Stroop interference, practice, and aging

We report two experiments that investigate practice effects on Stroop color-word interference in older and younger adults. Both experiments employed a computerized, single-item version of the Stroop task with a voice response, and both involved practice over hundreds of trials. Both experiments showed generally similar practice patterns, including a practice-related reduction in the size of the color-word interference effect. However, the older group continued to show a larger interference effect throughout practice. These findings indicate that older adults show the same trend in practice-related improvement on the Stroop task as younger adults.     

More than superstition: differential effects of featural heterogeneity and change on subitizing and counting

This study investigates the effects of item heterogeneity (differences in color and shape) and moment-to-moment feature change as it relates to the issue of whether subitizing and counting involve different processes. Participants enumerated displays of up to eight items that were either homogeneous or heterogeneous. In situations where the heterogeneous displays always had approximately half of the items of one type and half of the other, heterogeneity significantly sped enumeration in the counting range (6-8 items) and significantly slowed enumeration in the subitizing range (1-3 items), a dissociation that suggests that subitizing and counting involve different operations. Moment-to-moment feature change had no effect on subitizing. However, feature change slowed counting, but only when participants were enumerating heterogeneous items that were half of one type and half of the other, as might be expected if participants were using differences in features to select items by type.     

Cognitive control and word recognition speed influence the Stroop effect in bilinguals

Bilinguals have been shown to be less susceptible to Stroop interference in their first language than monolinguals, though the cause is currently being debated. In two experiments, we explored how cognitive control and word recognition contribute to the Stroop effect by contrasting cognitive control (via a Simon arrow task), word recognition speed (via a Chinese/English word recognition task) and Stroop susceptibility (via a verbal Stroop task) between proficient and non‐proficient Chinese–English bilinguals. Compared to non‐proficient bilinguals, proficient bilinguals showed better cognitive control at inhibiting irrelevant information, and they were slower at recognising Chinese words but quicker at recognising English words. Critically, we also showed that proficient bilinguals showed a smaller Stroop effect than non‐proficient bilinguals in Chinese but a comparable Stroop effect as non‐proficient bilinguals in English. The results cannot be accounted for by cognitive control or word recognition speed alone; instead, they are best accommodated by assuming that cognitive control and word recognition speed jointly determine the Stroop effect. Thus, we conclude that enhanced cognitive control and delayed word recognition combine to reduce Stroop effect in bilinguals as compared to monolinguals.     

What dot clusters and bar graphs reveal: subitizing is fast counting and subtraction

In two studies, we found that dot enumeration tasks resulted in shallow-sloped response time (RT) functions for displays of 1-4 dots and steep-sloped functions for displays of 5-8 dots, replicating results implicating subitizing and counting processes for low and high ranges of dots, respectively. Extracting number from a specific type of bar graph within the same numerical range produced a shallow-sloped but scallop-shaped RT function. Factor analysis confirmed two independent subranges for dots, but all bar graph values defined a unitary factor. Significantly, factor scores and asymmetries both showed correlations of bar graph recognition to dot subitizing but not to dot counting, strongly suggesting that subitizing was used in both enumeration of low numbers of dots and bar graph recognition. According to these results, subitizing appears to be a nonverbal process operating flexibly in either additive or subtractive fashion on analog quantities having spatial extent, a conclusion consistent with a fast-counting model of subitizing but not with other models of the subitizing process.     

Subitizing and counting depend on different attentional mechanisms: Evidence from visual enumeration in afterimages

Two experiments showed that, when selective eye movements were disabled by the presentation of stimuli in the form of afterimages, increased inspection time and facilitative stimulus configurations failed to increase the subitizing limit of 4 objects. Afterimages of two to eight dots induced by a photographic flashgun were shown to 3 adult subjects. For more than 4 objects, enumeration errors occurred at a rate of 20%–30%. Enumeration was effectively perfect for 2–4 linearly configured dots, with occasional errors surprisingly occurring in that range when dots appeared in groups of up to 3 items. No errors occurred in nonafterimage control conditions. Enumeration errors were attributed to failures of individuating dots to be counted due to the deactivation of selective eye movements in afterimages. A third experiment supported this interpretation by disabling eye movements with briefly presented stimuli and producing results much like those of the afterimage conditions.     

Trading accuracy for speed: gender differences on a Stroop task under mild performance anxiety.

A standard Stroop task was used to examine the effect of performance anxiety on 58 male and 69 female undergraduates. Subjects were approached either by two casually dressed experimenters who did not stress speed or accuracy or by 4 or 5 formally dressed experimenters who stressed quick and accurate performance. Subjects were told the test would assess their "mental acuity"; their responses were visibly tape-recorded. Reaction times did not show differential response by anxiety condition; men and women showed different RTs only in the low-anxiety condition, with women performing significantly more slowly. There were no significant differences for the high-anxiety condition. Analysis of errors showed women were more accurate than men. Men traded accuracy for speed and may have been under equal performance stress in both situations. When performance was not stressed, women were slower and more accurate than men. When performance was stressed, women increased their speed to match that of men while maintaining their greater accuracy.     

