Reaction Time Benefits Research Articles

Why are some individuals better at using negative attentional templates to suppress distractors? Exploration of interindividual differences in cognitive control efficiency.

Negative templates are based on foreknowledge of distractor features and can lead to more efficient visual search at the group level. However, large individual differences exist in the size of benefits induced by negative cues. The cognitive factors underlying these interindividual differences remain unknown. Previous research has suggested higher engagement of proactive control for negative templates compared to positive templates. We thus hypothesized that interindividual differences in proactive control efficiency may explain the large variability in negative cue benefits. A large data set made up of data from two previously published studies was reanalyzed (N = 139), with eye movements recorded in 36 participants. Individual proactive control efficiency was measured through reaction time (RT) variability. Participants with higher proactive control efficiency exhibited larger benefits after negative cues across two critical measures: Individuals with higher proactive control showed larger RT benefits following negative compared to neutral cues; similarly, individuals with higher proactive control exhibited lower first saccades to cued distractor items. No such relationship was observed for positive cues. Our results confirmed the existence of large interindividual differences in the benefits induced by negative attentional templates. Critically, we show that proactive control drives these interindividual differences in negative template use. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Attentional cueing: Gaze is harder to override than arrows.

Gaze is an important and potent social cue to direct others' attention towards specific locations. However, in many situations, directional symbols, like arrows, fulfill a similar purpose. Motivated by the overarching question how artificial systems can effectively communicate directional information, we conducted two cueing experiments. In both experiments, participants were asked to identify peripheral targets appearing on the screen and respond to them as quickly as possible by a button press. Prior to the appearance of the target, a cue was presented in the center of the screen. In Experiment 1, cues were either faces or arrows that gazed or pointed in one direction, but were non-predictive of the target location. Consistent with earlier studies, we found a reaction time benefit for the side the arrow or the gaze was directed to. Extending beyond earlier research, we found that this effect was indistinguishable between the vertical and the horizontal axis and between faces and arrows. In Experiment 2, we used 100% "counter-predictive" cues; that is, the target always occurred on the side opposite to the direction of gaze or arrow. With cues without inherent directional meaning (color), we controlled for general learning effects. Despite the close quantitative match between non-predictive gaze and non-predictive arrow cues observed in Experiment 1, the reaction-time benefit for counter-predictive arrows over neutral cues is more robust than the corresponding benefit for counter-predictive gaze. This suggests that-if matched for efficacy towards their inherent direction-gaze cues are harder to override or reinterpret than arrows. This difference can be of practical relevance, for example, when designing cues in the context of human-machine interaction.

Assessing recoding accounts of negative attentional templates using behavior and eye tracking.

Can we use attentional control to ignore known distractor features? Providing cues before a visual search trial about an upcoming distractor color (negative cue) can lead to reaction time benefits compared with no cue trials. This suggests top-down control may use negative templates to actively suppress distractor features, a notion that challenges the mechanisms of top-down control provided in many theories of attention. However, there is currently mixed support for this mechanism in the literature. Alternative explanations have been proposed, which do not require suppression within top-down control but instead involve recoding the negative cue into a positive template based on color or spatial layouts. In three experiments, we contrasted the predictions of active suppression and the recoding strategies. Across experiments, we found consistent evidence against a color recoding account. We also found evidence of accuracy, reaction time, and eye movement benefits when location recoding was not possible. These results suggest that prior benefits from negative cues cannot be explained exclusively by spatial or color recoding. The results indicate that active suppression likely plays a role in the attentional benefits following negative cues. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Cerebral blood flow and immediate and sustained executive function benefits following single bouts of passive and active exercise

Passive exercise occurs when an individual’s limbs are moved via an external force and is a modality that increases cerebral blood flow (CBF) and provides an immediate postexercise executive function (EF) benefit. To our knowledge, no work has examined for how long passive exercise benefits EF. Here, healthy young adults (N = 22; 7 female) used a cycle ergometer to complete three 20-min conditions: passive exercise (via mechanically driven flywheel), a traditional light intensity (37 W) “active” exercise condition (i.e., via volitional pedalling) and a non-exercise control condition. An estimate of CBF was obtained via transcranial Doppler ultrasound measurement of middle cerebral artery blood velocity (MCAv) and antisaccades (i.e., saccade mirror-symmetrical to a target) were completed prior to and immediately, 30- and 60-min following each condition to assess EF. Passive and active exercise increased MCAv; however, the increase was larger in the latter condition. In terms of antisaccades, passive and active exercise provided an immediate postexercise reaction time benefit. At the 30-min assessment, the benefit was observed for active but not passive exercise and neither produced a benefit at the 60-min assessment. Thus, passive exercise provided an evanescent EF “boost” and is a finding that may reflect a smaller cortical hemodynamic response.

