The dimensionality of the flanker compatibility effect: a psychophysiological analysis

Further Evidence for the Binding and Retrieval of Control-States From the Flanker Task

In response-interference tasks, congruency effects are reduced in trials that follow an incongruent trial. This congruence sequence effect (CSE) has been taken to reflect top-down cognitive control processes that monitor for and intervene in case of conflict. In contrast, episodic-memory accounts explain CSEs with bottom-up retrieval of stimulus-response links. Reconciling these opposing views, an emerging perspective holds that memory stores instances of control - abstract control-states - creating a shortcut for effortful control processes. Support comes from a study that assessed CSEs in a prime-target task. Here, repeating an irrelevant context feature boosted CSEs, possibly by retrieving previously stored control-states. We present a conceptual replication using the Eriksen flanker task because previous research found that CSEs in the flanker task reflect different control mechanisms than CSEs in the prime-target task. We measured CSEs while controlling for stimulus-response memory effects and manipulated contextual information (vertical spatial location) independently from the stimulus information, which introduced the conflict (horizontal spatial location). Results replicate previous findings - CSEs increased for context-repetition compared to context-changes. This study shows that retrieval of control-states is not limited to a specific task or context feature and therefore generalizes the notion that abstract control parameters are stored into trial-specific event files.

Two processing stages of the SNARC effect

The spatial-numerical association of response codes (SNARC) effect showed that small/large numbers represented in the left/right space facilitated left/right responses, respectively. However, the processing stage (semantic representation or response selection) of the SNARC effect is still controversial. To investigate this issue, we adopted a modified magnitude comparison task in which the effects of SNARC, Stroop (semantic-representation stage), and Simon (response-selection stage) could be simultaneously induced. The processing stages of the SNARC effect were investigated by examining the interactions among these effects. According to the additive factor logic, if two effects are interactive, then they occur in the same stage; if two effects are additive, then they occur in different stages. Across two experiments, the SNARC effect interacted with the Stroop effect and with the Simon effect. These results suggested that the SNARC effect occurred in both the semantic-representation and response-selection stages and provided insight into that the SNARC effect might have two originating sources.

The neurocognitive underpinnings of the Simon effect: An integrative review of current research

For as long as half a century the Simon task - in which participants respond to a nonspatial stimulus feature while ignoring its position - has represented a very popular tool to study a variety of cognitive functions, such as attention, cognitive control, and response preparation processes. In particular, the task generates two theoretically interesting effects: the Simon effect proper and the sequential modulations of this effect. In the present study, we review the main theoretical explanations of both kinds of effects and the available neuroscientific studies that investigated the neural underpinnings of the cognitive processes underlying the Simon effect proper and its sequential modulation using electroencephalogram (EEG) and event-related brain potentials (ERP), transcranial magnetic stimulation (TMS), and functional magnetic resonance imaging (fMRI). Then, we relate the neurophysiological findings to the main theoretical accounts and evaluate their validity and empirical plausibility, including general implications related to processing interference and cognitive control. Overall, neurophysiological research supports claims that stimulus location triggers the creation of a spatial code, which activates a spatially compatible response that, in incompatible conditions, interferes with the response based on the task instructions. Integration of stimulus-response features plays a major role in the occurrence of the Simon effect (which is manifested in the selection of the response) and its modulation by sequential congruency effects. Additional neural mechanisms are involved in supporting the correct and inhibiting the incorrect response.

Vision at a glance: The role of attention in processing object-to-object categorical relations

When viewing a scene at a glance, the visual and categorical relations between objects in the scene are extracted rapidly. In the present study, the involvement of spatial attention in the processing of such relations was investigated. Participants performed a category detection task (e.g., "is there an animal") on briefly flashed object pairs. In one condition, visual attention spanned both stimuli, and in another, attention was focused on a single object while its counterpart object served as a task-irrelevant distractor. The results showed that when participants attended to both objects, a categorical relation effect was obtained (Exp. 1). Namely, latencies were shorter to objects from the same category than to those from different superordinate categories (e.g., clothes, vehicles), even if categories were not prioritized by the task demands. Focusing attention on only one of two stimuli, however, largely eliminated this effect (Exp. 2). Some relational processing was seen when categories were narrowed to the basic level and were highly distinct from each other (Exp. 3), implying that categorical relational processing necessitates attention, unless the unattended input is highly predictable. Critically, when a prioritized (to-be-detected) object category, positioned in a distractor's location, differed from an attended object, a robust distraction effect was consistently observed, regardless of category homogeneity and/or of response conflict factors (Exp. 4). This finding suggests that object relations that involve stimuli that are highly relevant to the task settings may survive attentional deprivation at the distractor location. The involvement of spatial attention in object-to-object categorical processing is most critical in situations that include wide categories that are irrelevant to one's current goals.

