and its relation to other cognitive processes

The purpose of this study was to (a) delineate the course of development of children's planning skills during school years, (b) examine whether different levels of planning exist, and (c) explore the role of other cognitive processes as cognitive correlates of planning. The participants were 250 students, 50 from each of the five targeted grades (3, 5, 7, 9, and 11). They each completed a battery of planning, attention, and simultaneous and successive processing tasks. MANOVA indicated that the main effect of grade was significant, whereas gender had no significant effect on planning. Pairwise comparisons of performance means between grades indicated that developmental trajectories were not uniform across planning tasks. Correlation and regression analyses showed that the relationship between planning tasks and attention, and simultaneous and successive processing scores varied as a function of the planning task and the grade level. Furthermore, two planning factors were found and cluster analyses of variables indicated that one of the tasks, Crack-the-Code, may represent a different kind of planning than the other planning tasks used.     

Priming index of the Spanish word fragments from the Dasí, Soler,and Ruiz (2004) database

Word-fragment completion is a frequently used test in implicit memory research. A database of 196 Spanish fragments was recently published (Dasí, Soler, & Ruiz, 2004) in which the fragments were described for indices, such as difficulty, familiarity, frequency, number of meanings, and so on (www.psychonomic.org/archive). In this work, a new index, the priming index, is described for the same 196 fragments. This index is calculated for each fragment by subtracting the difficulty index (the proportion of correct completion when the fragment is not studied) from the proportion of correct completion when the fragment is studied, and it means the capacity of an item to be primed. In order to determine whether the new index performs well, we have replicated some important experimental effects, such as priming, frequency, and difficulty. We consider that this index can help researchers to better select stimuli for fragment-completion tasks.