Biomedical subjects

Frederick Verbruggen

Publications and source records attributed to Frederick Verbruggen.

10 recordsLinked to original sources

PubMed2006

Selective stopping in task switching: The role of response selection and response execution.

Recently, several studies stressed the role of response selection in cued task switching. The present study tried to investigate directly the hypothesis that no switch cost can be found when there was no response selection. In two experiments, we combined a cued task switching paradigm with the selective stopping paradigm. Results of the experiments demonstrated that a switch cost was found when participants selected a response, even without response execution. Alternatively, when the response was inhibited without the need of response selection, no switch cost was found. These results provide direct evidence for the distinct role of response selection in cued task switching and suggest that response execution is not a necessary factor to obtain a switch cost.

Choice Behavior↗

PubMed2006

The effect of interference in the early processing stages on response inhibition in the stop signal task.

In the present study, the relation between interference at the early processing stages and response inhibition was investigated. In previous studies, response stopping appeared to be slowed down when irrelevant distracting information was presented. The purpose of the present study was to further explore the relationship between interference control and response inhibition. In Experiment 1, a stop signal paradigm was combined with a global/local task. The typical global-to-local interference effect is generally attributed to early processing stages, such as stimulus perception and identification. Results of this experiment demonstrated a congruency effect for both reaction time data and stopping performance. In Experiment 2, these results were replicated with a flanker task that used stimulus-incongruent but response-congruent flankers. Results of both experiments suggest that response inhibition and interference at the early processing stages interact.

Female↗

PubMed2006

Tscope: A C library for programming cognitive experiments on the MS windows platform.

Tscope is a C/C+ + programming library designed for programming experiments that run on Windows 2000/XP. It is intended for a public of experimental psychologists with moderate programming skills, who are accustomed to writing their own experimental programs for DOS but have not made the step to Windows-based programming yet. It provides molecular functions for graphics, sound, timing, randomization, and response registration. Together with ANSI-C standard library functions and the powerful C syntax, this set of functions gives the experimenter the opportunity to program virtually any experiment one can come up with. Tscope is completely based on free software, is distributed under the GNU General Public License, and is available at expsy.ugent.be/tscope. An integrated development environment for compiling and running Tscope programs is also freely available.

Cognition↗

PubMed2006

Top-down and bottom-up sequential modulations of congruency effects.

Several studies have demonstrated reduced congruency effects after incongruent trials. The conflict monitoring hypothesis (Botvinick, Braver, Barch, Carter, and Cohen, 2001) assumes that this sequential modulation is based on top-down cognitive control and suggests that more control is engaged after the detection of conflict. An alternative account is based on repetition effects of stimulus and response features and can be considered bottom up. This study investigates both modulatory sources. In a Stroop task with two response-stimulus intervals (RSIs), we demonstrate that top-down modulation does not occur with a very short RSI, suggesting that it takes some time before the system can be reconfigured. Bottom-up modulation is observed for both RSIs. This finding demonstrates that two different sources simultaneously reduce congruency effects after incongruent trials.

Adolescent↗

PubMed2006

Stimulus- and response-conflict-induced cognitive control in the flanker task.

Recently, several studies have been conducted to investigate the top-down adjustments made after incongruent trials during conflict tasks. In the present study, we investigated conflict monitoring with different types of conflict. In a modified version of the flanker task, a distinction was made between stimulus-stimulus conflict and stimulus-response conflict. Six colors were mapped to three responses in order to exclude all sequences in which a relevant or an irrelevant stimulus- or response-related feature was repeated from trial n-1 to trial n. An analysis of the effect of the congruency of the previous trial demonstrated that conflict adaptation was present. The stimulus congruency effect was reduced after both a stimulus-incongruent trial and a response-incongruent trial. The response congruency effect did not vary as a function of previous congruency. These findings are discussed in relation to the distinction between conflict detection and conflict regulation.

Adult↗

PubMed2005

Effects of stimulus-stimulus compatibility and stimulus-response compatibility on response inhibition.