Decision-making from temporally accumulated conflicting evidence: The more the merrier.

How do humans evaluate temporally accumulated discrete pieces of evidence and arrive at a decision despite the presence of conflicting evidence? In the present study, we showed human participants a sequential presentation of objects drawn from two novel object categories and asked them to decide whether a given presentation contained more objects from one or the other category. We found that both a more disparate ratio and greater numerosity of objects improved both reaction time (RT) and accuracy. The effect of numerosity was separate from ratio, where with a fixed object ratio, sequences with more total objects had lower RT and lower error rates than those with fewer total objects. We replicated these results across three experiments. Additionally, even with the total presentation duration equated and with the motor response assignment varied from trial to trial, an effect of numerosity was still found in RT. The same RT benefit was also present when objects were shown simultaneously, rather than sequentially. Together, these results showed that, for comparative numerosity judgment involving sequential displays, there was a benefit of numerosity, such that showing more objects independent of the object ratio and the total presentation time led to faster decision performance.

Shared and distinct structure-function substrates of heterogenous distractor suppression ability between high and low working memory capacity individuals

Salient stimuli can capture attention in a bottom-up manner; however, this attentional capture can be suppressed in a top-down manner. It has been shown that individuals with high working memory capacity (WMC) can suppress salient‑but-irrelevant distractors better than those with low WMC; however, neural substrates underlying this difference remain unclear. To examine this, participants with high or low WMC (high-/low-WMC, n = 44/44) performed a visual search task wherein a color singleton item served as a salient distractor, and underwent structural and resting-state functional magnetic resonance imaging scans. Behaviorally, the color singleton distractor generally reduced the reaction time (RT). This RT benefit (ΔRT) was higher in the high-WMC group relative to the low-WMC group, indicating the superior distractor suppression ability of the high-WMC group. Moreover, leveraging voxel-based morphometry analysis, gray matter morphology (volume and deformation) in the ventral attention network (VAN) was found to show the same, positive associations with ΔRT in both WMC groups. However, correlations of the opposite sign were found between ΔRT and gray matter morphology in the frontoparietal (FPN)/default mode network (DMN) in the two WMC groups. Furthermore, resting-state functional connectivity analysis centering on regions with a structural-behavioral relationship found that connections between the left orbital and right superior frontal gyrus (hubs of DMN and VAN, respectively) was correlated with ΔRT in the high-WMC group (but not in the low-WMC group). Collectively, our work present shared and distinct neuroanatomical substrates of distractor suppression in high- and low-WMC individuals. Furthermore, intrinsic connectivity of the brain network hubs in high-WMC individuals may account for their superior ability in suppressing salient distractors.

Benefits from negative templates in easy and difficult search depend on rapid distractor rejection and enhanced guidance

While most research on attentional templates focuses on how attention can be guided toward targets, a growing body of research has been examining our ability to guide attention away from distractors using negative templates. A recent report showed larger reaction time benefits from negative templates during a difficult search task compared to an easy search task. However, it remains unclear what shifts in attentional processing led to these differences in reaction time benefits. In the current study, we tested the predictions of enhanced guidance and rapid rejection as potential explanations for the differential impact of negative templates based on search difficulty. In Experiment 1, we replicated the larger benefits from negative templates in a within-subjects design. In Experiment 2, we use eye tracking to measure the proportion of fixations directed towards target-colored distractors as an index of enhanced guidance and the dwell time on distractors as a measure of rapid rejection. We found more attentional guidance from negative templates in the difficult search condition. In addition, we found larger benefits of rapid rejection from negative templates in the difficult search condition. While we typically focus on templates as a way of guiding attention, these results highlight another key role played by attentional templates: rapid distractor rejection.

The human cerebellum is essential for modulating perceptual sensitivity based on temporal expectations.

