Delta Plot Analyses Research Articles

Semantic Stroop interference is modulated by the availability of executive resources: Insights from delta-plot analyses and cognitive load manipulation

We investigated whether, during visual word recognition, semantic processing is modulated by attentional control mechanisms directed at matching semantic information with task-relevant goals. In previous research, we analyzed the semantic Stroop interference as a function of response latency (delta-plot analyses) and found that this phenomenon mainly occurs in the slowest responses. Here, we investigated whether this pattern is due to reduced ability to proactively maintain the task goal in these slowest trials. In two pairs of experiments, participants completed two semantic Stroop tasks: a classic semantic Stroop task (Experiment 1A and 2A) and a semantic Stroop task combined with an n-back task (Experiment 1B and 2B). The two pairs of experiments only differed in the trial pace, which was slightly faster in Experiments 2A and 2B than in Experiments 1A and 1B. By taxing the executive control system, the n-back task was expected to hinder proactive control. Delta-plot analyses of the semantic Stroop task replicated the enhanced effect in the slowest responses, but only under sufficient time pressure. Combining the semantic Stroop task with the n-back task produced a change in the distributional profile of semantic Stroop interference, which we ascribe to a general difficulty in the use of proactive control. Our findings suggest that semantic Stroop interference is, to some extent, dependent on the available executive resources, while also being sensitive to subtle variations in task conditions.

GABAergic Involvement in Selective Attention.

Animals need to cope with abundant sensory information, and one strategy is to selectively direct attention to only the most relevant part of the environment. Although the cortical networks of selective attention have been studied extensively, its underlying neurotransmitter systems, especially the role of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA), remain less well understood. Increased GABAA receptor activity because of administration of benzodiazepines such as lorazepam is known to slow reactions in cognitive tasks. However, there is limited knowledge about GABAergic involvement in selective attention. Particularly, it is unknown whether increased GABAA receptor activity slows the build-up of selectivity or generally widens attentional focus. To address this question, participants (n = 29) received 1 mg lorazepam and placebo (within-subjects, double-blind) and performed an extended version of the flanker task. The spatial distribution of selective attention was studied by systematically manipulating number and position of incongruent flankers; the temporal build-up was characterized using delta plots. An online task version was presented to an independent, unmedicated sample (n = 25) to verify task effects. Under placebo and in the unmedicated sample, only the number of incongruent flankers, but not their position, influenced RTs. Incongruent flankers impaired RTs more strongly under lorazepam than placebo, especially when adjacent to the target. Delta plot analyses of RT showed that this effect persisted even when participants reacted slowly, indicating that lorazepam-induced impairments in selective attention do not result from simply slowed down build-up of selectivity. Instead, our data indicate that increased GABAA receptor activity widens the attentional focus.

The role of temporal order of relevant and irrelevant dimensions within conflict tasks.

Conflict tasks are commonly used to investigate control processes under situations of relevant and irrelevant sources of information. In addition to compatibility effects at a mean behavioral level, delta plot analyses of reaction time distributions reveal that the compatibility effect generally increases with time (i.e., positive delta plot slopes) across most conflict-like tasks. Critically, the underlying causes of the increasing delta plot slopes with different types of distractors are still poorly understood. The present study tested whether the relative onset of target-to-distractor processing affects the delta plot slope. Specifically, we manipulated the temporal order of relevant and irrelevant dimensions within an Eriksen flanker task (Experiment [Exp.] 1), an Arrow-Simon task (Exp. 2), and a manual Stroop task (Exp. 3a/3b). The results of the Eriksen flanker task and Arrow-Simon task revealed that the delta plots slopes were less increasing (and instead rather decreasing) when the irrelevant dimension appears first (IR condition) compared to the reversed order (RI condition)-consistent with the idea that the underlying mechanism driving the slope of the delta plot is the temporal overlap of activation between the relevant and irrelevant dimensions. In contrast, for the Stroop task, the delta plots in the RI condition were not more increasing than the ones for the IR condition. Overall, these results suggest that the temporal properties strongly influence delta plot shape, but that the temporal dynamics operating in the flanker task and the Arrow-Simon task differs from the Stroop task, at least under conditions where relevant and irrelevant information is presented sequentially. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Distributional analyses reveal the individual differences in congruency sequence effect.

