Context-specific control and context selection in conflict tasks

This study investigated whether participants prefer contexts with relatively little cognitive conflict and whether this preference is related to context-specific control. A conflict selection task was administered in which participants had to choose between two categories that contained different levels of conflict. One category was associated with 80% congruent Stroop trials and 20% incongruent Stroop trials, while the other category was associated with only 20% congruent Stroop trials and 80% incongruent Stroop trials. As predicted, participants selected the low-conflict category more frequently, indicating that participants avoid contexts with high-conflict likelihood. Furthermore, we predicted a correlation between this preference for the low-conflict category and the control implementation associated with the categories (i.e., context-specific proportion congruency effect, CSPC effect). Results however did not show such a correlation, thereby failing to support a relationship between context control and context selection.     

Cognitive control in context: Working memory capacity and proactive control

Working memory is important for maintaining critical information in an active state to guide future behavior. The executive-attention theory of working memory capacity (WMC; Engle & Kane, 2004) argues that goal maintenance is important for response selection when stimuli are associated with competing responses. Braver, Burgess, and Gray (2007) have labeled this type of preparatory activity proactive control. Previous WMC studies have not allowed individuals to use goal information to prepare a specific response in advance of the stimulus. The current experiment used different versions of a cue-probe task to examine the relationship between individual differences in WMC and proactive control. Across three versions of the AX version of the Continuous Performance Test, the proportion of targets was manipulated to affect both the predictive validity of the A cue and the prepotency of the target response to X probes. The results indicated that the high-WMC individuals used the cue information to prepare responses in advance only when a specific probe was likely to occur. In contrast, the performance of the low-WMC individuals was less dependent upon the cue and more contingent upon overall response frequencies. The results indicate that individual differences in WMC are related to proactive control and anticipation, and important for translating cognition into action.     

The effects of training and transfer on global/local processing

We investigated interference, inhibition and transfer effects associated with training on a global-local task. Participants received 10,080 training trials on identifying local features of global/local stimuli. Global processing advantage was eliminated with practice. Global interference decreased with training whereas local interference developed with training. Transfer analyses indicated that training produced stimulus-specific effects in local processing and task-specific effects in global processing. Our findings are discussed in regards to models of global/local processing.     

Integrating faces, houses, motion, and action: spontaneous binding across ventral and dorsal processing streams

Perceiving an event requires the integration of its features across numerous brain maps and modules. Visual object perception is thought to be mediated by a ventral processing stream running from occipital to inferotemporal cortex, whereas most spatial processing and action control is attributed to the dorsal stream connecting occipital, parietal, and frontal cortex. Here we show that integration operates not only on ventral features and objects, such as faces and houses, but also across ventral and dorsal pathways, binding faces and houses to motion and manual action. Furthermore, these bindings seem to persist over time, as they influenced performance on future task-relevant visual stimuli. This is reflected by longer reaction times for repeating one, but alternating other features in a sequence, compared to complete repetition or alternation of features. Our findings are inconsistent with the notion that the dorsal stream is operating exclusively online and has no access to memory.     

Mental fatigue and the control of cognitive processes: effects on perseveration and planning

We tested whether behavioural manifestations of mental fatigue may be linked to compromised executive control, which refers to the ability to regulate perceptual and motor processes for goal-directed behaviour. In complex tasks, compromised executive control may become manifest as decreased flexibility and sub-optimal planning. In the study we use the Wisconsin Card Sorting Test (WCST) and the Tower of London (TOL), which respectively measure flexibility (e.g., perseverative errors) and planning. A simple memory task was used as a control measure. Fatigue was induced through working for 2 h on cognitively demanding tasks. The results showed that compared to a non-fatigued group, fatigued participants displayed more perseveration on the WCST and showed prolonged planning time on the TOL. Fatigue did not affect performance on the simple memory task. These findings indicate compromised executive control under fatigue, which may explain the typical errors and sub-optimal performance that are often found in fatigued people.     

Early parafoveal processing in reading Chinese sentences

The possibility that during Chinese reading information is extracted at the beginning of the current fixation was examined in this study. Twenty-four participants read for comprehension while their eye movements were being recorded. A pretarget-target two-character word pair was embedded in each sentence and target word visibility was manipulated in two time intervals (initial 140 ms or after 140 ms) during pretarget viewing. Substantial beginning- and end-of-fixation preview effects were observed together with beginning-of-fixation effects on the pretarget. Apparently parafoveal information at least at the character level can be extracted relatively early during ongoing fixations. Results are highly relevant for ongoing debates on spatially distributed linguistic processing and address fundamental questions about how the human mind solves the task of reading within the constraints of different writing systems.     

