Cognitively demanding stimuli can acquire positive valence.

Generally, people tend to avoid stimuli that require mental effort; effort can generate negative emotions. However, employing mental effort can also promote positive emotions, given a successful outcome. We investigated whether the level of cognitive effort associated with stimuli will elicit positive or negative emotions. In Experiment 1, participants performed a gender Stroop task during the association phase. The actors from the Stroop task expressed emotionlessness, while half of the actors were displayed in the mostly incongruent (MI) condition and the rest in the mostly congruent (MC) condition. In the transfer phase, we used the same actors for the emotion discrimination task, and the actors expressed a positive emotion half of the time and a negative emotion for the other half. For the MI actors, participants responded faster to positive emotion than to negative emotion, but this difference was not significant for the MC actors. In Experiment 2, the association phase involved a task switching paradigm in which half of the actors were presented in the mostly switching (MS) condition and the other in the mostly repetition (MR) condition. In the transfer phase, the same individuals' faces were used for emotion discrimination. For the MS actors, but not the MR actors, the responses were faster to positive emotion than to negative emotion. Our results imply that stimuli associated with more cognitive effort (i.e., MI and MS stimuli) may be perceived as more positive after a successful outcome of a task, although future research is required to replicate these findings.

Stimuli with a positive valence can facilitate cognitive control.

In the process of interacting with people and objects, humans assign affective valence. By using an association-transfer paradigm, the current study investigated whether the emotion associated with a stimulus would have an impact on cognitive control outcomes. During the association phase of two experiments reported here, participants identified the emotion expressed by an actor's face as either positive (i.e., smiling) or negative (i.e., frowning). Half of the actors expressed positive emotions (MP) on 80% of trials, while the other half expressed negative emotions (MN) on 80% of trials. We tested the cognitive effect of these associations in two experiments. In the transfer phase of Experiment 1, the same actors from the association phase were shown with neutral expression during a gender Stroop task, requiring participants to identify the gender of the face while ignoring a gender word (congruent or incongruent) that was imposed upon the face. The Stroop effect was significant for the MN faces, but the effect disappeared for the MP faces. In the transfer phase of Experiment 2, the emotionless faces were presented in a task-switching paradigm, in which participants identified the age (i.e., old or young) or the gender depending on the task cue. The task switch cost was smaller (though significant) for the MP faces than for the MN faces. These results suggest that, relative to social stimuli associated with negative expressions, social stimuli associated with positive expressions can promote better cognitive control and inhibit distractor interference in goal-oriented behavior.

Perceived conflict may be negative but resolved conflict is not.

The current study investigated how exposure to a conflict stimulus influences the judgment of a subsequent stimulus's valence. We used an affective priming paradigm, presenting a color Stroop stimulus as a prime and a face as a target for an emotion recognition task. When the task for the prime was passive viewing (Experiment 1), congruent primes resulted in faster responses to emotionally positive targets than negative targets. However, this positivity bias disappeared following incongruent primes. In Experiment 2, instead of passive viewing, participants were asked to indicate the congruency of the prime, and the positivity bias was significant following the congruent prime but not following the incongruent prime. In Experiments 3 and 4, participants performed the conventional Stroop task on the prime, therefore resolving the conflict when the prime was incongruent. Experiment 3 adopted an equal proportion of congruent and incongruent primes. Experiment 4 adopted twice as many congruent primes as incongruent primes. In both experiments, the positivity bias was not significant regardless of the congruency of the prime. These results suggest that detecting conflict may interfere with positive affect or promote negative affect, therefore reducing the positivity bias. Once the conflict is resolved, however, the negative valence may disappear.

Neutral but not in the middle: cross-cultural comparisons of negative bias of "neutral" emotional stimuli.

Previous studies have shown that the perception of neutral emotion stimuli can be negative rather than absolutely neutral. In the current study, we examined the negative bias of both neutral faces and scenes, cross-culturally between East Asians (e.g. Koreans) and Caucasian Americans. In all experiments, participants performed a Go/No-go task, by either executing or withholding a response toward neutral stimuli presented in the context of positive or negative stimuli. Differentiating neutral stimuli from negative stimuli was less accurate, measured in d', than doing so from positive stimuli. This negative bias was evident with both faces (Experiments 1 and 2) and scenes (Experiment 3). In all experiments, while both ethnic groups demonstrated significant negative biases, there was a subtle modulation of the bias by cultural background. For example, for Korean faces and IAPS scenes, Koreans showed a mitigated negative bias and Caucasian Americans demonstrated a greater negative bias. However, for Caucasian faces, bias was comparable between the two groups. With the possibility of cultural modulation, the prevalent negative bias of neutral emotion questions the validity of the neutrality assumption of the neutral emotion. The study discusses the necessity of methodological and theoretical reconsiderations for the utilisation of neutral emotion stimuli.

