Conditioned task-set competition: Neural mechanisms of emotional interference in depression

Depression has been associated with increased response times at the incongruent-, neutral-, and negative-word trials of the classical and emotional Stroop tasks (Epp et al., Clinical Psychology Review, 32, 316–328, 2012). Response-time slowdown effects at incongruent- and negative-word trials of the Stroop tasks were reported to correlate with depressive severity, indicating strong relevance of the effects to the symptomatology. This study proposes a novel integrative computational model of neural mechanisms of both the classical and emotional Stroop effects, drawing on the previous prominent theoretical explanations of performance at the classical Stroop task (Cohen, Dunbar, & McClelland, Psychological Review, 97, 332–361, 1990; Herd, Banich, & O’Reilly, Journal of Cognitive Neuroscience, 18, 22–32, 2006), and in addition suggesting that negative emotional words represent conditioned stimuli for future negative outcomes. The model is shown to explain the classical Stroop effect and the slow (between-trial) emotional Stroop effect with biologically plausible mechanisms, providing an advantage over the previous theoretical accounts (Matthews & Harley, Cognition & Emotion, 10, 561–600, 1996; Wyble, Sharma, & Bowman, Cognition & Emotion, 22, 1019–1051, 2008). Simulation results suggested a candidate mechanism responsible for the pattern of depressive performance at the classical and the emotional Stroop tasks. Hyperactivity of the amygdala, together with increased inhibitory influence of the amygdala over dopaminergic neurotransmission, could be at the origin of the performance deficits.     

Levels of processing with free and cued recall and unilateral temporal lobe epilepsy

This study investigates the role of the temporal lobes in levels-of-processing tasks (phonetic and semantic encoding) according to the nature of recall tasks (free and cued recall). These tasks were administered to 48 patients with unilateral temporal epilepsy (right "RTLE"=24; left "LTLE"=24) and a normal group (n=24). The results indicated that LTLE patients were impaired for semantic processing (free and cued recall) and for phonetic processing (free and cued recall), while for RTLE patients deficits appeared in free recall with semantic processing. It is suggested that the left temporal lobe is involved in all aspects of verbal memory, and that the right temporal lobe is specialized in semantic processing. Moreover, our data seem to indicate that RTLE patients present a retrieval processing impairment (semantic condition), whereas the LTLE group is characterized by encoding difficulties in the phonetic and semantic condition.     

Time intervals production in tapping and oscillatory motion

We applied spectral analysis on series of time intervals produced in a synchronization-continuation experiment. In the first condition intervals were produced by finger tapping, and in the second by an oscillatory motion of the hand. Results obtained in tapping were consistent with a discrete, event-based timing model. In the oscillatory condition, the spectra suggested a continuous, dynamic timing mechanism, based on the regulation of effector stiffness. It is concluded that the oscillatory character of movement can offer an important resource for timing control. The use of an event-based timing control such as postulated in the Wing-Kristoffersson model could be restricted to a quite limited class of rhythmic tasks, characterized by the concatenation of discrete events.     

Exemplars, prototypes, and the flexibility of classification models

J. P. Minda and J. D. Smith (2001) showed that a prototype model outperforms an exemplar model, especially in larger categories or categories that contained more complex stimuli. R. M. Nosofsky and S. R. Zaki (2002) showed that an exemplar model with a response-scaling mechanism outperforms a prototype model. The authors of the current study investigated whether excessive model flexibility could explain these results. Using cross-validation, the authors demonstrated that both the prototype model and the exemplar model with a response-scaling mechanism suffered from overfilling in the linearly separable category structure. The results illustrate the need to make sure that the best-fitting model is not chasing error variance instead of variance attributed to the cognitive process it is supposed to model.     

The nature of the syllabic neighbourhood effect in French

We investigated whether and how sublexical units such as phonological syllables mediate access to the lexicon in French visual word recognition. To do so, two lexical decision task (LDT) experiments examined the nature of the syllabic neighbourhood effect. In Experiments 1a and b, the number of higher frequency syllabic neighbours was manipulated while controlling for the first bigram. The results failed to show a pure syllabic neighbourhood effect. In Experiments 2a and b, syllabic neighbourhood and bigram frequency were factorially manipulated. The interaction showed that the syllabic neighbourhood effect was inhibitory when bigram frequency was high, whereas it was facilitatory when bigram frequency was low. Similar patterns of results were found in both the yes/no (Experiments 1a and 2a) and go/no-go LDTs (Experiments 1b and 2b), so varying task requirements of the lexical decision did not influence the effect. These findings are discussed in the context of parallel distributed processing and interactive-activation models, and suggest that orthographic redundancy properties contribute to the influence of phonological syllables.     