A functional benefit of attention is to proactively enhance perceptual sensitivity in space and time. Although attentional orienting has traditionally been associated with cortico-thalamic networks, recent evidence has shown that individuals with cerebellar degeneration (CD) show a reduced reaction time benefit from cues that enable temporal anticipation. The present study examined whether the cerebellum contributes to the proactive attentional modulation in time of perceptual sensitivity. We tested CD participants on a non-speeded, challenging perceptual discrimination task, asking if they benefit from temporal cues. Strikingly, the CD group showed no duration-specific perceptual sensitivity benefit when cued by repeated but aperiodic presentation of the target interval. In contrast, they performed similar to controls when cued by a rhythmic stream. This dissociation further specifies the functional domain of the cerebellum and establishes its role in the attentional adjustment of perceptual sensitivity in time in addition to its well-documented role in motor timing.

The Impact of a Walnut-Rich Breakfast on Cognitive Performance Throughout the Day in Healthy Young Adults

ObjectivesA healthy diet is essential for optimal brain health. A number of food bioactives have been linked to cognitive benefits, including phytonutrients and essential fatty acids. Here we investigated the benefits of a walnut-rich breakfast, which contained flavonoids and omega-3s, to see whether consumption of these bioactives might lead to significant cognitive improvements throughout the day. MethodsA double-blind, crossover intervention study compared the effects of a breakfast containing 50g walnuts, with a nut-free, macronutrient-matched control. Participants were 32 healthy, young adults aged 18 to 30. Cognition, mood, blood, and EEG measures were recorded at baseline and 2, 4, and 6 hours postprandially. Only the cognitive data are reported here. All cognitive data were analyzed using linear mixed modeling (LMM) with baseline performance included as a covariate. Bonferroni corrected pairwise comparisons were used to investigate significant treatment effects. ResultsCompared to the control breakfast, the walnuts elicited significantly faster reaction times throughout the day on tasks measuring inhibition and task switching aspects of executive function. Memory recall results were mixed; slightly worse performance was observed at 2 hours following the walnut breakfast, but this was later reversed with walnuts outperforming control at 6 hours. ConclusionsThe findings provide evidence for reaction time benefits following a walnut-rich breakfast, with effects lasting throughout the day. The results concur with previous literature that suggests executive function effects are commonly observed in young adults following flavonoid supplementation. The memory recall effect at the final time point is consistent with previously observed benefits for both omega-3 fatty acids and flavonoids and may indicate that walnuts offer neuroprotection following long periods of cognitive demand, or that memory benefits depend upon the slower absorption of omega-3s or the delayed appearance of flavonoid metabolites. Walnuts are therefore beneficial to cognitive function in young adults after only a single, acute intake, but further investigation of precise mechanisms is needed. Funding SourcesThe study was funded by the California Walnut Commission, USA and pre-registered at clinicaltrials.gov.

Late guidance resolves the search slope paradox in contextual cueing.

Visual search is facilitated by statistical learning of repeated search contexts, termed 'contextual cueing'. Repeated displays are thought to enhance attentional guidance, but this has been challenged by the absence of search-slope differences between repeated and novel displays. Here we use eye-tracking to resolve this paradox by calculating a measure of when during search the contextual cueing benefit emerges. In 24 human participants we observe typical reaction time and fixation count benefits for repeated contexts, but no slope differences between repeated and novel search contexts. Eye-tracking showed that the attentional guidance benefit emerged over time, occurring later for larger set sizes, and producing similar response time benefits for small and large set sizes. We argue that repeated and novel contexts have similar slopes because learning benefits are confined to target-adjacent regions of roughly equivalent area across set sizes. This finding rules out one of the strongest pieces of evidence against an attentional account of contextual cueing.

Acting and reacting: Is intentional binding due to sense of agency or to temporal expectancy?

