Unbiased post-error slowing in interference tasks: A confound and a simple solution

We typically slow down after committing an error, an effect termed post-error slowing (PES). Traditionally, PES has been calculated by subtracting post-correct from post-error RTs. Dutilh et al. (Journal of Mathematical Psychology, 56(3), 208-216, 2012), however, showed PES values calculated in this way are potentially biased. Therefore, they proposed to compute robust PES scores by subtracting pre-error RTs from post-error RTs. Based on data from a large-scale study using the flanker task, we show that both traditional and robust PES estimates can be biased. The source of the bias are differential imbalances in the percentage of congruent vs. incongruent post-correct, pre-error, and post-error trials. Specifically, we found that post-correct, pre-error, and post-error trials were more likely to be congruent than incongruent, with the size of the imbalance depending on the trial type as well as the length of the response-stimulus interval (RSI). In our study, for trials preceded by a 700-ms RSI, the percentages of congruent trials were 62% for post-correct trials, 66% for pre-error trials, and 56% for post-error trials. Relative to unbiased estimates, these imbalances inflated traditional PES estimates by 37% (9 ms) and robust PES estimates by 42% (16 ms) when individual-participant means were calculated. When individual-participant medians were calculated, the biases were even more pronounced (40% and 50% inflation, respectively). To obtain unbiased PES scores for interference tasks, we propose to compute unweighted individual-participant means by initially calculating mean RTs for congruent and incongruent trials separately, before averaging congruent and incongruent mean RTs to calculate means for post-correct, pre-error and post-error trials.

Potential of Using Formalized Parameters for Modeling Speech Action

The quantitative parameters characterizing direct and indirect connections of words in the composition of the associative field “polite” are studied on the basis of the “Project of a multilingual associative thesaurus of politeness”. The aim of the study is to substantiate the potential of using formalized parameters when analyzing the stimulus-response ratio as a speech action. To achieve this goal, a free associative experiment, general scientific methods of analysis, synthesis and generalization were used. The functions of the index of direct and inverse associative strength, the number of mediations, the index of the associative power of mediation, the number of intersecting associates and the associative power of overlap are considered. The index of direct associative strength is used to calculate the probability of activation of a combination of stimulus — response, and the index of inverse associative strength reveals the degree of operationality of the corresponding combinations of response — stimulus. Analysis of the mediation parameter makes it possible to determine the number of potential signs, on the basis of which predication from stimulus to reaction is carried out. The index of the associative power of mediation characterizes the operationality of the ratio of stimulus - reaction, etc. The effectiveness of the use of formalized quantitative parameters in the modeling of speech action is proved.

Manipulations of the Response-Stimulus Intervals as a Factor Inducing Controlled Amount of Reaction Time Intra-Individual Variability

Aggrandized fluctuations in the series of reaction times (RTs) are a very sensitive marker of neurocognitive disorders present in neuropsychiatric populations, pathological ageing and in patients with acquired brain injury. Even though it was documented that processing inconsistency founds a background of higher-order cognitive functions disturbances, there is a vast heterogeneity regarding types of task used to compute RT-related variability, which impedes determining the relationship between elementary and more complex cognitive processes. Considering the above, our goal was to develop a relatively new assessment method based on a simple reaction time paradigm, conducive to eliciting a controlled range of intra-individual variability. It was hypothesized that performance variability might be induced by manipulation of response-stimulus interval’s length and regularity. In order to verify this hypothesis, a group of 107 healthy students was tested using a series of digitalized tasks and their results were analyzed using parametric and ex-Gaussian statistics of RTs distributional markers. In general, these analyses proved that intra-individual variability might be evoked by a given type of response-stimulus interval manipulation even when it is applied to the simple reaction time task. Collected outcomes were discussed with reference to neuroscientific concepts of attentional resources and functional neural networks.

Decay of inhibition in motor imagery

During motor imagery, global inhibition and effector-specific inhibition contribute to prevent actual movements. We investigated the decay of inhibition using an action-mode switching paradigm. Participants switched between imagined and executed hand movements. Response–stimulus intervals (RSIs) were varied (200, 700, 1,300, and 2,000 ms). As inhibition (due to imagination) or activation (due to execution) in one trial affects performance in the subsequent trial, we analysed sequential effects. Evidence for the contribution of global inhibition (e.g., switch benefits in execution [E]—imagination [I] sequences compared with I-I sequences) and effector-specific inhibition (e.g., hand repetition costs after an imagination trial) was observed. Sequential effects decreased with increasing RSIs, indicating that both forms of inhibition are subject to decay. However, the decrease of sequential effects was less pronounced for global inhibition than for effector-specific inhibition. This indicates that global inhibition may decay slowly, whereas effector-specific inhibition decays rather quickly. In conclusion, global inhibition may be at least partly implemented in all contexts in which motor imagery has to be performed, whereas effector-specific inhibition may contribute to motor imagery only as soon as the exact movement parameters are known and may decay quickly after the imagined movement has been performed.

Unusual Pattern of Reading Errors in a Patient with Posterior Cortical Atrophy

Posterior cortical atrophy (PCA) is a degenerative condition characterized by a progressive deterioration of visual processing. Dyslexia constitutes an early and frequent visual symptom of the disease and previous comprehensive investigations in series of individuals have extensively documented a characteristic abundance of visual errors as the most prevalent error category in this population. Here we describe the profile of a patient with PCA, C.P., who presents an unusual prevalence of phonological, instead of purely visual, errors in his reading, in the context of an otherwise classic PCA phenotype. In keeping with the well-known PCA profile, C.P. exhibited deficits at the pre-lexical level with elements of crowding and defective early visual processing impairments but additionally showed an unusually prominent disruption of phonological processing. We also argue that our patient may have a refractory access type deficit in reading given that accuracy doubled with the introduction of a five-second response-stimulus interval. To our knowledge, no previous case of a refractory deficit affecting word reading has been reported in PCA. Our examination builds on previous knowledge about reading behaviour in PCA and describes a singular example of the rich phenotypic heterogeneity within the syndrome.

Implicit sequence learning: Inter-stimulus interval and subjective experience

In this research of implicit sequence learning we examined the difference between two groups, using constant inter-stimulus interval (ISI, 770 ms) and the standard, constant response-stimulus interval (RSI, 170 ms) in the Alternating Serial Reaction Time (ASRT) task (Howard & Howard, 1997). Moreover, we examined the subjective experience of participants during the task with three short questions about three factors: boredom, anxiety, and whether the participant concentrated on accuracy or rather on speed. In case of constant response-stimulus interval, the inter-stimulus interval were shorter, the responses were faster, but there was no difference in accuracy or learning. In the case of constant inter-stimulus interval, we found a correlation between learning and accuracy, while this correlation was not present in the case of constant response-stimulus interval. The participants got increasingly bored, their anxiety did not change, but they were concentrating more and more on speed – this latter tendency was significantly diminished in the case of constant inter-stimulus interval. In respect of these factors we did not find any other difference between the two groups. In the case of constant response-stimulus interval we found a significant negative correlation between boredom and learning, while this correlation was not found in the case of constant inter-stimulus interval. No other correlations were found between learning and subjective factors.