Buffer loading and chunking in sequential keypressing

Thirty-six participants practiced a task in which they continuously cycled through a fixed series of nine keypresses, each carried out by a single finger (cf. Keele & Summers, 1976). The results of the first experimental phase, the practice phase, support the notion that pauses between successive keypresses at fixed locations induces the development of integrated sequence representations (i.e., motor chunks) and reject the idea that a rhythm is learned. When different sequences were produced in the transfer phase, performance dropped considerably unless the sequence was relatively short and there was ample time for preparation. This demonstrates that motor chunks are content specific and that the absence of motor chunks shows when there is no time for advance loading of the motor buffer or the capacity of the motor buffer is insufficient to contain the entire keypressing sequence

Detecting short periods of elevated workload. A compari­son of nine workload assessment techniques

The present experiment tested the merits of 9 common workload assessment techniques with relatively short periods of workload in a car-driving task. Twelve participants drove an instrumented car and performed a visually loading task and a mentally loading task for 10, 30, and 60 s. The results show that 10-s periods of visual and mental workload can be measured successfully with subjective ratings and secondary task performance. With respect to longer loading periods (30 and 60 s), steering frequency was found to be sensitive to visual workload, and skin conductance response (SCR) was sensitive to mental workload. The results lead to preliminary guidelines that will help applied researchers to determine which techniques are best suited for assessing visual and mental workload

Representations underlying skill in the discrete sequence production task: effect of hand used and hand position

Various studies suggest that movement sequences are initially learned predominantly in effector-independent spatial coordinates and only after extended practice in effector-dependent coordinates. The present study examined this notion for the discrete sequence production (DSP) task by manipulating the hand used and the position of the hand relative to the body. During sequence learning in Experiment 1, in which sequences were executed by reacting to key-specific cues, hand position appeared important for execution with the practiced but not with the unpracticed hand. In Experiment 2 entire sequences were executed by reacting to one cue. This produced similar results as in Experiment 1. These experiments support the notion that robustness of sequencing skill is based on several codes, one being a representation that is both effector and position dependent

The effect of continuous, nonlinearly transformed visual feedback on rapid aiming movements

We investigated the ability to adjust to nonlinear transformations that allow people to control external systems like machines and tools. Earlier research (Verwey and Heuer 2007) showed that in the presence of just terminal feedback participants develop an internal model of such transformations that operates at a relatively early processing level (before or at amplitude specification). In this study, we investigated the level of operation of the internal model after practicing with continuous visual feedback. Participants executed rapid aiming movements, for which a nonlinear relationship existed between the target amplitude seen on the computer screen and the required movement amplitude of the hand on a digitizing tablet. Participants adjusted to the external transformation by developing an internal model. Despite continuous feedback, explicit awareness of the transformation did not develop and the internal model still operated at the same early processing level as with terminal feedback. Thus with rapid aiming movements, the type of feedback may not matter for the locus of operation of the internal model

The basis of S–R learning:associations between individual stimulus features and responses

Three experiments tested the hypothesis that response selection skill involves associations between individual stimulus features and responses. The Orientation group in Experiments 1 and 2 first practiced responding to the orientation of a line stimulus while ignoring its color, and the Color group practiced responding to the color of the line while disregarding its orientation. When in the ensuing test conditions the Orientation group responded to the color of the line, RTs and errors increased when the then irrelevant line orientation was inconsistent with practice. This confirmed that during practice, Orientation participants had developed orientation feature–response associations they could not fully inhibit. Yet, evidence for color feature–response associations was not observed in the Color group. This was attributed to orientation identification being faster than color identification, even after having practiced responding to colors. Experiment 3 involved practicing to three line stimuli with unique orientation and color combinations. It showed evidence for the independent development of orientation feature–response associations and color feature–response associations. Together, these results indicate that the typical RT reduction with practice in response selection tasks is caused in part by the capacity of participants to learn selecting responses on the basis of the stimulus feature that becomes available first.</p

C-SMB 2.0:Integrating over 25 years of motor sequencing research with the Discrete Sequence Production task

An exhaustive review is reported of over 25 years of research with the Discrete Sequence Production (DSP) task as reported in well over 100 articles. In line with the increasing call for theory development, this culminates into proposing the second version of the Cognitive framework of Sequential Motor Behavior (C-SMB 2.0), which brings together known models from cognitive psychology, cognitive neuroscience, and motor learning. This processing framework accounts for the many different behavioral results obtained with the DSP task and unveils important properties of the cognitive system. C-SMB 2.0 assumes that a versatile central processor (CP) develops multimodal, central-symbolic representations of short motor segments by repeatedly storing the elements of these segments in short-term memory (STM). Independently, the repeated processing by modality-specific perceptual and motor processors (PPs and MPs) and by the CP when executing sequences gradually associates successively used representations at each processing level. The high dependency of these representations on active context information allows for the rapid serial activation of the sequence elements as well as for the executive control of tasks as a whole. Speculations are eventually offered as to how the various cognitive processes could plausibly find their neural underpinnings within the intricate networks of the brain.</p