Behavioral equivalence, but not neural equivalence--neural evidence of alternative strategies in mathematical thinking.

In a functional magnetic resonance imaging study, we investigated how people solve mathematically equivalent problems presented in two alternative formats: verbal, story format or symbolic, equation format. Although representation format had no effect on behavior, anterior prefrontal activation was greater in the story condition and posterior parietal activation was greater in the equation condition. These results show that there exist alternative neural pathways that implement different and yet equally efficient problem-solving strategies.

Viewpoint alignment and response conflict during spatial judgment.

Spatial judgment (e.g., identifying the relative location, such as left or right, of a target) from a reference point becomes more difficult with increasing disparity between the relevant allocentric viewpoint and the observer-centered viewpoint. The viewpoint alignment hypothesis suggests that this misalignment effect is due to a realignment process that reconciles two viewpoints, implying that providing an advance cue for a viewpoint should facilitate the subsequent judgment. We examined whether advance viewpoint information can reduce the misalignment effect and whether the misalignment effect reflects response conflict, as well as realignment of viewpoints. In Experiment 1, the misalignment effect decreased with advance viewpoint information, suggesting that the misalignment effect indeed reflects viewpoint realignment. In Experiment 2, the misalignment effect was greater with spatial response codes that might conflict with the spatially arranged response keys than with arbitrary responses with no such conflict. These results suggest that the misalignment effect may arise from both viewpoint realignment and response conflicts.

Differential fan effect and attentional focus.

As people study more facts about a concept, it takes longer to retrieve a particular fact about that concept. This fan effect (Anderson, 1974) has been attributed to competition among associations to a concept. Alternatively, the mental-model theory (Radvansky & Zacks, 1991) suggests that the fan effect disappears when the related concepts are organized into a single mental model. In the present study, attentional focus was manipulated to affect the mental model to be constructed. One group of participants focused on the person dimension of person-location pairs, whereas the other group focused on the location dimension. The result showed that the fan effect with the focused dimension was greater than the fan effect with the nonfocused dimension, which is contrary to the mental-model theory. The number of associations with a concept is indeed crucial during retrieval, and the importance of the information seems to be accentuated with attentional focus.

An information-processing model of the BOLD response in symbol manipulation tasks.

Two imaging experiments were performed--one involving an algebraic transformation task studied by Anderson, Reder, and Lebiere (1996) and the other an abstraction symbol manipulation task studied by Blessing and Anderson (1996). ACT-R models exist that predict the latency patterns in these tasks. These models require activity in an imaginal buffer to represent changes to the problem representation, in a retrieval buffer to hold information from declarative memory, and in a manual buffer to hold information about motor behavior. A general theory is described about how to map activity in these buffers onto the fMRI blood oxygen level dependent (BOLD) response. This theory claims that the BOLD response is integrated over the duration that a buffer is active and can be used to predict the observed BOLD function. Activity in the imaginal buffer is shown to predict the BOLD response in a left posterior parietal region; activity in the retrieval buffer is shown to predict the BOLD response in a left prefrontal region; and activity in the manual buffer is shown to predict activity in a motor region. More generally, this article shows how to map a large class of information-processing theories (not just ACT-R) onto the BOLD response and provides a precise interpretation of the cognitive significance of the BOLD response.

Implicit temporal tuning of working memory strategy during cognitive skill acquisition.

Complex cognitive tasks such as multiple-step arithmetic entail strategies for coordinating mental processes such as calculation with processes for managing working memory (WM). Such strategies must be sensitive to factors such as the time needed for calculation. In 2 experiments we tested whether people can learn the timing constraints on WM demands when those constraints are implicitly imposed. We varied the retention period for intermediate results using the well-known digit size effect: The larger the operands, the longer it takes to perform addition. During learning participants practiced multiple-step arithmetic routines combined with large or small digits. At transfer, they performed both practiced and novel combinations. Practice performance was affected by digit size and WM demands. However, the transfer performance was not fully explained by the digit size effect or the practice effect. We argue that participants acquired temporal tuning of the WM strategy to the implicit retention interval imposed by the digit size and kept using the tuning mode to unpracticed data set.

