Basics for sensorimotor information processing: some implications for learning

International audienceIn sensorimotor activities, learning requires efficient information processing, whether in car driving, sport activities or human machine interactions. Several factors may affect the efficiency of such processing: they may be extrinsic (i.e., task-related) or intrinsic (i.e., subjects-related). The effects of these factors are intimately related to the structure of human information processing. In the present article we will focus on some of them, which are poorly taken into account, even when minimizing errors or their consequences is an essential issue at stake. Among the extrinsic factors, we will discuss, first, the effects of the quantity and quality of information, secondly, the effects of instruction and thirdly motor program learning. Among the intrinsic factors, we will discuss first the influence of prior information, secondly how individual strategies affect performance and, thirdly, we will stress the fact that although the human brain is not structured to function errorless (which is not new) humans are able to detect their errors very quickly and On most of the cases), fast enough to correct them before they result in an overt failure. Extrinsic and intrinsic factors are important to take into account for learning because (1) they strongly affect performance, either in terms of speed or accuracy, which facilitates or impairs learning, (2) the effect of certain extrinsic factors may be strongly modified by learning and (3) certain intrinsic factors might be exploited for learning strategies

Sequential Compatibility Effects and Cognitive Control: Does Conflict Really Matter?

International audienceAlthough it is widely accepted that control mechanisms are necessary for human behavior tobe adapted, very little is known about how such mechanisms are recruited. A suggestion tofill the gap was put forward by M. M. Botvinick, T. S. Braver, C. S. Carter, D. M. Barch, andJ. D. Cohen (2001), who proposed the conflict-loop theory. This theory has been successfulin accounting for the reduction of compatibility effects after an incompatible trial: The levelof conflict being, on average, higher during an incompatible trial, more control occurs aftersuch a trial. The authors have tested this prediction by sorting the trials on the basis of amountof conflict (quantified by the electromyographic activity) they presented. A reduction of thecompatibility effect was observed after incompatible trials, but it was independent of the levelof conflict on previous trials, suggesting that the conflict does not trigger changes in executivecontrol. Consequences for the conflict monitoring model are discussed

Estimation of individual evoked potential by wavelet transform

ISBN : 978-2-9532965-0-1A new method to improve the signal-to-noise ratio of single evoked potentials (EP) measurements is presented, in which, contrary to previous methods, no a priori assumptions on the signal are necessary. This method is based on the wavelets decomposition of the individual signals. A statistical thresholding is applied on the coefficients of the decomposition: we estimate whether the mean value of the coefficients across trials and for each time point is significantly different from a random estimate. The performance of the method is evaluated with simulation and the method is applied to real dat

Distributional reaction time properties in the Eriksen task: marked differences or hidden similarities with the Simon task?

In conflict tasks, the irrelevant stimulus attribute needs to be suppressed for the correct response to be produced. In the Simon task, earlier researchers have proposed that this suppression is the reason that, after an initial increase, the interference effect decreases for longer RTs, as reflected by late, negative-going delta plots. This view has been challenged by observations of positive-going delta plots, even for long RTs, in other conflict tasks, despite a similar necessity for suppression. For late negative-going delta plots to be interpreted as reflecting suppression, a necessary, although maybe not sufficient, condition is that similar patterns should be observed for other conflict tasks. We reasoned that a similar suppression could be present, but hidden, in the Eriksen flanker task. By recording and analyzing electromyograms of the muscles involved in response execution, we could compute delta plots separately for trials that elicited a subthreshold incorrect response activation (partial error). Late negative-going delta plots were observable on partial-error trials, although they were weaker than for the Simon task, reducing the impact of this inversion on the overall distribution. We further showed that this pattern is modulated by time pressure. Those results indicate that mechanisms leading to negative-going delta plots, similar to those observed in the Simon task, are also at play in the Eriksen task. The link between negative-going delta plots and executive online control is discussed

Error Negativity Does Not Reflect Conflict: A Reappraisal of Conflict Monitoring and Anterior Cingulate Cortex Activity

Our ability to detect and correct errors is essential for our adaptive behavior. The conflict-loop theory states that the anterior cingulate cortex (ACC) plays a key role in detecting the need to increase control through conflict monitoring. Such monitoring is assumed to manifest itself in an electroencephalographic (EEG) component, the "error negativity" (Ne or "error-related negativity" [ERN]). We have directly tested the hypothesis that the ACC monitors conflict through simulation and experimental studies. Both the simulated and EEG traces were sorted, on a trial-by-trial basis, as a function of the degree of conflict, measured as the temporal overlap between incorrect and correct response activations. The simulations clearly show that conflict increases as temporal overlap between response activation increases, whereas the experimental results demonstrate that the amplitude of the Ne decreases as temporal overlap increases, suggesting that the ACC does not monitor conflict. At a functional level, the results show that the duration of the Ne depends on the time needed to correct (partial) errors, revealing an "on-line" modulation of control on a very short time scale

Spatial and temporal resolutions of EEG: Is it really black and white? A scalp current density view

Among the different brain imaging techniques, electroencephalography (EEG) is classically considered as having an excellent temporal resolution, but a poor spatial one. Here, we argue that the actual temporal resolution of conventional (scalp potentials) EEG is overestimated, and that volume conduction, the main cause of the poor spatial resolution of EEG, also distorts the recovered time course of the underlying sources at scalp level, and hence degrades the actual temporal resolution of EEG. While Current Source Density (CSD) estimates, through the Surface Laplacian (SL) computation, are well known to dramatically reduce volume conduction effects and hence improve EEG spatial resolution, its positive impact on EEG temporal resolution is much less recognized. In two simulation studies, we first show how volume conduction and reference electrodes distort the scalp potential time course, and how SL transform provides a much better spatio-temporal description. We then exemplify similar effects on two empirical datasets. We show how the time courses of the scalp potentials mis-estimate the latencies of the relevant brain events and that CSD provides a much richer, and much more accurate, view of the spatio-temporal dynamics of brain activity

Independent component analysis reveals the unity of cognitive control

ISBN : 978-2-9532965-0-1In reaction time tasks, when subjects commit an error, a negative wave peaking approximatively 70-100ms after the erroneous response is recorded with EEG. This negativity, called "Error (Related) Negativity" (Ne or ERN[1, 2]), is maximal fronto-centrally, above the anterior cingulate cortex and/or SMA and was first interpreted as reflecting an error detection mechanism. However, after Laplacian estimation, a similar component was later observed on correct trials [3]. If this component on correct trials were to be the same as the one observed on errors, this would put important constraints on computational models of cognitive control. To address this issue we used Independent Com- ponent Analysis (ICA) to evaluate whether a single component (in ICA terms) could account for the waves observed in both erroneous and correct trials. For all the participants, a single component that accounts for the waves observed in the three categories of trials was found. The localisation of the sources is consistent with a rostral-cingulate zone origin, where control mechanisms are likely implemented [4]. This novel use of ICA allowed us to conclude that the negativities observed on error and correct trials are reflecting the same physiological mechanism whose amplitude is modulated as function of the performance

The additivity of stimulus-response compatibility with the effects of sensory and motor factors in a tactile choice reaction time task

A tactile, two-choice, reaction time experiment is reported in which the effects of stimulus-response compatibility, response repertoire, and stimulus intensity are found to be additive. The implication of these results for the underlying information processing stage structure is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27727/1/0000119.pd