Two spheres of belief in justice: extensive support for the bidimensional model of belief in a just world

The purpose of this research comprising five studies (N = 666) was to further corroborate the bidimensional conceptualisation of the belief in a just world proposed by Lipkus et al. (1996). It was demonstrated that belief in a just world for the Self (and not for Others) was correlated to evaluations of the meaning of life. Belief in a just world for Others was significantly correlated to discrimination against the elderly, stigmatisation of poverty, and higher penal punitiveness, while belief in a just world for Self was weakly or not related to these variables. Together, these observations confirm the importance of the conceptual and psychometric distinction between these two spheres of the belief in a just world.     

How does the heel-off posture modify gait initiation parameter programming?

The authors studied the adjustment of the 2 distinct known expressions of gait velocity, the velocity of the center of gravity (CG) and the velocity of the center of foot pressure (CP) at the end of the 1st step in 2 experimental situations: natural gait initiation (the control situation, CS) and heel-off gait initiation (the test situation, TS). Gait was initiated by 7 healthy participants, from an erect spontaneous posture in the CS and from a posture with heels raised in the TS, on a force platform at 3 self-selected speed conditions. Biomechanical data from the force platform were collected in both experimental situations, and the authors used a particular gait analysis based on the differential method of Y. Brenière (2003) in order to approach velocity modulation by means of step length and frequency. Results showed that CG and CP velocities were adjusted differently during heel-off gait initiation than during natural gait initiation. CP velocity, as compared with CG velocity, was overestimated in TS. Results also established the relevance of the expression of step velocity by means of step length and frequency: The central nervous system, taking into account the specific postural constraints of each experimental situation, uses a reference value and a regulating parameter to modulate step velocity. Moreover, the contributions of 1st step length and frequency to the expression of step velocity in TS and CS were different. Thus, a specific locomotor behavior corresponds to a given experimental situation that is characterized by its own initial biomechanical constraints.     

Differential method of characterizing gait strategies from step lengths and frequencies: strategy of velocity modulation

The differential method consists of the analysis of the variation of gait parameters length, frequency, and velocity with respect to their mean values, respectively, Delta L = L - L(m), Delta f = f - f(m), and Delta v = v - vm, where L(m), f(m), and v(m) represent the mean values of those parameters. Assuming that the strategy of modulation of velocity implies that L and f are functions of v and that statistical analyses of ratios Delta L/Delta v and Delta f/Delta v have established that there is a very significant linear correlation, close to 1, between those ratios, the mathematical procedure allows one to determine the equation of step length, L = a x f + b x v + K, where a and b are the slope and the intercept of the linear regression and K is close to L(m). The equation was experimentally tested on 140 gait sequences performed by 6 participants and for gait velocities ranging from 0.6 to 2.2 m/s and was found to be very representative of all individual values. The differential method provides another way of using the derivative of velocity, v = L x f, to characterize the strategy of velocity modulation, which then permits one to determine the linear equation of velocity, v = f x L + L x f(m) - L(m) x f(m), and to show that the respective parts played by each parameter in the progression velocity are approximately equal. The author establishes the uniqueness of the different linear adjustments and discusses the differential method's own modes of use, that is, interindividually or globally.     

Effect of bilateral stimulation of the subthalamic nucleus on parkinsonian dysarthria

Never was the effect of bilateral stimulation of the subthalamic nucleus (STN) evaluated quantitatively on all the components of speech production, that is articulation, respiration and phonation, at the same time. It is the purpose of this study which uses force measurements of the articulatory organs and acoustic analysis in 16 parkinsonian patients. With STN stimulation, reaction and movement time of the articulatory organs decreased and their maximal strength, as well as their precision increased. We also noted a large beneficial effect on voice with a significant improvement in respiratory and phonatory functions.