The premotor theory of attention and the Simon effect

In the paper by Hommel (2011-this issue), the roles of the theory of event coding (TEC) and the premotor theory of attention (PMTA) for the Simon effect were considered. PMTA was treated by Hommel in terms of the proposal that attentional orienting can be viewed as the preparation of a saccade towards a certain location, and was dismissed as providing no useful contribution for an attentional explanation of the Simon effect. Here we considered a more recent and broader conception of the PMTA, compared this approach with TEC, and confronted both approaches with a few studies focusing on the role of spatial attention for the Simon effect. It was argued that PMTA may account more easily for various studies examining the influence of spatial attention on the Simon effect. We concluded our paper by listing some elements that an overall encompassing theory on the Simon effect should contain.     

The effect of a cross-trial shift of auditory warning signals on the sequential foreperiod effect

When a warning signal (WS) precedes an imperative signal (IS) by a certain amount of time (the foreperiod, FP), responses are speeded. Moreover, this effect is modulated by the FP length in the previous trial. This sequential FP effect has lately been attributed to a trace-conditioning mechanism according to which individuals learn (and re-learn) temporal relationships between the WS and the IS. Recent evidence suggests that sensory WS attributes are critical to trigger time-related response activation. Specifically, when WS modality is shifted in subsequent trials (e.g., from auditory to visual modality), the sequential FP effect becomes attenuated. This study examined whether the sequential FP effect is reduced only by between-modality shifts or whether this attenuation generalizes to cross-trial shifts of WS attributes within modalities. We compared dimensional (low vs. high tone frequency) and qualitative shifts (pure tone vs. noise) of equal-intense auditory WS events. The results of four experiments revealed that shifts of tone frequency did not, whereas shifts of qualitative tone characteristics did attenuate the sequential FP effect. These results support the view that the WS acts as a trigger cue that unintentionally activates responses at previously reinforced critical moments.     

The effect of action video game playing on sensorimotor learning: Evidence from a movement tracking task

Research on the impact of action video game playing has revealed performance advantages on a wide range of perceptual and cognitive tasks. It is not known, however, if playing such games confers similar advantages in sensorimotor learning. To address this issue, the present study used a manual motion-tracking task that allowed for a sensitive measure of both accuracy and improvement over time. When the target motion pattern was consistent over trials, gamers improved with a faster rate and eventually outperformed non-gamers. Performance between the two groups, however, did not differ initially. When the target motion was inconsistent, changing on every trial, results revealed no difference between gamers and non-gamers. Together, our findings suggest that video game playing confers no reliable benefit in sensorimotor control, but it does enhance sensorimotor learning, enabling superior performance in tasks with consistent and predictable structure.     

The effect of gender on the N1-P2 auditory complex while listening and speaking with altered auditory feedback

The effect of gender on the N1-P2 auditory complex was examined while listening and speaking with altered auditory feedback. Fifteen normal hearing adult males and 15 females participated. N1-P2 components were evoked while listening to self-produced nonaltered and frequency shifted /a/ tokens and during production of /a/ tokens during nonaltered auditory feedback (NAF), frequency altered feedback (FAF), and delayed auditory feedback (DAF; 50 and 200 ms). During speech production, females exhibited earlier N1 latencies during 50 ms DAF and earlier P2 latencies during 50 ms DAF and FAF. There were no significant differences in N1-P2 amplitudes across all conditions. Comparing listening to active speaking, N1 and P2 latencies were earlier among females, with speaking, and under NAF. N1-P2 amplitudes were significantly reduced during speech production. These findings are consistent with the notions that speech production suppresses auditory cortex responsiveness and males and females process altered auditory feedback differently while speaking.     

Adaptation to continuous perturbation of balance: progressive reduction of postural muscle activity with invariant or increasing oscillations of the center of mass depending on perturbation frequency and vision conditions

We investigated the adaptation of balancing behavior during a continuous, predictable perturbation of stance consisting of 3-min backward and forward horizontal sinusoidal oscillations of the support base. Two visual conditions (eyes-open, EO; eyes-closed, EC) and two oscillation frequencies (LF, 0.2 Hz; HF, 0.6 Hz) were used. Center of Mass (CoM) and Center of Pressure (CoP) oscillations and EMG of Soleus (Sol) and Tibialis Anterior (TA) were recorded. The time course of each variable was estimated through an exponential model. An adaptation index allowed comparison of the degree of adaptation of different variables. Muscle activity pattern was initially prominent under the more challenging conditions (HF, EC and EO; LF, EC) and diminished progressively to reach a steady state. At HF, the behavior of CoM and CoP was almost invariant. The time-constant of EMG adaptation was shorter for TA than for Sol. With EC, the adaptation index showed a larger decay in the TA than Sol activity at the end of the balancing trial, pointing to a different role of the two muscles in the adaptation process. At LF, CoM and CoP oscillations increased during the balancing trial to match the platform translations. This occurred regardless of the different EMG patterns under EO and EC. Contrary to CoM and CoP, the adaptation of the muscle activities had a similar time-course at both HF and LF, in spite of the two frequencies implying a different number of oscillation cycles. During adaptation, under critical balancing conditions (HF), postural muscle activity is tuned to that sufficient for keeping CoM within narrow limits. On the contrary, at LF, when vision permits, a similar decreasing pattern of muscle activity parallels a progressive increase in CoM oscillation amplitude, and the adaptive balancing behavior shifts from the initially reactive behavior to one of passive riding the platform. Adaptive balance control would rely on on-line computation of risk of falling and sensory inflow, while minimizing balance challenge and muscle effort. The results from this study contribute to the understanding of plasticity of the balance control mechanisms under posture-challenging conditions.