As a sequential modulation of conflict, congruency sequence effect indexes a conflict-induced performance improvement, which is observed as reduced congruency effects for trials after the incongruent trials than for trials after the congruent trials. Although congruency sequence effect has been investigated widely in healthy humans, the studies of distributional characteristics across prototypical congruency tasks are scarce. To investigate this issue, the present study adopts the between-subjects design to carry out three experiments, where subjects were separately informed to perform the Stroop, word Flanker, and letter Flanker tasks. The results showed that congruency sequence effect occurred in the congruent and incongruent trials in the Stroop and word Flanker tasks, respectively, and absented in the letter Flanker task, which is interpreted as the differences in the nature and difficulty of the tasks. The distributional properties of congruency sequence effect did not significantly differ from the Gaussian distribution in the Stroop and word Flanker tasks, but not in the letter Flanker task, suggesting the inter-individual variability of congruency sequence effect depends on the nature of tasks. Importantly, the delta plot analyses showed pronouncedly increased congruency sequence effect over the slowest percentile bines in both the Stroop and word Flanker tasks, verifying the activation suppression hypothesis. Altogether, the present study enriches the literature on the distributional characteristics of congruency sequence effect.

Prepotent task-irrelevant semantic information is dampened by domain-specific control mechanisms during visual word recognition.

We investigated whether semantic interference occurring during visual word recognition is resolved using domain-general control mechanisms or using more specific mechanisms related to semantic processing. We asked participants to perform a lexical decision task with taboo stimuli, which induce semantic interference, as well as a semantic Stroop task and a Simon task, intended as benchmarks of linguistic-semantic and non-linguistic interference, respectively. Using a correlational approach, we investigated potential similarities between effects produced in the three tasks, both at the level of overall means and as a function of response speed (delta-plot analysis). Correlations selectively surfaced between the lexical decision and the semantic Stroop task. These findings suggest that, during visual word recognition, semantic interference is controlled by semantic-specific mechanisms, which intervene to face prepotent but task-irrelevant semantic information interfering with the accomplishment of the task's goal.

Cognitive control of action naming in adults who stutter

PurposeBased on previous evidence that cognitive control of lexical selection in object (noun) naming operates differently in adults who stutter (AWS) versus typically-fluent adults (TFA), the aim was to investigate cognitive control of lexical selection in action (verb) naming in AWS. Method12 AWS and 12 TFA named line drawings depicting actions using verbs. Half of the pictures had high-agreement action names and the other half low-agreement action names. Naming accuracy and reaction times (RT), and event-related potentials (ERPs) time-locked to picture onset, were compared between groups. ResultsNaming RTs were slower for low- versus high-agreement trials, and the magnitude of this effect was larger in AWS versus TFA. Delta-plot analysis of naming RTs revealed that individual differences in selective inhibition were associated with the agreement effect on naming RTs in AWS but not TFA. Action naming elicited frontal-central N2 activity in both agreement conditions in TFA but not AWS. Additionally, a later, posterior P3b component was affected by agreement in TFA only. In AWS, low-agreement action naming elicited frontal P3a activation. ConclusionsResults suggest that cognitive control of action name selection was qualitatively different between groups. In TFA, cognitive control of lexical selection in action naming involved nonselective inhibition, as well as more efficient working memory updating on high- versus low-agreement trials. In AWS, cognitive control of low-agreement action naming involved increased focal attention. Individual differences in selective inhibition may have moderated cognitive control of action naming in AWS.

Eriksen flanker delta plot shapes depend on the stimulus.

Several experimental paradigms are purported to measure response conflict, including the Stroop, Simon, and Eriksen flanker tasks. Although these tasks are often treated as being similar, delta plot analyses of response time distributions have revealed marked differences across them. Several theories have been proposed to explain these differences, however, assessing their veracity is difficult given the numerous differences across tasks. To explore what might cause delta plots to differ in a more controlled manner, here stimulus materials were manipulated across four Eriksen flanker tasks. The results reveal substantially different delta plot shapes for different stimuli: positive-going functions when color or motion served as the target and flankers, and delta plots with negative-going components when stimuli were arrows or orientated gratings. These results cast doubt on the proposal that negative-going delta plots occur only when spatial location serves as the interfering stimulus dimension. Moreover, because targets and flankers were always of the same stimulus type, the results also suggest that differences in materials across the relevant and irrelevant dimensions do not determine delta plot shapes. Instead, we propose that the delta plot shape is determined by several factors, including how early the interfering information is processed in the visual cortex.

