A sequential analysis of relevant and irrelevant information in the Stroop task

The effect of repeating relevant (colour) and irrelevant (word) stimulus information is investigated in two Stroop tasks. Thomas (1977) observed that the Stroop effect is reduced when the irrelevant word is repeated from trial n -1 to trial n. A similar effect was observed in the Simon task (Notebaert, Soetens, & Melis, 2001; Notebaert & Soetens, 2003a). MacLeod (1991) interprets this effect as sustained suppression and relates it to negative priming. In this paper we investigate whether the reduced Stroop effect for word repetitions is indeed related to the negative priming effect. In Experiment 1 with a response-stimulus interval (RSI) of 50 ms, the Stroop effect is not influenced by the sequence of the word and there is no negative priming effect. In Experiment 2 with an RSI of 200 ms, the Stroop effect is reduced for word repetitions but there is still no negative priming effect. This does not support the sustained-suppression hypothesis. The reduced Stroop effect for word repetitions is explained in terms of response priming.     

The effects of irrelevant relations on the processing of sequential patterns

Letter series completion problems varying along location of irrelevant relations (beginning, end, none) were presented to 24 Ss. A repeated-measures analysis of solution times and errors revealed that irrelevant relations at the beginning of series produced the longest latencies and the most errors. Using a pattern induction/sequence production model of serial processing, an error analysis showed production error rate remained constant across treatments, while pattern induction errors varied with confusion location. The results indicate that the difficulty of sequential processing varies with irrelevant relations only during the pattern induction phase. The findings also support a left-right generate-and-test model of pattern induction for the task.     

The effect of a prior presentation on temporal judgments in a perceptual identification task

Subjects read aloud words presented once at the rate of one per second. A perceptual identification task, involving 30- or 50-msec presentations, followed. Some of the words presented for identification had been read previously; others were new. After each presentation, in addition to identifying the word, the subjects judged its duration. The data indicate that a single presentation of a word affects its later perception, as revealed by enhanced perceptual identification, longer duration judgments, and better temporal discrimination. A second experiment showed that a single presentation influenced duration judgments even when identification was not required. The final experiment addressed the issue of what is preserved in memory from a prior presentation. The results from the three experiments indicate that duration judgments provide a valuable dependent measure of memory in the perceptual identification task and support the misattribution hypothesis: A prior presentation enhances perceptual identification, and this increase in relative perceptual fluency is incorrectly attributed to a longer presentation duration.     

The influence of similarity between relevant and irrelevant information upon a complex identification task

This experiment sought answers to two questions: (1) Do increases in the similarity between relevant and irrelevant information present in visual stimulus patterns detrimentally influence the performance of a complex identification task, and (2) does the effect of such similarity interact with increasing amounts of irrelevant information? An analysis of the response latencies and errors indicated that identification of the relevant information in the stimulus patterns becomes significantly poorer with increasing similarity between relevant and irrelevant information and with increasing amounts of irrelevancy. The results also showed that the joint effect of similarity and irrelevancy produces a greater performance decrement than that associated with either variable alone. Practice on the task reduced the detrimental effects.     

Mixing costs in task shifting reflect sequential processing stages in a multicomponent task

We investigated the hypothesis that mixing costs intask shifting reflect th e sequential selection of task components (e.g., stimulus categories) during task execution. This proposition was supported by Hübner, Futterer, and Steinhauser (2001), who showed that the amount of mixing costsdepends on the number of mixed task components (e.g., stimulus level and judgment). However, their results could also be explained by a task set selection account, because task components and task sets were confounded. In Experiments 1 and 2, we compared conditions in which either the number of task sets varied and the number of mixed task components was constant or vice versa. Only the number of mixed task components was predictive for the mixing costs. In Experiment 3, we replicated the additivity of mixing costs from level a ndjudgment mixing. Our results suggest thatthe mixingcosts reflect a selection strategy in which interference is reduced in a stepwise manner.     

Competing responses and the processing of irrelevant information

A number of studies have shown that performance of identification and discrimination tasks is detrimentally affected by irrelevant information, yet other studies have failed to find such decrements. It is suggested that these contradictory findings depend on whether S must make difficult discriminations among the relevant stimuli, the irrelevant stimuli, or between the relevant and irrelevant stimuli. The role of irrelevant information in these tasks is to enhance or amplify the competihg responses engendered by the difficult discriminations. Irrelevant information enhances competing responses by increasing the information processing requirements of a task. The results of various studies of irrelevant information seem to be in good agreement with the assertions.     

