Myeong-Ho Sohn

Anticipation of conflict monitoring in the anterior cingulate cortex and the prefrontal cortex

The anterior cingulate cortex (ACC) has been suggested as a monitoring center that is responsible for online detection of response conflicts. In this view, the conflict signal detected by the ACC is transmitted to other brain regions, such as the dorsal part of the lateral prefrontal cortex (lPFC), to increase the level of cognitive control. In this functional MRI (fMRI) study, we examined the conflict resolution that goes beyond online detection of response conflicts. Participants learned pseudoarithmetic problem-solving tasks that involve stimulus–response mapping rules with high or low conflicts. On half of the trials, participants had a preview of the upcoming operator that allowed advance preparation for the mapping rules. The preview significantly reduced the conflict effects on latency. During the preview, both the ACC and lPFC were activated in anticipation of conflict, and this anticipatory activation was highly predictive of the subsequent latency. These results suggest that the ACC and lPFC are responsible for both anticipatory preparation and online adjustment in response to conflicts. The results also confirm the roles of the lPFC and ACC in managing conflict during problem solving and extend these roles to include responding to anticipation of conflicts that may arise between incompatible stimulus–response mappings maintained in working memory during preparation.

The effect of working memory capacity on conflict monitoring.

The conflict adaptation effect, a reduced interference effect upon the detection of a conflict signal (e.g., following an incongruent trial), has been interpreted as evidence for active regulation of top-down cognitive control. We hypothesized that the extent of conflict adaptation should be related to individuals working memory capacity (WMC), which has been repeatedly demonstrated to reflect the level of cognitive control. Using the Simon task, in Experiment 1, we quantified the conflict adaptation ratio (CAR) transiently as the ratio of the conflict effect following an incongruent trial to the conflict effect following a congruent trial, controlling for the reaction time that often correlates with WMC. We observed that the CAR varied from highly negative with low WMC scores to near-zero with high WMC scores. This result suggests that high WMC individuals, when detecting conflict, adjust the level of cognitive control optimally so that their performance is less susceptible to the presence of a distractor. In Experiment 2, we quantified the CAR in a sustained manner as the ratio of the conflict effect from predominantly incongruent blocks to the conflict effect from predominantly congruent blocks. Again, the CAR varied from negative to zero as WMC increased. These results suggest that WMC may reflect, in addition to the ability to maintain a level of control, the ability to adjust the level of control appropriately to the contextual demands.

Characteristics of fluent skills in a complex, dynamic problem-solving task.

We examined critical characteristics of fluent cognitive skills, using the Georgia Tech Aegis Simulation Program, a tactical decision-making computer game that simulates tasks of an anti-air-warfare coordinator. To characterize learning, we adopted the unit-task analysis framework, in which a task is decomposed into several unit tasks that are further decomposed into functional-level subtasks. Our results showed that learning at a global level could be decomposed into learning smaller component tasks. Further, most learning was associated with a reduction in cognitive processes, in which people make inferences from the currently available information. Eye-movement data also revealed that the time spent on task-irrelevant regions of the display decreased more than did the time spent on task-relevant regions. In sum, although fluency in dynamic, complex problem solving was achieved by attaining efficiency in perceptual, motor, and cognitive processes, the magnitude of the gains depended on the preexisting fluency of the component skills. These results imply that a training program should decompose a task into its component skills and emphasize those components with which trainees have relatively little prior experience. Actual or potential applications of this research include learning and training of complex tasks as well as evaluation of performance on those tasks.

Toward a real-time model-based training system

This article describes the development of a real-time model-based training system that provides adaptive over-the-shoulder (OTS) instructions to trainees as they learn to perform an Anti-Air Warfare Coordinator (AAWC) task. The long-term goal is to develop a system that will provide real-time instructional materials based on learners actions, so that eventually the initial set of instructions on a task can be strengthened, complemented, or overridden at different stages of training. The training system is based on the ACT-R architecture, which serves as the theoretical background for the cognitive model that monitors the learning process of the trainee. An experiment was designed to study the impact of OTS instructions on learning. Results showed that while OTS instructions facilitated short-term learning, (a) they took time away from the processing of current information, (b) their effects tended to decay rapidly in initial stages of training, and (c) their effects on training diminished when the OTS instructions were proceduralized in later stages of training. A cognitive model that learned from both the upfront and OTS instructions was created and provided good fits to the learning and performance data collected from human participants. Our results suggest that to fully capture the symbiotic performance between humans and intelligent training systems, it is important to closely monitor the learning process of the trainee so that instructional interventions can be delivered effectively at different stages of training. We proposed that such a flexible system can be developed based on an adaptive cognitive model that provides real-time predictions on learning and performance.