Phasic valence and arousal do not influence post-conflict adjustments in the Simon task

According to theoretical accounts of cognitive control, conflict between competing responses is monitored and triggers post conflict behavioural adjustments. Some models proposed that conflict is detected as an affective signal. While the conflict monitoring theory assumed that conflict is registered as a negative valence signal, the adaptation by binding model hypothesized that conflict provides a high arousal signal. The present research induced phasic affect in a Simon task with presentations of pleasant and unpleasant pictures that were high or low in arousal. If conflict is registered as an affective signal, the presentation of a corresponding affective signal should potentiate post conflict adjustments. Results did not support the hypothesis, and Bayesian analyses corroborated the conclusion that phasic affects do not influence post conflict behavioural adjustments in the Simon task.

Cognitive-behavioral therapy induces sensorimotor and specific electrocortical changes in chronic tic and Tourette's disorder

BACKGROUND

Tic disorders, such as the Gilles de la Tourette syndrome and persistent tic disorder, are neurodevelopmental movement disorders involving impaired motor control. Hence, patients show repetitive unwanted muscular contractions in one or more parts of the body. A cognitive-behavioral therapy, with a particular emphasis on the psychophysiology of tic expression and sensorimotor activation, can reduce the frequency and intensity of tics. However, its impact on motor activation and inhibition is not fully understood.

METHODS

To study the effects of a cognitive-behavioral therapy on electrocortical activation, we recorded the event-related potentials (ERP) and lateralized readiness potentials (LRP), before and after treatment, of 20 patients with tic disorders and 20 healthy control participants (matched on age, sex and intelligence), during a stimulus-response compatibility inhibition task. The cognitive-behavioral therapy included informational, awareness training, relaxation, muscle discrimination, cognitive restructuration and relapse prevention strategies.

RESULTS

Our results revealed that prior to treatment; tic patients had delayed stimulus-locked LRP onset latency, larger response-locked LRP peak amplitude, and a frontal overactivation during stimulus inhibition processing. Both stimulus-locked LRP onset latency and response-locked LRP peak amplitude normalized after the cognitive behavioral therapy completion. However, the frontal overactivation related to inhibition remained unchanged following therapy.

CONCLUSIONS

Our results showed that P300 and reaction times are sensitive to stimulus-response compatibility, but are not related to tic symptoms. Secondly, overactivity of the frontal LPC and impulsivity in TD patients were not affected by treatment. Finally, CBT had normalizing effects on the activation of the pre-motor and motor cortex in TD patients. These results imply specific modifications of motor processes following therapy, while inhibition processes remained unchanged. Given that LRPs are partially generated within the sensorimotor and supplementary motor area, the reported reduction in tic frequency and improvements of LRPs components suggest that CBT induced a physiological change in patients' motor area.

Conflict in object affordance revealed by grip force

Viewing objects can result in automatic, partial activation of motor plans associated with them—“object affordance”. Here, we recorded grip force simultaneously from both hands in an object affordance task to investigate the effects of conflict between coactivated responses. Participants classified pictures of objects by squeezing force transducers with their left or right hand. Responses were faster on trials where the object afforded an action with the same hand that was required to make the response (congruent trials) compared to the opposite hand (incongruent trials). In addition, conflict between coactivated responses was reduced if it was experienced on the preceding trial, just like Gratton adaptation effects reported in “conflict” tasks (e.g., Eriksen flanker). This finding suggests that object affordance demonstrates conflict effects similar to those shown in other stimulus–response mapping tasks and thus could be integrated into the wider conceptual framework on overlearnt stimulus–response associations. Corrected erroneous responses occurred more frequently when there was conflict between the afforded response and the response required by the task, providing direct evidence that viewing an object activates motor plans appropriate for interacting with that object. Recording continuous grip force, as here, provides a sensitive way to measure coactivated responses in affordance tasks.