Intentional Binding (IB) refers to the phenomenon that we perceive effects we caused by a voluntary action earlier compared to stimuli we did not cause by our action. Although IB has been investigated in numerous studies and is routinely employed as an implicit measure for Sense of Agency, its underlying mechanisms are not yet clear. We investigated whether IB is based on Sense of Agency or on temporal expectancy. To this end, we compared how delay duration (250 ms vs. 600 ms) and duration predictability (valid vs. invalid) influence IB regarding Sense of Agency, measured as agency judgment (AJ), and temporal expectancy, measured as reaction time benefit (RTB). Results pattern were quite similar for IB and AJ but different for IB and RTB: IB and AJ decreased for longer delay durations, whereas the RTB increased for longer delay durations. An additional interaction of delay duration and duration predictability was only significant for AJ and RTB. Yet, the interactional pattern of delay duration and duration predictability on AJ did not differ from the result pattern of IB. Overall, results indicate IB to be rather driven by Sense of Agency than by temporal expectancy. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

No evidence for an attentional bias towards implicit temporal regularities

Action and perception are optimized by exploiting temporal regularities, and it has been suggested that the attentional system prioritizes information that contains some form of structure. Indeed, Zhao, Al-Aidroos, and Turk-Browne (Psychological Science, 24(5), 667–677, 2013) found that attention was biased towards the location and low-level visual features of shapes that appeared with a regular order but were irrelevant for the main search task. Here, we investigate whether this bias also holds for irrelevant metrical temporal regularities. In six experiments, participants were asked to perform search tasks. In Experiments 1a–d, sequences of squares, each presented at one of four locations, appeared in between the search trials. Crucially, in one location, the square appeared with a regular rhythm, whereas the timing in the other locations was random. In Experiments 2a and 2b, a sequence of centrally presented colored circles was shown in between the search trials, of which one specific color appeared regularly. We expected that, if attention is automatically biased towards these temporal regularities, reaction times would be faster if the target matches the location (Experiments 1a–d) or color (Experiments 2a–b) of the regular stimulus. However, no reaction time benefit was observed for these targets, suggesting that there was no attentional bias towards the regularity. In addition, we found no evidence for attentional entrainment to the rhythmic stimulus. These results suggest that people do not use implicit rhythmic temporal regularities to guide their attention in the same way as they use order regularities.

Modeling implicit learning in a cross-modal audio-visual serial reaction time task

This study examined implicit learning in a cross-modal condition, where visual and auditory stimuli were presented in an alternating fashion. Each cross-modal transition occurred with a probability of 0.85, enabling participants to gain a reaction time benefit by learning the cross-modal predictive information between colors and tones. Motor responses were randomly remapped to ensure that pure perceptual learning took place. The effect for the implicit learning was extracted from the data by fitting five different models to the data, which was highly variable due to motor variability. To examine individual learning rates for stimulus types of different discriminability and modality, the models were fitted per stimulus type and individually for each participant. The model selection identified the model that included motor variability, surprise effects for deviants and a serial position for effect onset as the most explanatory (Akaike weight 0.87). Further, there was a significant global cross-modal implicit learning effect for predictable versus deviant transitions (40 ms reaction time difference, p < 0.004). The learning rates over time differed for both modality and the stimuli within modalities, although there was no correlation to global error rates or reaction time differences between the stimulus types. These results demonstrate a modeling method that is well suited to extract detailed information about the success of implicit learning from high variability data. It further shows a cross-modal implicit learning effect, which extends the understanding of the implicit learning system and highlights the possibility for information to be processed in a cross-modal representation without conscious processing.

Humans show a higher preference for stimuli that are predictive relative to those that are predictable.

Recent studies suggest that humans prefer information that is linked to the process of prediction. Yet it remains to be specified whether preference judgments are biased to information that can be predicted, or information that enables to predict. We here use a serial reaction time task to disentangle these two options. In a first learning phase, participants were exposed to a continuous stream of arbitrary shapes while performing a go/no-go task. Embedded in this stream were hidden pairs of go-stimuli (e.g., shape A was always followed by shape B). Data show faster reaction times to predictable shapes (i.e., shape B) as compared to random and predictive shapes (i.e., shape A), indicating that participants learned the regularities and anticipated upcoming information. Importantly, in a subsequent, unannounced forced-choice preference task, the shapes that were predictive of others were significantly more preferred over random shapes than shapes that could be predicted. Because both the reaction time benefit in the learning phase and the effect in the preference phase could be considered rather small, we studied the relation between both. Interestingly, the preference correlated with the reaction time benefit from the learning phase. A closer look at this correlation further suggested that the difference in preference was only observed when participants picked up the contingencies between predictive and predictable shapes. This study adds evidence to the idea that prediction processes are not only fundamental for cognition, but contribute to the way we evaluate our external world.