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.

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.

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.

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.

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.

An information-processing model of three cortical regions: evidence in episodic memory retrieval.

ACT-R (Anderson, J.R., et al., 2003. An information-processing model of the BOLD response in symbol manipulation tasks. Psychon. Bull. Rev. 10, 241-261) relates the inferior dorso-lateral prefrontal cortex to a retrieval buffer that holds information retrieved from memory and the posterior parietal cortex to an imaginal buffer that holds problem representations. Because the number of changes in a problem representation is not necessarily correlated with retrieval difficulties, it is possible to dissociate prefrontal-parietal activations. In two fMRI experiments, we examined this dissociation using the fan effect paradigm. Experiment 1 compared a recognition task, in which representation requirement remains the same regardless of retrieval difficulty, with a recall task, in which both representation and retrieval loads increase with retrieval difficulty. In the recognition task, the prefrontal activation revealed a fan effect but not the parietal activation. In the recall task, both regions revealed fan effects. In Experiment 2, we compared visually presented stimuli and aurally presented stimuli using the recognition task. While only the prefrontal region revealed the fan effect, the activation patterns in the prefrontal and the parietal region did not differ by stimulus presentation modality. In general, these results provide support for the prefrontal-parietal dissociation in terms of retrieval and representation and the modality-independent nature of the information processed by these regions. Using ACT-R, we also provide computational models that explain patterns of fMRI responses in these two areas during recognition and recall.

Stimulus-related priming during task switching.

Task switch cost (the deficit of performing a new task vs. a repeated task) has been partly attributed to priming of the repeated task, as well as to inappropriate preparation for the switched task. In the present study, we examined the nature of the priming effect by repeating stimulus-related processes, such as stimulus encoding or stimulus identification. We adopted a partial-overlap task-switching paradigm, in which only stimulus-related processes should be repeated or switched. The switch cost in this partial-overlap condition was smaller than the cost in the full-overlap condition, in which the task overlap involved more than stimulus processing, indicating that priming of a stimulus is a component of a switch cost. The switch cost in the partial-overlap condition, however, disappeared eventually with a long interval between two tasks, whereas the cost in the full-overlap condition remained significant. Moreover, the switch cost, in general, did not interact with foreknowledge, suggesting that preparation on the basis of foreknowledge may be related to processes beyond stimulus encoding. These results suggest that stimulus-related priming is automatic and short-lived and, therefore, is not a part of the persisting portion of switch cost.

Competition and representation during memory retrieval: roles of the prefrontal cortex and the posterior parietal cortex.

In this functional-MRI study we examined the hypothesis that the prefrontal cortex responds differently to the extent of competition during retrieval, whereas the parietal cortex is responsible for problem representation that should not be directly related to the competition. Participants mastered arbitrary person-location pairs, and their recognition memory was tested in a functional-MRI session. The pairs were constructed such that a person was associated with one, two, or three different locations and vice versa. The recognition time increased with the number of associations, reflecting increased competition. A confirmatory analysis of imaging data with prespecified prefrontal and parietal regions showed that, although both regions were highly involved during memory retrieval, only the prefrontal region responded to the levels of competition. This result was consistent with predictions of an information-processing model as well as with an exploratory identification of regions of interest.

Predicting the practice effects on the blood oxygenation level-dependent (BOLD) function of fMRI in a symbolic manipulation task.

Based on adaptive control of thought-rational (ACT-R), a cognitive architecture for cognitive modeling, researchers have developed an information-processing model to predict the blood oxygenation level-dependent (BOLD) response of functional MRI in symbol manipulation tasks. As an extension of this research, the current event-related functional MRI study investigates the effect of relatively extensive practice on the activation patterns of related brain regions. The task involved performing transformations on equations in an artificial algebra system. This paper shows that the base-level activation learning in the ACT-R theory can predict the change of the BOLD response in practice in a left prefrontal region reflecting retrieval of information. In contrast, practice has relatively little effect on the form of BOLD response in the parietal region reflecting imagined transformations to the equation or the motor region reflecting manual programming.