Inhibitory Control of Lexical Selection in Adults who Stutter

PurposeBased on previous evidence that lexical selection may operate differently in adults who stutter (AWS) versus typically-fluent adults (TFA), and that atypical attentional processing may be a contributing factor, the purpose of this study was to investigate inhibitory control of lexical selection in AWS. Method12 AWS and 12 TFA completed two tasks. One was a picture naming task featuring High and Low Agreement object naming. Naming accuracy and reaction times (RT), and event-related potentials (ERPs) time-locked to picture onset, were recorded. Second was a flanker task featuring Congruent and Incongruent arrow arrays. Push-button accuracy and RTs, and ERPs time-locked to arrow array onset, were recorded. ResultsLow Agreement pictures were named less accurately and slower than High Agreement pictures in both Groups. The magnitude of the Agreement effect on naming RTs was larger in AWS versus TFA. Delta-plot analysis revealed that the Agreement effect was positively correlated with individual differences in inhibition in TFA but not in AWS. Moreover, Low Agreement pictures elicited negative-going ERP activity relative to High Agreement pictures in both Groups. However, the scalp topography of this effect was markedly reduced in AWS versus TFA. For the Flanker task, Congruency affected push-button accuracy and RTs, and N2 amplitudes, similarly between groups. ConclusionsResults point to a selective deficit in inhibitory control of lexical selection in AWS. Potential pathways between diminished inhibitory control of lexical selection, speech motor control and stuttering are discussed.

Delta plot analysis of cardiovascular and cardiorespiratory interactions in young women with orthostatic intolerance

ObjectiveTemporal dynamics of cardiovascular and cardiorespiratory interactions during a head-up tilt test (HUTT) were investigated using a new method called delta plot analysis (DPA) that deals with the intrinsic nonstationarity feature of time series. MethodsTwenty-one young female patients (28 ± 7 years) with orthostatic intolerance (OI) and 13 age-matched female controls (26 ± 5 years) were investigated during a 70° HUTT. Analyses were performed on bivariate time series including beat-to-beat intervals (BBI), respiratory amplitude (RESP) at BBI onset as well as systolic (SYS) and diastolic (DIA) blood pressure at simultaneous and shifted beats. DPA was used to characterize cardiovascular interactions as SYS→BBI and BBI→DIA, as well as cardiorespiratory interactions as RESP→BBI and RESP→DIA. ResultsOccurrence of simultaneous BBI increases due to SYS increases (bradycardic baroreflex) was significantly reduced during orthostatic phase in patients (28.54 ± 6.32% versus 36.35 ± 4.77%, p < 0.01). Considering the magnitude of consecutive changes, patients revealed an increased amount of points characterized by low heart rate variability combined with high blood pressure variability for SYS→BBI at tau = 0, BBI→SYS at tau = 2 and BBI→DIA at tau = 1. Interaction analysis for SYS→BBI showed highly significant differences already in supine position (10.08±5.90% versus 4.78±2.42%, p < 0.01), during tilt-up (12.32±5.00% versus 5.51±3.07%, p < 0.0001) and during early orthostatic phase (14.55±6.00% versus 5.71±3.14%, p < 0.001). ConclusionTemporal dynamic analysis by DPA revealed impaired autonomic control in patients compared to healthy subjects during supine position, transition and orthostatic phase. SignificanceDPA is a promising graphical tool to demonstrate impaired autonomic regulation.

Beyond mean reaction times: Combining distributional analyses with processing stage manipulations in the Simon task

We combined analyses of reaction time (RT) distributions with experimental manipulations of different processing stages (perception, decision, motor execution) in a Simon task to investigate which changes in Simon effects could be explained entirely by fading irrelevant response activation. Consistent with fading activation accounts, the Simon effect on mean RT was usually smaller for conditions with slower responses (Expts. 1–3 but not Expt. 4), and delta plot analyses revealed that it was always smaller for the slower responses within each condition. Critically, however, these analyses also revealed that some experimental manipulations produced upward or downward shifts in the RT delta plots, thus altering the Simon effect on mean RT in ways that could not be explained by fading activation. The results demonstrate the power of combining RT distributional analyses with experimental manipulations to reveal mechanisms contributing to the Simon effect that would not be revealed using only mean RT. We consider alternatives to fading activation accounts of decreasing delta plots and discuss the contribution of different cognitive stages in modulating Simon effects.