Effects of relative embodiment in lexical and semantic processing of verbs

Research examining semantic richness effects in visual word recognition has shown that multiple dimensions of meaning are activated in the process of word recognition (e.g., Yap et al., 2012). This research has, however, been limited to nouns. In the present research we extended the semantic richness approach to verb stimuli in order to investigate how verb meanings are represented. We characterized a dimension of relative embodiment for verbs, based on the bodily sense described by Borghi and Cimatti (2010), and collected ratings on that dimension for 687 English verbs. The relative embodiment ratings revealed that bodily experience was judged to be more important to the meanings of some verbs (e.g., dance, breathe) than to others (e.g., evaporate, expect). We then tested the effects of relative embodiment and imageability on verb processing in lexical decision (Experiment 1), action picture naming (Experiment 2), and syntactic classification (Experiment 3). In all three experiments results showed facilitatory effects of relative embodiment, but not imageability: latencies were faster for relatively more embodied verbs, even after several other lexical variables were controlled. The results suggest that relative embodiment is an important aspect of verb meaning, and that the semantic richness approach holds promise as a strategy for investigating other aspects of verb meaning.     

Attention, temporal predictability, and the time course of context effects in naming performance

Models of attention and context effects in naming performance should be able to account for the time course of color-word Stroop interference revealed by manipulations of the stimulus onset asynchrony (SOA) between color and word. Prominent models of Stroop task performance ( [Cohen et al., 1990], [Cohen and Huston, 1994] and [Phaf et al., 1990]) fail to account for the fact that response time (RT) and Stroop interference peak at zero SOA and diminish with word preexposure. The models may be saved by assuming that the time course of interference is determined by a strategic orienting of attention to color onsets when SOA is predictable. To test this temporal predictability hypothesis, SOA was blocked or randomly mixed in Experiment 1. In addition, the time interval between color onsets was randomly variable in Experiment 2. Although RTs were affected, none of the randomization manipulations influenced the typical shape of the time course of Stroop effects. These findings provide evidence against the temporal predictability hypothesis and thereby against prominent models of the Stroop task.     

Time pressure effects on information processing in overlapping tasks: evidence from the lateralized readiness potential

Information processing is impaired when two tasks are performed concurrently. The interference between the tasks is commonly attributed to structural bottlenecks or strategic scheduling of information processing. The present experiment investigated the effects of time pressure for the second of two responses on information processing in overlapping tasks by recording the lateralized readiness potential (LRP). Time pressure shortened the latency of the second response by diminishing the time devoted to motoric processing. In addition, task interference decreased under time pressure, which is probably due to the relatively early availability of the central bottleneck stage rather than to increased overlap of central stages. The LRP also provided direct evidence for an additional bottleneck following response selection, possibly due to supramodal refractoriness of response initiation.     

Acute aerobic exercise and information processing: Modulation of executive control in a Random Number Generation task

The immediate and short-term aftereffects of a bout of aerobic exercise on young adults’ executive functions were assessed. Sixteen participants performed a Random Number Generation (RNG) task, which measured two aspects of executive function, before, during, and after ergometer cycling exercise. In a separate session, participants completed the same sequence of testing while seated on an ergometer without pedaling. Results suggest that aerobic exercise: (1) selectively influences RNG indices related to the ability to alternate ascending and descending runs throughout the entire exercise bout; (2) induces a shift to a less effortful number generation strategy, particularly during the first few minutes of the exercise; and (3) has no significant influence on RNG performance as soon as the exercise terminates. The strategic adjustments observed during the exercise are interpreted in the framework of Hockey’s [Hockey, G. R. J. (1997). Compensatory control in the regulation of human performance under stress and high workload: A cognitive-energetical framework. Biological Psychology, 45, 73-93.] compensatory control model and suggest that concurrent effortful processes induced by cycling exercise may draw upon available attention resources and influence executive processing.     