Both facilitatory and inhibitory impairments underlie age-related differences of proactive cognitive control across the adult lifespan

We investigated two components of proactive cognitive control, response facilitation and response inhibition, in an adult lifespan sample (N=544, age range=18–91years) by administering two response-preparation tasks: a procue task, primarily involving facilitation, and an anticue task, involving both facilitation and inhibition. Cues in both tasks corresponded with the index and middle fingers of either the left or right hand. After a random preparation interval (PI) of 100–850ms following the onset of the cue signal, a single-target stimulus indicated the required response. Where procues were spatially aligned with the two fingers of the responding hand, anticues consistently indicated the two fingers of the opposite hand, requiring a remapping of cue location and response hand. This remapping requires inhibition to suppress the automatic activation of the ipsilateral responses. Previous research revealed typical reaction time (RT) profiles for procues and anticues as a function of PI. Whereas procues generate RT benefits (relative to a neutral-cue condition) already at short PIs, which increase with longer PIs, anticues generate RT costs at short PIs and RT benefits at longer PIs. Our results showed that, in the anticue task, older participants needed more preparation time to turn RT costs into RT benefits than younger participants, revealing an age-related deficit of response inhibition. Moreover, in both tasks, older participants were less able to increase RT benefits with longer PIs, revealing a deficit of response facilitation. We conclude that both facilitatory and inhibitory impairments contribute to age-related deficiencies in proactive cognitive control.

A micro-initiator realized by in-situ synthesis of three-dimensional porous copper azide and its ignition performance

Assembly of micro-initiator has received great attention on its application in micro-electromechanical systems, especially the integration between hazardous energetic materials and micro-ignitor. A micro-initiator was developed by integrating copper azide (Cu(N3)2·CuN3) nanoenergetic materials with a Ni-Cr microbridge realized onto a silicon substrate. In this work, three-dimensional (3-D) porous Cu (PCu) was prepared by electrochemical deposition with hydrogen bubble method. Copper azide has been synthesized through an in-situ reaction of hydrazoic acid (HN3) with three-dimensional (3-D) porous Cu (PCu), which facilitated integration between copper azide and microignitor. The novel materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry (TG/DTA) and an electric spark tester JGY-50III, respectively. The electrical explosion performances and electrostatic sensitivity of the micro-initiator were investigated by high-speed photography and electrostatic sensitivity tester. SEM images show the additives in the electrolyte alter the morphology of PCu, however, copper azide possesses similar morphology. The effect of copper valence and reaction time on azide reaction were evaluated. The discharge energy at 50% of novel copper azide was 0.098mJ. XRD analyses show the oxidization of PCu and the growth of the reaction time benefit the generation of cupric azide (Cu(N3)2) in the azide reaction. Furthermore, the discharge energy at 50% of novel micro-initiator was 64mJ. The novel material is environmentally friendly and can be successfully ignited by the Ni-Cr microbridge, exhibiting a significant improvement in micro-initiator application and realizing integrated fabrication of micro electro mechanical system (MEMS).

Foresight beats hindsight: The neural correlates underlying motor preparation in the pro-/anti-cue paradigm.

BackgroundHuman motor behaviors are characterized by both, reactive and proactive mechanisms. Yet, studies investigating the neural correlates of motor behavior almost exclusively focused on reactive motor processes. Here, we employed the pro‐/anti‐cue motor preparation paradigm to systematically study proactive motor control in an imaging environment. In this paradigm, either pro‐ or anti‐cues are presented in a blocked design. Four fingers (two from each hand) are mapped onto four visual target locations. Visual targets require a speeded response by one corresponding finger, but, most importantly, they are preceded by visual cues that are congruent (“pro‐cue”), incongruent (“anti‐cue”), or neutral with respect to the responding hand. With short cue‐target intervals, congruence effects are based on automatic motor priming of the correct hand (in case of pro‐cues) or incorrect hand (in case of anti‐cues), generating, respectively, reaction time benefits or reaction time costs relative to the neutral‐cue. With longer cue‐target intervals, slower top‐down processes become effective, transforming early anti‐cue interference into late anti‐cue facilitation.MethodsWe adapted this paradigm to be compatible with neuroimaging, tested and validated it behaviorally—both inside and outside the imaging environment—and implemented it in a whole‐brain functional magnetic resonance imaging study.Results and ConclusionOur imaging results indicate that pro‐cues elicited much less neural activation than did anti‐cues, the latter recruiting well‐known cognitive top‐down networks related to attention, response inhibition, and error monitoring/signaling, thereby revealing high‐level influences on proactive motor processes.