Previous studies demonstrated that interference control in stimulus-stimulus compatibility tasks slowed down stopping in the stop signal task (e.g., Kramer, A. F., Humphrey, D. G., Larish, J. F., Logan, G. D., & Strayer, D. L. (1994). Aging and inhibition: beyond a unitary view of inhibitory processing in attention. psychology and aging, 9, 491-512). In the present study, the impact of stimulus-stimulus compatibility and stimulus-response compatibility on response inhibition is further investigated. In Experiment 1, the stop signal task was combined with a traditional horizontal Simon task and with a vertical variant. For both dimensions, stopping responses was prolonged in incompatible trials, but only when the previous trial was compatible. In Experiment 2, the Simon task was combined with a spatial Stroop task in order to compare the effects of stimulus-stimulus and stimulus-response compatibility. The results demonstrated that both types of compatibility influenced stopping in a similar way. These findings are in favor of the hypothesis that response inhibition in the stop signal task and interference control in conflict tasks rely on similar mechanisms.

Attention↗

PubMed2005

Inhibiting responses when switching: Does it matter?

In the present study, cued task-switching was combined with the stop-signal paradigm in order to investigate the interaction between response inhibition and task-switching. In line with earlier findings from Schuch and Koch (2003), the results show that switch and repetition trials following inhibited responses were processed equally fast. This confirms the hypothesis of Schuch and Koch (2003) that after signal-inhibit trials there is less interference, resulting in a disappearance of the switch cost. Furthermore, stopping performance was not affected by task-switching. The estimated stop-signal latencies were similar for switch and repetition trials, while the stop-signal delays were longer for switch compared to repetition trials. This result suggests that response inhibition and the inhibition processes in cued task-switching are not relying upon a common mechanism.

Cognition↗

PubMed2005

The phonological loop in task alternation and task repetition.

It has recently been proposed that task repetition is easier than task alternation because the appropriate task settings are already present in working memory, whereas during task alternation task settings must be retrieved from long-term memory (Mayr & Kliegl, 2000). The present study tested whether the phonological loop is involved in keeping the relevant task settings active in working memory. It may then be expected that concurrent articulatory suppression would diminish the facilitation associated with task repetition because the phonological loop could no longer maintain the appropriate task settings active in working memory. Both during task repetition and task alternation the relevant task settings should then be retrieved from long-term memory. Three dual-task experiments were conducted. The results of Experiment 1 were in support of our prediction. Experiment 2 replicated the findings of Experiment 1 and showed that the task settings probably represent the adequate response mappings. Experiment 3 ruled out the involvement of the visuo-spatial sketchpad and more general coordination demands during dual tasking.

Attention↗

PubMed2004

On the difference between response inhibition and negative priming: evidence from simple and selective stopping.

Negative priming is a commonly observed after-effect in studies concerning inhibition. Effects of the preceding trial are also found in other paradigms, like the stop signal paradigm. In the present study, stop signals were introduced in a negative priming paradigm and the relation between stop signal inhibition and negative priming was investigated. In Experiment 1, we used a simple stop signal task. Stopping data clearly suggest that stopping performance was not influenced by negative priming. Interestingly, on no-signal probes the negative priming effect disappeared after successful inhibition of the response on the prime trial. On the contrary, when inhibition failed, the negative priming effect remained. In Experiment 2, we used the selective stop signal task. As in Experiment 1, inhibition of motor responses was not influenced by negative priming. The hypothesis that negative priming disappeared due to a general nonspecific stop was confirmed in this experiment, as a negative priming effect was found after both successful and unsuccessful behavioral inhibition. The results of both experiments show that response inhibition is not influenced by negative priming, and that negative priming is only affected after a successful general stop.

Analysis of Variance↗

PubMed2004

The interaction between stop signal inhibition and distractor interference in the flanker and Stroop task.

In the present study, two experiments were conducted to investigate the interaction between the behavioral inhibition, measured by the stop signal task, and distractor interference, measured by the flanker task and the Stroop task. In the first experiment, the stop signal task was combined with a flanker task. Analysis revealed that participants responded faster when the distractors were congruent to the target. Also, the data suggest that it is more difficult to suppress a reaction when the distractors were incongruent. Whether the incongruent distractor was part of the response set (i.e. the distractor could also be a target) or not, had no influence on stopping reactions. In the second experiment, the stop signal task was combined with a manual version of the Stroop task and the degree of compatibility was varied. Even though in the second experiment of the present study interference control is differently operationalized, similar results as in the first experiment were found, indicating that inhibition of motor responses is influenced by the presentation of distracting information that is not part of the response set.

Analysis of Variance↗