Can the Stroop effect serve as the gold standard of conflict monitoring and control? A conceptual critique.

The Stroop effect has been a key to the assay of selective attention since the time of the epoch-making study by J.R. Stroop almost a century ago. However, recent work based on computational modeling and recording of brain activations ignored the primary meaning of the Stroop effect as a measure of selectivity-with the Stroop test losing its raison d'être. Espousing the new framework, numerous studies in the past 20 years conceived performance in the Stroop task in terms of conflict-induced adjustments governed by central control on a trial-to-trial basis. In the face of this tsunami, we try to convince the reader that the Stroop effect cannot serve as a testing ground for conflict-monitoring and control, because these constructs are fundamentally unsuited to serve as a candidate theory of Stroop processes. A range of problems are discussed that singly and collectively pose grave doubts regarding the validity of a control and conflict monitoring account in the Stroop domain. We show how the key notion of conflict is misconstrued in conflict-monitoring models. Due to space limitations and for sake of wider accessibility, our treatment here cannot be technical.

Preparing for the Worst: Attention is Enhanced Prior to Any Upcoming Emotional or Neutral Stimulus.

Do people allocate more or fewer attentional resources when preparing for negative emotional visual stimuli to appear? In three experiments (total N = 150), participants performed a change-detection task while expecting a neutral, threatening, disgusting, or joyful stimulus or no stimulus to appear at a fixed moment. Responses to an infrequent dot probe were faster when participants were expecting a distracting stimulus. Importantly, although only negative stimuli impaired change-detection performance, there was no difference between the preparation effect for threatening and neutral stimuli (Experiment 1) or disgusting and joyful stimuli (Experiment 3). The preparation effects were also unaffected by the participant's anxiety level. Experiment 2 confirmed that the threatening images affected performance when the dot probe appeared after the image. These results suggest that the visual system increases alertness in response to any upcoming stimulus and further imply that the effects of emotional stimuli largely occur after, but not before, the stimuli appear.

In pain thou shalt bring forth children: the peak-and-end rule in recall of labor pain.

Childbirth is usually the most painful event of a mother's life, and resonates in individual and collective memory for years. The current study examined the relationship between the experience of labor pain and its recollection 2 days and 2 months after delivery. We found that despite the exceptional physical and emotional experiences of childbirth, the memory of the pain involved in labor was biased toward the average of the peak pain and the end pain, whereas the duration of the delivery had a relatively negligible effect on the recollected intensity of pain. A comparison of mothers whose labor ended with or without epidural analgesia corroborated previous findings that the level of pain toward the end of an experience greatly influences the way the overall experience is remembered. Although both short- and long-term retention of memories of labor exhibited the peak-and-end effect, having given birth before weakened the effect 2 months after delivery.

How does a threatening stimulus affect the memory of the display?

Ample research has suggested that visual attention is biased towards threat and it was argued that this bias is an essential component of survival and implicated in anxiety. However, it is less clear how this bias is translated into memory, and specifically into the memory of items presented near a threatening stimulus. Here, we investigated this issue by testing how well people remember neutral and threatening images presented under various task demands. On each trial, observers saw two images before performing a dot-probe task (Experiment 1), a colour discrimination task (Experiment 2), a global or local attention task (Experiment 3), or no task at all (Experiment 4). A recognition memory test was performed at the end of each experiment to assess how the presence of a threatening image influences the memory of both images presented in the display. In all experiments, overall memory was enhanced as more threatening images were presented in the display. However, this enhancement did not occur at the expense of the processing of the surroundings. That is, with the exception of the dot-probe task, memory performance was not affected by an adjacent threatening image. Together, these findings challenge trade-off accounts, which predict that the processing of a threatening stimulus should take place at the expense of the processing of nearby items. Instead, these findings suggest that any effect of threat on the visual processing of the display is short-lived and more limited than previously thought.

Reclaiming the Stroop Effect Back From Control to Input-Driven Attention and Perception.