Cross-Cultural Differences in Consistent Mapping Effects of Targets and Distractors

Previous cross-cultural studies have shown that East Asians pay more attention to the background information and European Americans more to the focal object. However, it has not been well investigated what cognitive benefits can be achieved with these different attention allocation strategies. In the current study, we examined whether Koreans and European Americans differ in utilizing the regularity in targets and distractors by comparing consistent mappings (CMs) with varied mappings (VMs) of stimuli. Two experiments consistently revealed that European Americans showed a greater performance benefit with the consistency embedded within the targets (i.e., the CM target effect) but not within the distractors. In contrast, Koreans showed a greater performance benefit with the consistency within the distractors (i.e., the CM distractor effect), but not within the targets. These results imply that the East–West differences in attention allocation strategies reflect the cultural differences in utilizing the information that is potentially beneficial for task performance. We discuss what kinds of cognitive benefits can be achieved by differentially paying attention to the target and the background.

Distinct Response Components Indicate that Binding is the Primary Cause of Response Repetition Effects

Humans must constantly react to their environments. In many cases, repeating a response results in performance benefits, but sometimes it results in performance costs. This dichotomy is referred to as response repetition effects (RR effects). To understand these effects, we dissociated 2 components of a response: response categories (response meaning) and motor responses (response execution). By doing so, we were able to examine 2 proposed explanations of RR effects. One, the response inhibition account, explains that RR effects are the product of an inhibitory mechanism meant to prevent accidental reexecution of responses and stimulus category repetition priming. The response inhibition account predicts additive effects of response inhibition and stimulus category priming. Another, the binding account, explains that RR effects are the product of interference from automatically retrieved memories of previous events. The binding account predicts an interactive relationship between the transitions of task, response category, and motor response; a partial repetition of trial components (i.e., the task, the response category, and the motor response) will result in interference when compared with repeating all or switching all components. In Experiments 1 and 2, response components were dissociated by using a verification procedure. In Experiment 3, the response components were dissociated by varying the motor response used to indicate each response category. We found an interactive relationship between the transitions of task, response category, and motor response, demonstrating the role of binding in RR effects. In combination with previous results, our results suggest that binding and response inhibition are separable components of RR effects.

Analogical Symbols: The Role of Visual Cues in Long-Term Transfer

We are reminded of relevant stories, tales, or symbols from long-term memory when facing a novel problem our daily lives. Visual cues are 1 tool known to facilitate reminding. In 2 experiments, Chinese students, who had experienced a folk tale many years ago during childhood, were asked to solve an analogous problem. We tested the hypothesis that a visual cue can help bridge the gap between a novel problem and a source analogy experienced in the distant past. Different types of cues proved to have distinct influences on components of analogical problem solving. This research suggests that analogical representational features of a story or problem can be stored in long-term memory and can be activated by visual cues. The implications of these findings for theories that point to perceptual or grounded, rather than decontextualized structures in knowledge representation are discussed.

Dissociating the Components of Switch Cost Using Two-to-Two Cue―Task Mapping

In the task switch paradigm, a switch of task is typically accompanied by a change in task cue. It has been proposed that the performance deficit usually observed when switching tasks is actually the result of changing cues. To test this possibility, we used a 2:2 cue-task mapping in which each cue indicated 2 different tasks. With advance presentation of a cue, the cost associated with changing cues disappeared, though a substantial task switch cost remained. Without advance cues, the relative contributions of task switch cost and cue change cost differed by transition frequencies. The results suggest that task execution contributes to switch cost independent of cue changes.