The effect of statistical learning on internal stimulus representations: Predictable items are enhanced even when not predicted

Statistical learning is the automatic and unconscious learning of environmental regularities and is a basic mechanism of learning in a variety of human perceptual and cognitive domains. Previous studies have mainly focused on the associative mechanisms of statistical learning. However, an unexplored question is whether the internal representations of individual stimuli are altered as their associations are learned. Using a temporal statistical learning paradigm, we examine this question across three experiments and find clear evidence that the internal representations of individual stimuli are differentially altered according to their degree of temporal predictability. These findings complement previous accounts of statistical learning and reveal an enriched mechanism of human learning, such that learning to associate items also enhances the representations of certain items relative to others.     

The neural basis of updating: Distinguishing substitution processes from other concurrent processes

Sörqvist, P. & Sætrevik, B. (2010). The neural basis of updating: Distinguishing substitution processes from other concurrent processes. Scandinavian Journal of Psychology, 51, 357–362. Most previous studies of updating processes have not been able to contrast processes of substituting items in memory with other concurrent processes. In the present investigation, we used a new task called “number updating” and an fMRI protocol to contrast the activation of trials that require item substitution (adding a new item to the working memory representation and suppressing an old item) with trials that involve no substitution (discarding the new item). Trials that require item substitution activated the dorsolateral prefrontal cortex, the posterior medial frontal cortex and the parietal lobes, areas typically seen activated for working memory tasks in general. Trials that do not require substitution activated the anterior medial frontal cortex. Studies examining executive functions have associated this area with cognitive conflict, and may represent suppression of the substitution processes.     

La substitution dans les études de représentations sociales : quel processus impliqué ?

This study of social representations aims at identifying the process involved in the responses produced with a substitution technique. Two alternative hypotheses are discussed: one that considers that substitution induces social comparison (Chokier and Moliner, 2006), the other suggesting that this technique leads to a reduction of normative pressures (Guimelli, 1998). In the research presented here, we studied the social representations of Drug addicts (in the tolerance towards the use of cannabis) and of Unemployed people, in order to compare the results with those obtained by Chokier and Moliner (2006) about security. With a specific population of students, these objects allowed us to manipulate two levels of distance to the object of representation. Concerning the technique of substitution, three levels of distance to the reference group (French people in general, Young people, Students) were combined into questionnaires with four types of instructions: standard, substitution, pro- and counter-normative. The PCA highlights a Guttman effect, which indicating that the responses produced with standard instruction are less normative than the responses produced with the substitution instruction to Young people. These results invalidate an explanation in terms of effect Primus Inter Pares. Globally, the results mainly show that the more the distance to the object is low and the distance to the reference group is high, the more the responses produce in substitution are seen as pro-normative and near from those produced with standard instruction. More specifically, we identified a number of inconsistencies with regard to what one could expect from an explanation of the phenomena in terms of personal versus social identity. As regards the representation of Unemployed people, the more the participants are closed to the reference group, the more the responses produced with an instruction of auto-valorization (pro-normative) are closed to those produced in substitution. However, on one hand, this result is observed only with the representation of Unemployed people, and, on the other hand, a social comparison explanation would suppose that the participants perceived the group of French people in general as homogeneous and identified themselves to this group at the same level than to the two other reference groups, which is unlikely. Finally, these results lead us to conclude that the substitution does not induce social comparison (Chokier and Moliner, 2006), but more probably reduction of normative pressures (Guimelli, 1998). It thus suggests that the study of masking effects through a substitution technique should take into account two parameters: distance to the object and distance to the reference group.     

Conflict adaptation is reflected by response interference

The conflict monitoring theory suggests that the occurrence of conflict in previous trials leads to a reduction in interference in current trials through conflict adaption. The present study included two experiments that used a colour-based flanker task and a Stroop task in combination with a 2:1 stimulus-to-response mapping manipulation and a crossing of transition types (Previous trial type×Current trial type) with stimuli to investigate conflict adaption in relation to stimulus and response interference. The results demonstrate that response interference, but not stimulus interference, was reduced following both stimuli and response conflicts in previous trials. In contrast to some recent evidence, we conclude that conflict adaptation is limited to response interference.     

The effect of stimulus variability on children's judgements of quantity

This study investigates the effect of stimulus variability on development of the ability to make quantity judgements related to area. Participants were 241 children (aged 4, 5, 6, 8, and 12 years) and 82 university students, who were asked to compare the quantities in 2 sets of 5 chocolate bars of constant width but variable length. Participants indicated which set contained more chocolate or that the amounts of chocolate were equal. Judgement accuracy of 12-year-olds and adults decreased monotonically as the variance of bar lengths increased. In younger children, performance was low when variance was very low or very high, but accuracy was higher for intermediate levels of variance, thus resulting in an inverted U-shaped effect. This pattern was confirmed in a second experiment in which we controlled for a possible age-related response bias against “equal” judgements. Findings suggest that judgements of quantity are based on a mixture of learned heuristics and comparisons of approximate quantity representations, both of which develop throughout childhood.     

