Improved information pooling for hierarchical cognitive models through multiple and covaried regression.

Cognitive process models are fit to observed data to infer how experimental manipulations modify the assumed underlying cognitive process. They are alternatives to descriptive models, which only capture differences on the observed data level, and do not make assumptions about the underlying cognitive process. Process models may require more observations than descriptive models however, and as a consequence, usually fewer conditions can be simultaneously modeled with them. Unfortunately, it is known that the predictive validity of a model may be compromised when fewer experimental conditions are jointly accounted for (e.g., overestimation of predictor effects, or their incorrect assignment). We develop a hierarchical and covaried multiple regression approach to address this problem. Specifically, we show how to map the recurrences of all conditions, participants, items, and/or traits across experimental design cells to the process model parameters. This systematic pooling of information can facilitate parameter estimation. The proposed approach is particularly relevant for multi-factor experimental designs, and for mixture models that parameterize per cell to assess predictor effects. This hierarchical framework provides the capacity to model more conditions jointly to improve parameter recovery at low observation numbers (e.g., using only 1/6 of trials, recovering as well as standard hierarchical Bayesian methods), and to directly model predictor and covariate effects on the process parameters, without the need for post hoc analyses (e.g., ANOVA). An example application to real data is also provided.

Measuring sequences of keystrokes with jsPsych: Reliability of response times and interkeystroke intervals.

Although the precision and reliability of response time (RT) measurements performed via Web-based interfaces have been evaluated, sequences of keystrokes have never been investigated in detail. Keystrokes often occur in much more rapid succession than RTs, and operating systems may interpret successive or concomitant keyboard events according to both automatic and user-based settings. Sequence keystroke timing could thus be more sensitive than single RTs to noise in online measurements. Here, we quantified the precision and reliability of timing measures performed during sequences of keystrokes. We used the JavaScript jsPsych library to create an experiment involving finger-movement sequences, and ran it online with 633 participants. We manipulated the structure of three keystroke motor sequences, targeting a replication of previous findings regarding both RTs and interkeystroke intervals (IKIs). Our online data accurately reproduced the original results and allowed for a novel assessment of demographic variables such as age and gender. In parallel, we also measured the objective timing accuracy of the jsPsych interface by using specialized hardware and software, showing a constant 60-ms delay for RTs and a 0-ms delay for IKIs across the sequences. The distribution of IKIs revealed quantizing for a majority of participants, most likely due to the sampling frequency of their USB keyboards. Overall, these findings indicate that JsPsych provides good reliability and accuracy in sequence keystroke timings for mental chronometry purposes, through online recordings.

Contextual modulation of hippocampal activity during picture naming.

Picture naming is a standard task used to probe language processes in healthy and impaired speakers. It recruits a broad neural network of language related areas, among which the hippocampus is rarely included. However, the hippocampus could play a role during picture naming, subtending, for example, implicit learning of the links between pictured objects and their names. To test this hypothesis, we recorded hippocampal activity during plain picture naming, without memorization requirement; we further assessed whether this activity was modulated by contextual factors such as repetition priming and semantic interference. Local field potentials recorded from intracerebral electrodes implanted in the healthy hippocampi of epileptic patients revealed a specific and reliable pattern of activity, markedly modulated by repetition priming and semantic context. These results indicate that the hippocampus is recruited during picture naming, presumably in relation to implicit learning, with contextual factors promoting differential hippocampal processes, possibly subtended by different sub-circuitries.

Evidence accumulation as a model for lexical selection.

We propose and demonstrate evidence accumulation as a plausible theoretical and/or empirical model for the lexical selection process of lexical retrieval. A number of current psycholinguistic theories consider lexical selection as a process related to selecting a lexical target from a number of alternatives, which each have varying activations (or signal supports), that are largely resultant of an initial stimulus recognition. We thoroughly present a case for how such a process may be theoretically explained by the evidence accumulation paradigm, and we demonstrate how this paradigm can be directly related or combined with conventional psycholinguistic theory and their simulatory instantiations (generally, neural network models). Then with a demonstrative application on a large new real data set, we establish how the empirical evidence accumulation approach is able to provide parameter results that are informative to leading psycholinguistic theory, and that motivate future theoretical development.

The role of orthography in speech production revisited.

The language production system of literate adults comprises an orthographic system (used during written language production) and a phonological system (used during spoken language production). Recent psycholinguistic research has investigated possible influences of the orthographic system on the phonological system. This research has produced contrastive results, with some studies showing effects of orthography in the course of normal speech production while others failing to show such effects. In this article, we review the available evidence and consider possible explanations for the discrepancy. We then report two form-preparation experiments which aimed at testing for the effects of orthography in spoken word-production. Our results provide clear evidence that the orthographic properties of the words do not influence their spoken production in picture naming. We discuss this finding in relation to psycholinguistic and neuropsychological investigations of the relationship between written and spoken word-production.

Gender congruency effects in picture naming.

The analysis of speech error corpora in various gender-marked languages has shown that noun substitutions tend to preserve grammatical gender. This result has been taken as an indication that grammatical gender could play a constraining role during the process of lexical selection. To gain insights on the status of grammatical gender in the speech production system, we discuss this hypothesis and we report three picture naming experiments. We attempted to observe gender-marked context effects in the course of error-free speech production. Participants named pictures shortly after processing a prime that was or was not gender marked and that was or was not congruent with the name of the picture. A clear congruency effect was observed, involving both facilitation in the gender congruent conditions and inhibition in gender incongruent conditions. Different interpretations of this effect and of previously reported gender context effects are discussed in the context of current models of speech production.

Semantic and associative priming in picture naming.

We report four picture-naming experiments in which the pictures were preceded by visually presented word primes. The primes could either be semantically related to the picture (e.g., "boat"--TRAIN: co-ordinate pairs) or associatively related (e.g., "nest"--BIRD: associated pairs). Performance under these conditions was always compared to performance under unrelated conditions (e.g., "flower"--CAT). In order to distinguish clearly the first two kinds of prime, we chose our materials so that (a) the words in the co-ordinate pairs were not verbally associated, and (b) the associate pairs were not co-ordinates. Results show that the two related conditions behaved in different ways depending on the stimulus-onset asynchrony (SOA) separating word and picture appearance, but not on how long the primes were presented. When presented with a brief SOA (114 ms, Experiment 1), the co-ordinate primes produced an interference effect, but the associated primes did not differ significantly from the unrelated primes. Conversely, with a longer SOA (234 ms, Experiment 2) the co-ordinate primes produced no effect, whereas a significant facilitation effect was observed for associated primes, independent of the duration of presentation of the primes. This difference is interpreted in the context of current models of speech production as an argument for the existence, at an automatic processing level, of two distinguishable kinds of meaning relatedness.

A set of 400 pictures standardized for French: norms for name agreement, image agreement, familiarity, visual complexity, image variability, and age of acquisition.

The present article provides French normative measures for 400 line drawings taken from Cycowicz, Friedman, Rothstein, and Snodgrass (1997), including the 260 line drawings that were normed by Snodgrass and Vanderwart (1980). The pictures have been standardized on the following variables: name agreement, image agreement, familiarity, visual complexity, image variability, and age of acquisition. These normative data also include word frequency values and the first verbal associate (taken from Ferrand & Alario, 1998). The six variables obtained are important because of their potential effect in many fields of psychology, especially the study of cognitive processes such as visual perception, language, and memory.