Delta plots do not reveal response inhibition in lying.

The role of response inhibition in lying is debated. By using the delta-plot method applied to the Sheffield Lie Test, Debey, Ridderinkhof, De Houwer, De Schryver, and Verschuere (2015) provided evidence supporting the role of inhibition in lying. In the study of Debey et al., inhibitory skill was measured in terms of the size of the lie effect. However, to provide convincing evidence that delta plots highlight the role of response inhibition in lying, inhibitory ability must be evaluated independently from the size of the lie effect. After replicating original findings, this article shows that a delta plot analysis does not differentiate individuals with different inhibitory abilities, when inhibitory skill is measured by means of the Stop Signal Task, instead of the size of the lie effect. This suggests that researchers should be cautious when making conclusions about cognitive mechanisms based on the sole analysis of delta plots.

Electrophysiological evidence that inhibition supports lexical selection in picture naming

We investigated the neural basis of inhibitory control during lexical selection. Participants overtly named pictures while response times (RTs) and event-related brain potentials (ERPs) were recorded. The difficulty of lexical selection was manipulated by using object and action pictures with high name agreement (few response candidates) versus low name agreement (many response candidates). To assess the involvement of inhibition, we conducted delta plot analyses of naming RTs and examined the N2 component of the ERP. We found longer mean naming RTs and a larger N2 amplitude in the low relative to the high name agreement condition. For action naming we found a negative correlation between the slopes of the slowest delta segment and the difference in N2 amplitude between the low and high name agreement conditions. The converging behavioral and electrophysiological evidence suggests that selective inhibition is engaged to reduce competition during lexical selection in picture naming.

Selective and nonselective inhibition of competitors in picture naming

The present study examined the relation between nonselective inhibition and selective inhibition in picture naming performance. Nonselective inhibition refers to the ability to suppress any unwanted response, whereas selective inhibition refers to the ability to suppress specific competing responses. The degree of competition in picture naming was manipulated by presenting targets along with distractor words that could be semantically related (e.g., a picture of a dog combined with the word cat) or unrelated (tree) to the picture name. The mean naming response time (RT) was longer in the related than in the unrelated condition, reflecting semantic interference. Delta plot analyses showed that participants with small mean semantic interference effects employed selective inhibition more effectively than did participants with larger semantic interference effects. The participants were also tested on the stop-signal task, which taps nonselective inhibition. Their performance on this task was correlated with their mean naming RT but, importantly, not with the selective inhibition indexed by the delta plot analyses and the magnitude of the semantic interference effect. These results indicate that nonselective inhibition ability and selective inhibition of competitors in picture naming are separable to some extent.

Attentional Inhibition in Bilingual Naming Performance: Evidence from Delta-Plot Analyses

It has been argued that inhibition is a mechanism of attentional control in bilingual language performance. Evidence suggests that effects of inhibition are largest in the tail of a response time (RT) distribution in non-linguistic and monolingual performance domains. We examined this for bilingual performance by conducting delta-plot analyses of naming RTs. Dutch–English bilingual speakers named pictures using English while trying to ignore superimposed neutral Xs or Dutch distractor words that were semantically related, unrelated, or translations. The mean RTs revealed semantic, translation, and lexicality effects. The delta plots leveled off with increasing RT, more so when the mean distractor effect was smaller as compared with larger. This suggests that the influence of inhibition is largest toward the distribution tail, corresponding to what is observed in other performance domains. Moreover, the delta plots suggested that more inhibition was applied by high- than low-proficiency individuals in the unrelated than the other distractor conditions. These results support the view that inhibition is a domain-general mechanism that may be optionally engaged depending on the prevailing circumstances.