According to a growing consensus, the Stroop effect is understood as a phenomenon of conflict and cognitive control. A tidal wave of recent research alleges that incongruent Stroop stimuli generate conflict, which is then managed and resolved by top-down cognitive control. We argue otherwise: control studies fail to account for major Stroop results obtained over a century-long history of research. We list some of the most compelling developments and show that no control account can serve as a viable explanation for major Stroop phenomena and that there exist more parsimonious explanations for other Stroop related phenomena. Against a wealth of studies and emerging consensus, we posit that data-driven selective attention best accounts for the gamut of existing Stroop results. The case for data-driven attention is not new: a mere twenty-five years ago, the Stroop effect was considered "the gold standard" of attention (MacLeod, 1992). We identify four pitfalls plaguing conflict monitoring and control studies of the Stroop effect and show that the notion of top-down control is gratuitous. Looking at the Stroop effect from a historical perspective, we argue that the recent paradigm change from stimulus-driven selective attention to control is unwarranted. Applying Occam's razor, the effects marshaled in support of the control view are better explained by a selectivity of attention account. Moreover, many Stroop results, ignored in the control literature, are inconsistent with any control account of the effect.

Speeded naming or naming speed? The automatic effect of object speed on performance.

We test the hypothesis that naming an object depicted in a picture and reading aloud an object's name are affected by the object's speed. We contend that the mental representations of everyday objects and situations include their speed, and that the latter influences behavior in instantaneous and systematic ways. An important corollary is that high-speed objects are named faster than low-speed objects, although object speed is irrelevant to the naming task at hand. The results of a series of 7 studies with pictures and words support these predictions.

A rational look at the emotional stroop phenomenon: a generic slowdown, not a stroop effect.

The role of Stroop processes in the emotional Stroop effect was subjected to a conceptual scrutiny augmented by a series of experiments entailing reading or lexical decision as well as color naming. The analysis showed that the Stroop effect is not defined in the emotional Stroop task. The experiments showed that reading, lexical decision, and color naming all are slower with emotional words and that this delay is immune to task-irrelevant variation and to changes in the relative salience of the words and the colors. The delay was absent when emotional and neutral words appeared in a single block. A threat-driven generic slowdown is implicated, not a selective attention mechanism associated with the classic Stroop effect.

Selective attention improves under stress: implications for theories of social cognition.

Three influential perspectives of social cognition entail conflicting predictions regarding the selectivity of performance under stress. According to the attention view, selectivity to the task-relevant attribute improves under stress because of reduced utilization of task-irrelevant attributes. According to the capacity-resource approach, stress depletes attentional resources wherefore selectivity fails for all but chronically accessible information. A third perspective, ironic process theory, similarly holds that selective attention fails under stress but adds that task-irrelevant information is rendered hyperaccessible. The theoretical derivations were tested in a series of experiments using 2 classes of selectivity measures, with special care taken to control for hitherto neglected factors of context The results showed that the selectivity of attention improved under stress, consistent with the prediction of the attention view.

Pitch memory and exposure effects.

Recent studies indicate that the ability to represent absolute pitch values in long-term memory, long believed to be the possession of a small minority of trained musicians endowed with "absolute pitch," is in fact shared to some extent by a considerable proportion of the population. The current study examined whether this newly discovered ability affects aspects of music and auditory cognition, particularly pitch learning and evaluation. Our starting points are two well-established premises: (1) frequency of occurrence has an influence on the way we process stimuli; (2) in Western music, some pitches and musical keys are much more frequent than others. Based on these premises, we hypothesize that if absolute pitch values are indeed represented in long-term memory, pitch frequency of occurrence in music would significantly affect cognitive processes, in particular pitch learning and evaluation. Two experiments were designed to test this hypothesis in participants with no absolute pitch, most with little or no musical training. Experiment 1 demonstrated a faster response and a learning advantage for frequent pitches over infrequent pitches in an identification task. In Experiment 2, participants evaluated infrequent pitches as more pleasing than frequent pitches when presented in isolation. These results suggest that absolute pitch representation in memory may play a substantial, hitherto unacknowledged role in auditory (and specifically musical) cognition.

Segregation of study items in memory determines the magnitude and direction of directed forgetting.

When words at study are divided into to-be-remembered and to-be-forgotten ones, people recall more of the former than of the latter in a surprise memory test for all words. In this study, we also tapped memory for word identity at study (forget or remember) by asking participants to reproduce in memory selected portions of the original words. We found word identity to be parasitic on word reproduction. As a result, there is a noted tendency to recall forget-words from study as remember-words in the memory test more than vice versa.

Accurate visuomotor control below the perceptual threshold of size discrimination.

