Pushing Typists Back on the Learning Curve: Memory Chunking in the Hierarchical Control of Skilled Typewriting

Hierarchical control of skilled performance depends on the ability of higher level control to process several lower level units as a single chunk. The present study investigated the development of hierarchical control of skilled typewriting, focusing on the process of memory chunking. In the first 3 experiments, skilled typists typed words or nonwords under concurrent memory load. Memory chunks developed and consolidated into long-term memory when the same typing materials were repeated in 6 consecutive trials, but chunks did not develop when repetitions were spaced. However, when concurrent memory load was removed during training, memory chunks developed more efficiently with longer lags between repetitions than shorter lags. From these results, it is proposed that memory chunking requires 2 representations of the same letter string to be maintained simultaneously in short-term memory: 1 representation from the current trial, and the other from an earlier trial that is either retained from the immediately preceding trial or retrieved from long-term memory (i.e., study state retrieval)

Proactive adjustments of response strategies in the stop-signal paradigm.

This is a postprint of an article published in Journal of Experimental Psychology: Human Perception and Performance © 2009 copyright American Psychological Association. 'This article may not exactly replicate the final version published in the APA journal. It is not the copy of record.' Journal of Experimental Psychology: Human Perception and Performance is available online at: http://www.apa.org/pubs/journals/xhp/index.aspxIn the stop-signal paradigm, fast responses are harder to inhibit than slow responses, so subjects must balance speed in the go task with successful stopping in the stop task. In theory, subjects achieve this balance by adjusting response thresholds for the go task, making proactive adjustments in response to instructions that indicate that relevant stop signals are likely to occur. The 5 experiments reported here tested this theoretical claim, presenting cues that indicated whether or not stop signals were relevant for the next few trials. Subjects made proactive response-strategy adjustments in each experiment: Diffusion-model fits showed that response threshold increased when participants expected stop signals to occur, slowing go responses and increasing accuracy. Furthermore, the results show that subjects can make proactive response-strategy adjustments on a trial-by-trial basis, suggesting a flexible cognitive system that can proactively adjust itself in changing environments

Automaticity of cognitive control: goal priming in response-inhibition paradigms.

This is a postprint of an article published in Journal of Experimental Psychology: Learning, Memory, and Cognition © 2009 copyright American Psychological Association. 'This article may not exactly replicate the final version published in the APA journal. It is not the copy of record.' The Journal of Experimental Psychology: Learning, Memory, and Cognition is available online at: http://www.apa.org/pubs/journals/xlm/index.aspxResponse inhibition is a hallmark of cognitive control. An executive system inhibits responses by activating a stop goal when a stop signal is presented. The authors asked whether the stop goal could be primed by task-irrelevant information in stop-signal and go/no-go paradigms. In Experiment 1, the task-irrelevant primes GO, ###, or STOP were presented in the go stimulus. Go performance was slower for STOP than for ### or GO. This suggests that the stop goal was primed by task-irrelevant information. In Experiment 2, STOP primed the stop goal only in conditions in which the goal was relevant to the task context. In Experiment 3, GO, ###, or STOP were presented as stop signals. Stop performance was slower for GO than for ### or STOP. These findings suggest that task goals can be primed and that response inhibition and executive control can be influenced by automatic processing

Pushing typists back on the learning curve: Revealing chunking in skilled typewriting.

Theories of skilled performance propose that highly trained skills involve hierarchically structured control processes. The present study examined and demonstrated hierarchical control at several levels of processing in skilled typewriting. In the first two experiments, we scrambled the order of letters in words to prevent skilled typists from chunking letters, and compared typing words and scrambled words. Experiment 1 manipulated stimulus quality to reveal chunking in perception, and Experiment 2 manip-ulated concurrent memory load to reveal chunking in short-term memory (STM). Both experiments manipulated the number of letters in words and nonwords to reveal chunking in motor planning. In the next two experiments, we degraded typing skill by altering the usual haptic feedback by using a laser-projection keyboard, so that typists had to monitor keystrokes. Neither the number of motor chunks (Experiment 3) nor the number of STM items (Experiment 4) was influenced by the manipulation. The results indicate that the utilization of hierarchical control depends on whether the input allows chunking but not on whether the output is generated automatically. We consider the role of automaticity in hierarchical control of skilled performance

Automatic and controlled response inhibition: associative learning in the go/no-go and stop-signal paradigms.

This is a postprint of an article published in Journal of Experimental Psychology: General © 2008 copyright American Psychological Association. 'This article may not exactly replicate the final version published in the APA journal. It is not the copy of record.' Journal of Experimental Psychology: General is available online at: http://www.apa.org/pubs/journals/xge/index.aspxIn 5 experiments, the authors examined the development of automatic response inhibition in the go/no-go paradigm and a modified version of the stop-signal paradigm. They hypothesized that automatic response inhibition may develop over practice when stimuli are consistently associated with stopping. All 5 experiments consisted of a training phase and a test phase in which the stimulus mapping was reversed for a subset of the stimuli. Consistent with the automatic-inhibition hypothesis, the authors found that responding in the test phase was slowed when the stimulus had been consistently associated with stopping in the training phase. In addition, they found that response inhibition benefited from consistent stimulus-stop associations. These findings suggest that response inhibition may rely on the retrieval of stimulus-stop associations after practice with consistent stimulus-stop mappings. Stimulus-stop mapping is typically consistent in the go/no-go paradigm, so automatic inhibition is likely to occur. However, stimulus-stop mapping is typically inconsistent in the stop-signal paradigm, so automatic inhibition is unlikely to occur. Thus, the results suggest that the two paradigms are not equivalent because they allow different kinds of response inhibition