An optimized facial stimuli paradigm for hybrid SSVEP+P300 brain computer interface

In this paper, hybrid BCI that merges Event Related Potentials (P300) and Steady State visual Evoked Potentials (SSVEP) simultaneously is proposed to enhance the performance of Four-choice command system. Here we integrate human facial structure in external visual stimulus to evoke stronger cortical responses in hybrid SSVEP+P300 BCI & compare it with non-face stimuli. We also addressed question of feasibility of eliciting one potential by face & other by non-face stimuli. To evoke SSVEP & P300 responses, paradigms with non-face stimuli, neutral face stimuli, and facial expression changes stimuli are proposed. We also projected additional paradigm where SSVEP is elicited by non-face and P300 by flashing different facial expressions. Results proved the last paradigm evoke stronger cortical potentials and thereby improve system accuracy and ITR than other paradigms. Author discussed external stimulus parameters that might affect simultaneous evocation of multiple brain potentials and their deterioration effect on individual potentials.     

Dissimilarity cumulation theory in smoothly connected spaces

This is the third paper in the series introducing the Dissimilarity Cumulation theory and its main psychological application, Universal Fechnerian Scaling. The previously developed dissimilarity-based theory of path length is used to construct the notion of a smooth path, defined by the property that the ratio of the dissimilarity between its points to the length of the subtended fragment of the path tends to unity as the points get closer to each other. We consider a class of stimulus spaces in which for every path there is a series of piecewise smooth paths converging to it pointwise and in length; and a subclass of such spaces where any two sufficiently close points can be connected by a smooth “geodesic in the small”. These notions are used to construct a broadly understood Finslerian geometry of stimulus spaces representable by regions of Euclidean n-spaces. With an additional assumption of comeasurability in the small between the canonical psychometric increments of the first and second kind, this establishes a link between Universal Fechnerian Scaling and Multidimensional Fechnerian Scaling in Euclidean n-spaces. The latter was a starting point for our theoretical program generalizing Fechner’s idea that sensation magnitudes can be computed by integration of a local discriminability measure.     

On minima of discrimination functions

A discrimination function ψ(x,y) assigns a measure of discriminability to stimulus pairs x,y (e.g., the probability with which they are judged to be different in a same-different judgment scheme). If for every x there is a single y least discriminable from x, then this y is called the point of subjective equality (PSE) for x, and the dependence h(x) of the PSE for x on x is called a PSE function. The PSE function g(y) is defined in a symmetrically opposite way. If the graphs of the two PSE functions coincide (i.e., g≡h⁻¹), the function is said to satisfy the Regular Minimality law. The minimum level functions are restrictions of ψ to the graphs of the PSE functions. The conjunction of two characteristics of ψ, (1) whether it complies with Regular Minimality, and (2) whether the minimum level functions are constant, has consequences for possible models of perceptual discrimination. By a series of simple theorems and counterexamples, we establish set-theoretic, topological, and analytic properties of ψ which allow one to relate to each other these two characteristics of ψ.     

Sitting on the word “chair”: Behavioral support, contextual cues, and the literal use of symbols

Recent work from an embodied-cognition perspective suggests that symbolic understanding involves bodily actions. Indeed, laboratory evidence and cultural phenomena such as magic rituals and symbolic aggression show that the behaviors evoked by a word and its referent can be quite similar to each other. In other circumstances, however, words and objects fail to display the expected degree of functional equivalence: Although we regularly sit on chairs, for example, we normally do not sit on the word “chair.” In two experiments we evaluated whether functional equivalence between word and object depended on behavioral support and contextual stimuli, as suggested by some Pavlovian views of symbolic performance. Children spent more or less time seated on a token of the word “chair,” depending on supports for sitting and background stimuli. This study may help to understand the determinants of response frequency in symbolic understanding.     

Multivariate pattern analysis of event-related potentials predicts the subjective relevance of everyday objects

Potentially decision-relevant stimuli have been proposed to undergo immediate semantic processing. The current study investigated whether information regarding the general desirability (‘Wanting’) of visually presented ‘everyday’ objects was rapidly and automatically processed. Participants completed a foreground task while their electroencephalogram (EEG) was recorded, and task-irrelevant images were presented in the background. Following this, participants rated the images with regards to Wanting and the potentially related attributes of Relevance, Familiarity, Aesthetic Pleasantness and Time Reference. Multivariate pattern classification was used to predict the ratings from patterns of EEG data. Prediction of Wanting and Relevance was possible between 100 and 150 ms following stimulus presentation. The other dimensions could not be predicted. Wanting and Relevance ratings were highly correlated and displayed similar feature weight maps. The current results suggest that the general desirability and subjective relevance of everyday objects is rapidly and automatically processed for a wide range of visual stimuli.