Abstract LB-31: Drug combination studies: theory and analysis

Abstract A novel method for the graphical analysis of drug combination studies is presented. This method, Delta Plot Analysis, addresses the shortcomings of Isobolograms and Combination Index determinations. By use of this method, one may choose either a Bliss Independence or Loewe Additivity model and conduct the analysis. The method is comparative in nature, plotted as a function of cell survival (tracking other observables is also possible), and most importantly contains confidence intervals for determining significance above/below an additive effect line. In short, assay data with much scatter require greater differentiation from additivity to be interpreted as anything other than additive while data with less scatter allow one to conclude synergy or antagonism with less deviation from theoretical additive. Notably, the method handles partial response curves and makes use of single agent dose response curves to incorporate experimental uncertainty. A great advantage of the method is that synergistic and antagonistic interactions produce signature patterns in addition to providing data points falling outside of the additive effect confidence interval - something of great utility to the analyst. Also intriguingly, when accounting for experimental uncertainty (through simulations or with empirical data), a synergistic interaction is revealed to be synergistic regardless of the choice of Bliss or Loewe models. Delta Plot Analysis has been validated with published data and confirmed with in-house drug combination studies. The method is robust, requires no specialized software and easily depicts a multidrug combination study. This presentation also includes a look at the theory behind multiple drug interactions from a first principles perspective and provides a useful way of connecting drug action with drug effect. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-31.

Specific effects of acute moderate exercise on cognitive control

The main issue of this study was to determine whether cognitive control is affected by acute moderate exercise. Twelve participants [4 females (VO 2 max = 42 ml/kg/min) and 8 males (VO 2 max = 48 ml/kg/min)] performed a Simon task while cycling at a carefully controlled workload intensity corresponding to their individual ventilatory threshold. The distribution-analytical technique and the delta plot analysis [Ridderinkhof, K. R. (2002). Activation and suppression in conflict tasks: Empirical clarification through distributional analyses. In W. Prinz & B. Hommel (Eds.), Common mechanisms in perception and action. Attention and performance (Vol. 19, pp. 494–519). Oxford: Oxford University Press.] were used to assess the role of selective response inhibition in resolving response conflict. Results showed that cognitive processes appeared to be differently affected by acute moderate exercise. Reaction time results confirmed that performance is better (faster without change in accuracy) when the cognitive task is performed simultaneously with exercise. Between-trial adjustments (post-conflict and post-error) highlighted that cognitive control adjustments are also fully efficient during exercise. However, the effect of congruency (Simon effect) appeared to be more pronounced during exercise compared to rest which suggests that the response inhibition is deteriorated during exercise. The present findings suggest that acute moderate exercise differently affects some specific aspects of cognitive functions.

Delta Plots in the Study of Individual Differences: New Tools Reveal Response Inhibition Deficits in AD/HD That Are Eliminated by Methylphenidate Treatment.

The authors highlight the utility of distribution-analytical techniques in the study of individual differences and clinical disorders. Cognitive deficits associated with attention-deficit/hyperactivity disorder (AD/HD) were examined by using delta-plot analyses of performance data (reaction time and accuracy) obtained through the use of a prototypical conflict task, the Eriksen flanker task. In 20 children with AD/HD (compared with matched control participants), overall performance measures indicated a marginal performance deficit. Delta-plot analyses indicated that performance deficits associated with AD/HD involve response inhibition but not automatic response activation. In a within-subjects titration study, the response inhibition deficit was eliminated by methylphenidate treatment, but these effects were highly dose specific. The beneficial effect of methylphenidate was clarified further after correcting for inter-individual variation in sensitivity to medicine dosage.

Ecocultural bias in culture-specific intelligence tests in an ecologically diverse culture: The Philippines

In an ecologically diverse society (the Philippines), measurement equivalence across ecological settings was investigated with two culture-specific intelligence tests. Comparative reliability and factor analyses indicated that the tests (one for preschoolers, one for adults) were measuring the same ability dimensions equally reliably within each setting. Across settings, however, delta-plot analyses revealed considerable bias at the item level in tests of crystallized abilities, and the preschool tests tended to favor children from the setting where the tests were developed. The results are interpreted in terms of an ecocultural framework in which group differences in intellectual performance can reflect not only actual ability differences but differences in practice with, and exposure to, particular environmental stimuli and/or cognitive skills. The study demonstrates: (a) the need, particularly in ecologically diverse and segmented societies, to inspect tests for item bias; (b) the difficulty of culturally “equating” cognitive measures, even for very similar cultural subgroups who differ primarily in ecological setting.