The role of working memory in spatial enumeration: Patterns of selective interference in subitizing and counting

Articulatory suppression (repeatedly pronouncing a syllable or word while carrying out another task) is thought to interfere selectively with the phonological store in working memory (Larsen & Baddeley, 2003). Although suppression interferes with temporal enumeration (enumerating successive light flashes), to date there has been little evidence of such interference in spatial enumeration (enumerating units laid out in space at one time)—a finding with serious ramifications for theories of enumeration. Participants carried out a spatial enumeration task, enumerating 1–8 dots while listening to a metronome (baseline condition) or while carrying out a secondary task to the rhythm of the metronome (dual-task condition). There were four secondary tasks: simple articulation (saying a letter), complex articulation (alternating between two letters), simple tapping (tapping a finger), and complex tapping (alternating between two fingers). Interference varied with number of items, but the pattern differed from that observed with temporal enumeration (Logie & Baddeley, 1987).     

A reversal of the Stroop interference effect,through scanning:

Interference on the Stroop test has been explained on the basis of a stronger habit (word reading) interfering with a weaker one (color naming) on an incongruous color-word (CW) card. Since scanning for words is slower (weaker) than scanning for colors, it was predicted that making the Stroop a scanning task would produce more interference with scanning for words rather than colors on the CW card. This prediction was confirmed. In addition, analyses of individual differences offered some support for differential habit-strength theories of Stroop interference. However, differences between the standard and scanning Stroop tests suggested that some kind of information-processing analysis would be more fruitful.     

Numerical acuity of fish is improved in the presence of moving targets,but only in the subitizing range

There is controversy in comparative psychology about whether on the one hand non-symbolic number estimation of small (≤4) and large numbers involves a single mechanism (an approximate number system), or whether on the other hand enumeration of the numbers 1–4 is accomplished by a separate mechanism, an object tracking system. To date, support for the latter hypothesis has come only from the different ratio-dependency of performance seen in the two numerical ranges, a reading that has been criticized on several grounds. In humans, the two-system hypothesis is supported by evidence showing that manipulation of the physical properties of the stimuli (e.g., the motion of the items) has dissimilar effects on small- and large-number discrimination. In this research, we studied this effect on guppies. Initially, fish were trained to simultaneously discriminate two numerical contrasts having the same easy ratio (0.50): one in the small-number (2 vs. 4) range and one in the large-number (6 vs. 12) range. Half of the fish were presented with moving items; the other half were shown the same stimuli without motion. Fish were then subjected to non-reinforced probe trials in the presence of a more difficult ratio (0.75: 3 vs. 4 and 9 vs. 12). Under both static and moving conditions, the fish significantly discriminated 6 versus 12, but not 9 versus 12 items. As regards small numbers, both groups learned to discriminate a 0.50 ratio, but only fish tested with moving stimuli also discriminated 3 and 4 items. This differential effect suggests that fish may possess two separate systems for small- and large-number discrimination.     

Self-monitoring,need for cognition,and the Stroop effect: a preliminary study

The color-word Stroop task requires an individual to ignore one piece of information (word) while responding to another (color). Since self-monitors are good at adapting their responses to fit a situation and those high in need for cognition carefully think through information before responding, this study explored the relationship between self-monitoring and need for cognition using Stroop interference. It was anticipated that self-monitoring would reduce Stroop interference, while need for cognition would increase Stroop interference. 23 General Psychology students (10 men, 13 women, M(age) = 18.8 yr.) participated. Participants were given the Self-monitoring Scale, the Need for Cognition Scale, and the Stroop Color-Word Test. Analysis indicated that Need for Cognition was not correlated with Stroop interference (r = .31) but higher scores on Self-monitoring were correlated with lower Stroop interference (r = .43). Implications for research are suggested.     

Adult age differences in the speed and capacity of information processing: 2. An electrophysiological approach

A total of 60 subjects performed different variants of the Sternberg memory search task in an experiment designed to evaluate aging differences in the speed of the human information-processing system. The present study examined the nature of the age-related slowing using convergent methodologies of Sternberg's additive factors logic, the speed-accuracy trade-off, and the P300 component of the event-related brain potential. These methodologies revealed that a substantial component of slowing was manifest in perceptual encoding, response criterion adjustment, and response execution, with a lesser component related to memory search speed.     

Unconsciously controlled processing: the Stroop effect reconsidered

The Stroop effect is widely considered to be compelling evidence that an acquired skill such as reading is “automatic” in the sense that lexical/semantic analyses of single words cannot be prevented, even when they are irrelevant and harmful to the task at hand. This view is challenged by a series of three experiments in which the presence/absence of a Stroop effect depends on (1) whether all of the target elements are colored or not, in conjunction with (2) whether the target and the spatially distinct color word distractor belong to the same domain or not. A framework is offered in which domain-specific encoding algorithms play a major role. Skilled word recognition is typically unconscious, but is characterized better as contextually controlled, rather than “automatic.”     