Sentence context modulates visual word recognition and translation in bilinguals

The influence of sentence context constraint on subsequent processing of concrete and abstract cognates and noncognates was tested in three experiments. Target words were preceded by a predictive, high constraint sentence context, by a congruent, low constraint sentence context, or were presented in isolation. Dutch-English bilinguals performed lexical decision in their second language (L2), or translated target words in forward (from L1 to L2) or in backward (from L2 to L1) direction. After reading a high constraint sentence context, cognate and concreteness effects disappeared in lexical decision and strongly decreased in both translation tasks. In contrast, low constraint sentences did not influence cognate and concreteness effects. These results suggest that semantically rich sentences modulate cross-language interaction during word recognition and word translation.     

Garner interference and temporal information processing

The aim of the study was to explore whether temporal information processing can interfere with performance of a non-temporal task. A new methodology based on the Garner paradigm was employed. Participants were asked to classify two-dimensional stimuli according to either length or duration, with and without variation in the other (task-irrelevant) dimension. Garner interference was detected only with respect to classification by length when irrelevant variation in duration was present. Stroop interference was detected only in classification by length across compatible and non-compatible values of length and duration. Classification by length took more time when done with variation in duration than when duration was constant. Classification by length also took more time when length and duration were not compatible than when they were compatible. The findings indicate that the processing of duration is similar to the processing of other perceptual dimensions. The processing of duration consumes attentional resources and can interfere with the processing of other perceptual dimensions. The findings support attentional models of prospective duration judgment.     

Strategic and automatic components in the processing of linguistic spatial relations

The objective of the present study was to determine the extent to which strategies influence the representational format of a linguistic spatial relation. The propositional model assumes that a sentence describing a spatial relation is always represented as a set of propositions, whereas the strategic model claims that a spatial sentence can be represented either as a set of propositions or as a mental image, depending on the strategy (verbal or visual-spatial) an individual follows. Participants read a sentence (spatial or non-spatial) followed by a picture or sentence, which did or did not exemplify the information of the first sentence. In order to examine the involvement of strategic and automatic components the probability (20% or 80%) of the nature (sentence or picture) of the second stimulus was varied. Participants had slower verification RTs for unexpected stimuli than for expected stimuli, but this cost was significantly larger for an unexpected picture than an unexpected sentence. Furthermore, this asymmetric cost for the unexpected visual-spatial stimulus only occurred with spatial sentences and not with non-spatial sentences. Surprisingly, these data do not support a strictly propositional or a strategic model. Instead, we propose a third option: a dual representational model, in which people automatically represent the spatial sentence propositionally. In addition, depending on the context, a pictorial strategy is employed, which results in a supplementary visual-spatial representation.     

Response-repetition effects in task switching with and without response execution

Previous research into the mechanisms of task switching has shown that repeating the same response in a different task context is associated with costs. To investigate whether such response-repetition costs occur even when the first of the two responses is not overtly executed, we used a variant of the change-signal paradigm. Subjects responded to a first stimulus by pressing a left or right response key. In half of the trials, a second stimulus occurred after a variable, adaptively adjusted delay, indicating to abandon the first response, and only respond to the second stimulus using another set of left and right response keys. In Experiment 1, different tasks had to be performed with the first and second stimulus (task-switch condition); in Experiment 2, the same task had to be performed with both stimuli (task-repetition condition). Response-repetition costs were obtained in Experiment 1, and response-repetition benefits in Experiment 2. Importantly, these costs and benefits were obtained even when the first of the two responses had not been overtly executed. The data support the idea that interference of task-specific response codes occurs at the level of abstract response codes. Interference of such response codes occurs even when the responses are not overtly executed.     

Contrasting effects of interference and of breaks in interval timing

When a break is introduced during an interval to be timed, the interval is perceived shorter as break location is delayed. This is interpreted as a result of attention sharing between timing and monitoring the source of the break signal. Similar effects and interpretations are found in another context involving interfering tasks. Such tasks are assumed to induce transient interruptions in timing, comparable to those obtained with breaks. Break and interference conditions were contrasted in a temporal reproduction procedure with identical stimuli. Both conditions induced temporal underestimation and similar location effects. Similar trends occurred in a control condition where no processing of the interfering signal was required. The data suggest that expectancy, intentional processing, and automatic attraction of attention shorten temporal estimates.     