P285 Using transcranial direct current stimulation (tDCS) as a fatigue countermeasure

Introduction Long periods of sustained wakefulness are common in certain professions such as medicine, transportation, and military operations. These professions also carry a high-level of risk when performance on the job is not at its best. Caffeine is a common countermeasure used to combat the degradations in performance due to sleep deprivation but the effects are short lasting. Therefore, it is necessary to investigate other forms of fatigue countermeasures. Objectives Previously, we found that transcranial direct current stimulation (tDCS) in the middle of the night (0400) during 26 h of sustained wakefulness provided a performance and mood benefit that lasted at least 6 h. Caffeine only provided 2 h of benefit. In this study, we examined the differences between stimulation early into the night shift (1800) versus in the middle of the night (0400) and the duration of benefit. These results were compared to a caffeine and control groups. Patients and methods Five groups of ten participants in each received either active tDCS and placebo gum at 1800, caffeine gum with sham tDCS at 1800, active tDCS and placebo gum at 0400, caffeine gum with sham tDCS at 0400, or sham tDCS with placebo gum at 1800 and 0400 during 36-h of sustained wakefulness. Participants completed a vigilance task, a working memory task, a psychomotor vigilance task (PVT), and a procedural game beginning at 1800 h and continued every two hours throughout the night until 1900 the next day. Results tDCS dosed at 1800 provided 24 h of improved reaction times compared to the control group. Caffeine produced faster reactions times also compared to the control group but for half the duration than the tDCS group. The tDCS group also had higher accuracy and lower lapses in attention than the control group throughout the vigil. Early administration also resulted in improved mood ratings for the tDCS group. When dosing at 0400, the tDCS group had similar reaction time and accuracy benefits as the group dosed at 1800. The 0400 dosing of tDCS also had higher accuracy than the control group throughout the rest of the vigil for the short-term memory task. Conclusions In conclusion, we believe tDCS could be a powerful fatigue countermeasure. The effects appear to be more beneficial than caffeine because they are longer lasting and mood remains more positive.

Does language help regularity learning? The influence of verbalizations on implicit sequential regularity learning and the emergence of explicit knowledge in children, younger and older adults.

This study aimed at investigating the ability to learn regularities across the life span and examine whether this learning process can be supported or hampered by verbalizations. For this purpose, children (aged 8-10 years) and younger (aged 19-30 years) and older (aged 70-80 years) adults took part in a sequence learning experiment. We found that verbalizing sequence-congruent information during learning is a powerful tool to generate explicit knowledge and it is especially helpful for younger adults. Although recent research suggests that implicit learning can be influenced by directing the participants' attention to relevant aspects of the task, verbalizations had a much weaker influence on implicit than explicit learning. Our results show that verbalizing during learning slows down reaction times (RTs) but does not influence the amount of implicit learning. Especially older adults were not able to overcome the cost of the dual-task situation. Younger adults, in contrast, show an initial dual-tasking cost that, in the case of a helpful verbalization, is overcome with practice and turns into a RT and learning benefit. However, when the verbalization is omitted this benefit is lost, that is, better implicit learning seems to be confined to situations in which the supporting verbalization is maintained. Additionally, we did not find reliable age differences in implicit learning in the no verbalization groups, which speaks in favor of age-invariant models of implicit learning across the life span. (PsycINFO Database Record

Taming the White Bear

Previous research indicates that prior information about a target feature, such as its color, can speed search. Can search also be speeded by knowing what a target will not look like? In the two experiments reported here, participants searched for target letters. Prior to viewing search displays, participants were prompted either with the color in which one or more nontarget letters would appear (ignore trials) or with no information about the search display (neutral trials). Critically, when participants were given one consistent color to ignore for the duration of the experiment, compared with when they were given no information, there was a cost in reaction time (RT) early in the experiment. However, after extended practice, RTs on ignore trials were significantly faster than RTs on neutral trials, which provides a novel demonstration that knowledge about nontargets can improve search performance for targets. When the to-be-ignored color changed from trial to trial, no RT benefit was observed.