The effect of aging in recollective experience: the processing speed and executive functioning hypothesis

This study was designed to investigate the effects of aging on consciousness in recognition memory, using the Remember/Know/Guess procedure (Gardiner, J. M., & Richarson-Klavehn, A. (2000). Remembering and Knowing. In E. Tulving & F. I. M. Craik (Eds.), The Oxford Handbook of Memory. Oxford University Press.). In recognition memory, older participants report fewer occasions on which recognition is accompanied by recollection of the original encoding context. Two main hypotheses were tested: the speed mediation hypothesis (Salthouse, T. A. (1996). The processing-speed theory of adult age differences in cognition. Psychological Review, 3, 403–428) and the executive-aging hypothesis (West, R. L. (1996). An application of prefrontal cortex function theory to cognitive aging. Psychological Bulletin, 120, 272–292). A group of young and a group of older adults took a recognition test in which they classified their responses according to Gardiner, J. M., & Richarson-Klavehn, A. (2000). Remembering and Knowing. In E. Tulving & F. I. M. Craik (Eds.), The Oxford Handbook of Memory. Oxford University Press. remember-know-guess paradigm. Subsequently, participants completed processing speed and executive function tests. The results showed that among the older participants, R responses decreased, but K responses did not. Moreover, a hierarchical regression analysis supported the view that the effect of age in recollection experience is determined by frontal lobe integrity and not by diminution of processing speed.     

Mobile Internet Testing: An analysis of equivalence,individual differences,and reactions

Mobile internet testing (MIT) is the latest cost effective technological push in employment testing. The ability to access assessments via the internet using mobile devices provides increased speed and convenience for both administrators and respondents. In this article, we examine the equivalence of MIT compared with testing on personal computers (PCs) and whether attitudes and other individual differences influence responses and reactions to MIT. Results demonstrated equivalence for a supervisory situational judgment test across testing modes, but not for a cognitive ability test. Significant relationships were found between anxiety and both performance and reactions to mobile assessment. Respondents also reported significantly more positive reactions when tested on a PC versus a mobile device. Future research and practical implications are discussed.     

Individual differences in Stroop dilution: tests of the attention-capture hypothesis.

Kahneman and Chajczyk (1983) found that naming a colored bar was slowed when a color word was nearby but that this decrement was reduced when a neutral word was also present. This has been referred to as the dilution effect. They accounted for their results with an attention-capture hypothesis. Response time distributions to stimuli that contained a color word and a neutral word within individuals were examined. The dilution effect did not appear within individuals. Some individuals exhibited strong Stroop interference effects, whereas others exhibited no interference. Experiment 2 showed that the interference pattern within individuals was consistent across days. Experiment 3 showed that performance could not be explained by a selection strategy that was based on word length. These experiments showed that performance in a color-plus-neutral word condition reflects a systematic pattern of interference or noninterference that varies across individuals.     

An auditory Stroop effect for pitch, loudness, and time

Increased reaction time to pitch, loudness, or duration of an auditorily presented word whose meaning is in conflict with the response label (i.e., high/low, loud/soft, or fast/slow) demonstrates an auditory Stroop effect. Fifteen normal adults participated in an auditory Stroop test. Analysis of reaction time data supports the existence of an auditory Stroop effect for pitch and loudness, but not duration. The interaction between psychoacoustic and semantic attributes of speech stimuli is discussed.     

Context-specific control and the Stroop negative priming effect

The present study highlights the utility of context-specific learning for different probe types in accounting for the commonly observed dependence of negative priming on probe selection. Using a Stroop priming procedure, Experiments 1a and 1b offered a demonstration that Stroop priming effects can differ qualitatively for selection and no-selection probes when probe selection is manipulated between subjects, but not when it is manipulated randomly from trial to trial within subject (see also Moore, 1994). In Experiments 2 and 3, selection and no-selection probes served as two contexts that varied randomly from trial to trial, but for which proportion repeated was manipulated separately. A context-specific proportion repeated effect was observed in Experiment 2, characterized by modest quantitative shifts in the repetition effects as a function of the context-specific proportion repeated manipulation. However, with a longer intertrial interval in Experiment 3, a context-specific proportion repeated manipulation that focused on the no-selection probes changed the repetition effect qualitatively, from negative priming when the proportion repeated was .25 to positive priming when the proportion repeated was .75. The results are discussed with reference to the role of rapid, context-specific learning processes in the integration of prior experiences with current perception and action.     

The Stroop effect in English-Japanese bilinguals: the effect of phonological similarity

English-Japanese bilinguals performed a Stroop color-word interference task with both English and Japanese stimuli and responded in both English and Japanese. The Japanese stimuli were either the traditional color terms (TCTs) written in Hiragana or loanwords (LWs) from English written in Katakana. Both within-language and between-language interference were found for all combinations of stimuli and responses. The between-language interference was larger for Katakana LWs (phonologically similar to English) than for Hiragana TCTs, especially with Japanese responses. The magnitude of this phonological effect increased with self-rated reading fluency in Japanese. Overall responding was slower and the Stroop effect larger with English than with Japanese stimuli. These results suggest that unintentional lexical access elicits automatic phonological processing even with intermediate-level reading proficiency.