BACKGROUND: Human resolution for object size is typically determined by psychophysical methods that are based on conscious perception. In contrast, grasping of the same objects might be less conscious. It is suggested that grasping is mediated by mechanisms other than those mediating conscious perception. In this study, we compared the visual resolution for object size of the visuomotor and the perceptual system. METHODOLOGY/PRINCIPAL FINDINGS: In Experiment 1, participants discriminated the size of pairs of objects once through perceptual judgments and once by grasping movements toward the objects. Notably, the actual size differences were set below the Just Noticeable Difference (JND). We found that grasping trajectories reflected the actual size differences between the objects regardless of the JND. This pattern was observed even in trials in which the perceptual judgments were erroneous. The results of an additional control experiment showed that these findings were not confounded by task demands. Participants were not aware, therefore, that their size discrimination via grasp was veridical. CONCLUSIONS/SIGNIFICANCE: We conclude that human resolution is not fully tapped by perceptually determined thresholds. Grasping likely exhibits greater resolving power than people usually realize.

Emotional dilution of the Stroop effect: a new tool for assessing attention under emotion.

In order to gauge in a precise fashion the capture of attention by emotional stimuli, we developed a new tool that imports the classic Stroop effect into the realm of emotion. Strooping the typical emotion tasks enabled the derivation of a pure intraitem measure of attention under emotion. The results of two experiments showed that the classic Stroop effects were smaller with emotion than with neutral words, demonstrating the power of emotion to bias attention. This emotional dilution of the Stroop effect can serve as a general-purpose tool for assessing attention under emotion.

Avoiding the approach trap: a response bias theory of the emotional Stroop effect.

In the laboratory, people classify the color of emotion-laden words slower than they do that of neutral words, the emotional Stroop effect. Outside the laboratory, people react to features of emotion-laden stimuli or threatening stimuli faster than they do to those of neutral stimuli. A possible resolution to the conundrum implicates the counternatural response demands imposed in the laboratory that do not, as a rule, provide for avoidance in the face of threat. In 2 experiments we show that when such an option is provided in the laboratory, the response latencies follow those observed in real life. These results challenge the dominant attention theory offered for the emotional Stroop effect because this theory is indifferent to the vital approach-avoidance distinction.

Changes over time in digital literacy.

The current study is a follow-up on the 2002 empirical study by Eshet-Alkalai and Amichai-Hamburger, which investigated digital literacy skills among different age groups. This study explores changes through time in digital literacy among the same participants 5 years later, and their performance is compared to new matched control groups. Results indicate an improvement over time among all age groups, but especially for the adults, in the tasks that require proficiency and technical control in using technology (e.g., photovisual and branching literacy skills). On the other hand, results indicate a drop in the skills that require creative and critical thinking (e.g., information and reproduction literacy skills), especially for the younger participants. Results show two major patterns of change over time: (a) closing the gap between younger and older participants in the tasks that emphasize proficiency and technical control and (b) widening the gap between younger and older participants in tasks that emphasize creativity and critical thinking. Based on the comparison with the matched control groups, we suggest that experience with technology, and not age, accounts for the observed lifelong changes in digital literacy skills.

Are spatial and dimensional attention separate? evidence from Posner, Stroop, and Eriksen tasks.

Do various operational definitions of visual attention tap the same underlying process? To address this question, we probed visual selective attention using orientation of attention, flanker, and Stroop tasks. These were embedded in combined designs that enabled assessment of each effect, as well as their interaction. For the orientation task, performance was poorer at unexpected than at expected locations. The flanker effects also differed across the two locations. In contrast, the Stroop effects were comparable at expected and unexpected locations. We conclude that spatial attention (tapped by the orientation and the flanker tasks) and dimensional attention (tapped by the Stroop task) engage separate processes of visual selection, both of which are needed in normal attention processing.

Interactive perceptual and attentional limits in visual extinction.

We report a case-study of YE, a 54-year-old person who suffered multiple shell injuries that caused a right-parietal lesion and left hemianopia, almost 30 years ago. We conducted 4 experiments using a basic extinction paradigm in which YE had to report single stimuli presented on the left or right or two stimuli presented simultaneously in both visual fields. We show that extinction was selectively affected both by increasing the relative perceptual salience of the contralesional stimulus and by cueing attention to the contralesional side. The effects of perceptual salience and attentional cueing interacted, with cueing being more effective when the stimuli had relatively high perceptual salience. The data are consistent with attentional and perceptual factors interacting to determine the competition between left and right side stimuli that underlies extinction.