Memory for an imagined pathway and strategy effects in sighted and in totally congenitally blind individuals

The literature reports mixed results on the imagery abilities of the blind, at times showing a difference between sighted and blind individuals and at other times similarities. However, the possibility that the results are due to different strategies spontaneously used in performing the imagery tasks has never been systematically studied. A large group of 30 totally congenitally blind (TCB) individuals and a group of 30 sighted individuals matched for gender age and schooling were presented with a mental pathway task on a complex two-dimensional (5 × 5) matrix. After administering the task, participants were interviewed in order to establish the strategy they used. Results showed that both sighted and TCB may use a spatial mental imagery, a verbal or a mixed strategy in carrying out the task. Differences between the groups emerged only when last location and then entire pathway had to be remembered rather than just the last position, and were clearly affected by the type of strategy. Specifically, TCB performed more poorly than the sighted individuals when they used a spatial mental imagery strategy, whereas the two groups had a similar performance with a verbal strategy.     

Congruency sequence effect in cross-task context: Evidence for dimension-specific modulation

The congruency sequence effect refers to a reduced congruency effect after incongruent trials relative to congruent trials. This modulation is thought to be, at least in part, due to the control mechanisms resolving conflict. The present study examined the nature of the control mechanisms by having participants perform two different tasks in an alternating way. When participants performed horizontal and vertical Simon tasks in Experiment 1A, and horizontal and vertical spatial Stroop task in Experiment 1B, no congruency sequence effect was obtained between the task congruencies. When the Simon task and spatial Stroop task were performed with different response sets in Experiment 2, no congruency sequence effect was obtained. However, in Experiment 3, in which the participants performed the horizontal Simon and spatial Stroop tasks with an identical response set, a significant congruency sequence effect was obtained between the task congruencies. In Experiment 4, no congruency sequence effect was obtained when participants performed two tasks having different task-irrelevant dimensions with the identical response set. The findings suggest inhibitory processing between the task-irrelevant dimension and response mode after conflict.     

Manipulability impairs association-memory: Revisiting effects of incidental motor processing on verbal paired-associates

Imageability is known to enhance association-memory for verbal paired-associates. High-imageability words can be further subdivided by manipulability, the ease by which the named object can be functionally interacted with. Prior studies suggest that motor processing enhances item-memory, but impairs association-memory. However, these studies used action verbs and concrete nouns as the high- and low-manipulability words, respectively, confounding manipulability with word class. Recent findings demonstrated that nouns can serve as both high- and low-manipulability words (e.g., CAMERA and TABLE, respectively), allowing us to avoid this confound. Here participants studied pairs of words that consisted of all possible pairings of high- and low-manipulability words and were tested with immediate cued recall. Recall was worse for pairs that contained high-manipulability words. In free recall, participants recalled more high- than low-manipulability words. Our results provide further evidence that manipulability influences memory, likely occurring through automatic motor imagery.     

When two actions are easier than one: How inhibitory control demands affect response processing

Numerous studies showed that the simultaneous execution of multiple actions is associated with performance costs. Here, we demonstrate that when highly automatic responses are involved, performance in single-response conditions can actually be worse than in dual-response conditions. Participants responded to peripheral visual stimuli with an eye movement (saccade), a manual key press, or both. To manipulate saccade automaticity, a central fixation cross either remained present throughout the trial (overlap condition, lower automaticity) or disappeared 200 ms before visual target onset (gap condition, greater automaticity). Crucially, single-response conditions yielded more performance errors than dual-response conditions (i.e., dual-response benefit), especially in gap trials. This was due to difficulties associated with inhibiting saccades when only manual responses were required, suggesting that response inhibition (remaining fixated) can be even more resource-demanding than overt response execution (saccade to peripheral target).     

Visual processing and the bodily self

The 'body schema' has traditionally been defined as a passively updated, proprioceptive representation of the body. However, recent work has suggested that body representations are more complex and flexible than previously thought. They may integrate current perceptual information from all sensory modalities, and can be extended to incorporate indirect representations of the body and functional portions of tools. In the present study, we investigate the source of a facilitatory effect of viewing the body on speeded visual discrimination reaction times. Participants responded to identical visual stimuli that varied only in their context: being presented on the participant's own body, on the experimenter's body, or in a neutral context. The stimuli were filmed and viewed in real-time on a projector screen. Careful controls for attention, biological saliency, and attribution confirmed that the facilitatory effect depends critically on participants attributing the context to a real body. An intermediate effect was observed when the stimuli were presented on another person's body, suggesting that the effect of viewing one's own body might represent a conjunction of an interpersonal body effect and an egocentric effect.