[Effects of feature similarity and discrimination category in a flanker task]

Three experiments were conducted to investigate the effects of feature similarity and discrimination category in a flanker task. Gabor patches were used as target and distractor stimuli for each experiment. In the first experiment, the target turned to minus or plus 45 deg from the vertical, whereas the orientation of the distractors changed between minus and plus 45 deg by 15 deg. For the second experiment, three conditions of the target orientation were used: minus or plus 45 deg, minus 22.5 deg or plus 67.5 deg, and 0 deg or plus 90 deg. The orientation of the distractors changed between the orientations of the two targets by 22.5 deg. In the third experiment, the target turned to minus or plus 10 deg from the vertical, whereas the orientation of the distractors changed between minus and plus 40 deg by 5 deg. The results showed that responses to the target were affected by the difference between the orientations of the target and the distractors as well as the category of their orientations.

The Simon effect as tool and heuristic

On its 43rd anniversary the Simon effect can look back at a long and varied history. First treated as a curious observation with implications for human factors research, it slowly evolved not only into a valuable target of psychological theorizing itself but also into a handy means to investigate attentional operations, the representation of space and of one's body, the cognitive representation of intentional action, and executive control. This article discusses the major characteristics of the Simon effect and the Simon task that laid the ground for this success and reviews the major lines of research, theoretical developments, and ongoing controversies on and around the Simon Effect and the cognitive processes it reflects.

A mechanism for error detection in speeded response time tasks

The concept of error detection plays a central role in theories of executive control. In this article, the authors present a mechanism that can rapidly detect errors in speeded response time tasks. This error monitor assigns values to the output of cognitive processes involved in stimulus categorization and response generation and detects errors by identifying states of the system associated with negative value. The mechanism is formalized in a computational model based on a recent theoretical framework for understanding error processing in humans (C. B. Holroyd & M. G. H. Coles, 2002). The model is used to simulate behavioral and event-related brain potential data in a speeded response time task, and the results of the simulation are compared with empirical data.

Visual spatial localization conflict: an fMRI study

fMRI and ERP studies have shown that tasks comprising conflicting stimulus-response associations activate a variety of cortical regions. It remains unclear whether any of these areas are activated by all conflict tasks, or whether conflict resolution is a common property of a number of distinct anatomical regions. Several regions in frontal and parietal cortex are activated by both exogenous (position) and endogenous (arrow direction) localization cues. The present event-related fMRI study used a version of the Simon task with independent positional and directional cues. The results indicated that spatial localization conflict activated pre-motor and superior parietal regions in the right hemisphere known to be involved in spatial localization, but anterior cingulate activation did not reach threshold. This suggests that conflict within a single functional modality may be processed in the region embodying that modality, and anterior cingulate may be called on only to resolve conflict between modalities.

When complexity helps: an electrophysiological analysis of multiple feature benefits in object perception

Fournier, L. R., Eriksen, C. W. and Bowd, C. (1998. Multiple feature discrimination faster than single feature discrimination within the same object? Perception & Psychophysics 60, 1384-1405) found that judging the presence of multiple features within an object is faster than judging the presence of the least discriminable of these features alone (multiple feature benefits, MFBs). When an 'absent' response is required, responses are slower when some of the relevant (target) features are present (multiple feature costs, MFCs). The present study utilized psychophysiological measures (of the event-related brain potential and the electromyogram) to determine the contributions of response priming and stimulus evaluation processes (P300 latency) to these effects. P300 latency and reaction time (RT) both showed evidence of MFBs and MFCs. These findings suggest that MFBs and MFCs can be attributed to processing that occurs prior to response selection. No dissociations between P300 latency and RT measures were found for 'present' responses across the single and multiple feature judgements. However, for 'absent' responses, partial dissociations were found between these measures, and partial errors and longer response execution intervals were observed more often when an object contained some target features. These findings suggest that response priming contributes to MFCs, but may not contribute to MFBs.

Positive and negative compatibility effects

This paper reports a series of four experiments that established a negative compatibility effect (NCE) by which compatible distractors led to slower and less accurate target performance than did incompatible ones (Experiment 1). This effect is interpreted as an early perceptual effect that delays the attribution of visual attention over the target location in the compatible condition. This view predicted that the NCE should be observed only when attention has to be selectively attributed to the target location. In Experiments 2 and 3, this prediction was tested by manipulating the perceptual load in the display. High perceptual load displays are known to require selective attention (Lavie, 1995). Accordingly, reliable NCEs were observed when high-load displays were used. In contrast, reduced NCEs were found in displays that did not require selective attention. Experiment 4 established that the manifestation of the NCE was influenced by low-level visual cues, such as brightness and contrast. Overall, these experiments indicated that the NCE can be understood as an early perceptual effect, which arises from a conflict between the cues that guide the distribution of attention when the task requires selective attention.