The effect of language cues on infants' representational flexibility in a deferred imitation task

Twelve- and 15-month-old infants who received simple verbal cues at encoding and retrieval exhibited superior representational flexibility on an imitation task compared to infants who did not receive those cues. Verbal cues can help early-verbal infants overcome perceptual dissimilarity and express knowledge in novel situations.     

The effect of mental practice on performance in a sequential reaction time task

The effect of mental practice on performance in a dot-location RT task was investigated. Participants (N = 40) were required either to mentally practice, physically practice, or do no practice on an RT task in which the signals appeared in a repeating sequence. Correct mental practice, as opposed to incorrect mental practice and no practice, was predicted to have a positive (enhancing) effect on performance of the RT task. Despite previous evidence that mental rehearsal does enhance performance in many perceptual-motor tasks, neither correct nor incorrect mental rehearsal affected subsequent sequence learning; that is, no mental practice effect was observed. That surprising result is discussed in terms of motivational, psychoneuromuscular, separate memory systems, and transfer-appropriate processing explanations of mental practice.     

Evidence for graded central processing resources in a sequential movement task

In the present experiment, we examined slowing of the individual key presses of a familiar keying sequence by four different versions of a concurrent tone counting task. This was done to determine whether the same cognitive processor that has previously been assumed by the dual processor model (DPM) to initiate familiar keying sequences and assist in their execution, is involved also in the central processes of a very different task (viz. identifying tones and counting target tones). The present results confirm this hypothesis. They also suggest that in this particular situation the central processing resources underlying the cognitive processor can be distributed across the central processes of different tasks in a graded manner, rather than that they continue to behave like a single, central processor that serially switches between the central processes of the concurrently performed tasks. We argue that the production of highly practiced movement sequences can be considered automatic in the sense that execution of familiar movement sequences can continue without cognitive control once they have been initiated.     

Some stages of information processing in a choice reaction-time task

Eight pigeons were tested for head nystagmus in a rotating drum with vertical black and white bars on the reside. When the birds viewed monocularly, they gave about four times as many responses to nasalward as to temporalward movement. However, no such asymmetry was observed in a discrimination paradigm. Six pigeons were taught binocularly to discriminate moving lines, which moved equally often to left and fight, from stationary fines. They were then tested monoculaxly, and the discrimination was controlled about equally by nasalward and temporalward movement.     

Infant temperament and information processing in a visual categorization task

This study investigates the relation between temperament and information processing in 7-month-old infants. Infant temperament was assessed on multiple dimensions, using mothers' ratings on the Infant Behavior Questionnaire (IBQ). Information processing was measured during a paired-comparison visual categorization task. Infants (N=50) were familiarized with five different pairs of visual stimuli from one category, followed by two test trials, each contrasting a novel familiar-category item with a novel out-of-category item (animals vs. vehicles). Drop-out rate in this task was within a normal range (21%). No differences in temperament were found between completers and non-completers, but high reactivity to novelty and low motor activity were positively correlated with the strength of infants' familiarization response. Group comparisons between infants scoring high and low on these two dimensions of temperament confirmed this general finding: infants high on distress to novelty and low on motor activity showed stronger familiarization responses. Furthermore, infants scoring low on motor activity showed a stronger categorization response than highly active infants. This study provides evidence that performance in a cognitive categorization task and dimensions of infant temperament are systematically related during the second half of the first year of life. Implications for cognitive research with infants of this age-range will be discussed.     

Anchoring in sequential judgments

Building on the scale distortion theory (Frederick & Mochon, 2012), we explore the boundary conditions of anchoring outside of the standard paradigm. We argue that the conditions needed for anchoring effects are much more restrictive than those suggested by some theories, but much less restrictive than those suggested by others. Our findings illuminate both the scope and limits of this well-known effect and provide a framework for predicting its occurrence in novel settings.     

Stress reduces attention to irrelevant information: Evidence from the Stroop task

Stroop interference can be reduced by stress, and this has been taken as evidence that stress decreases the attention paid to irrelevant information, a theory known as ‘Easterbrook’s hypothesis’. This contradicts more recent theories, which state that attentional control deteriorates in stress. Fifty-five participants undertook a Stroop task under high stress (loud white noise) and low stress conditions. Attention to the irrelevant word information was assessed by manipulating the proportion of congruent trials (e.g. the word RED in the colour red); it is known that Stroop interference increases when many such trials are presented. This effect was reduced when participants were stressed, which is evidence that stress does indeed reduce attention to irrelevant information. This pattern of results was not present in participants with low working memory spans, presumably because these participants had less attentional control. These findings highlight an important weakness in contemporary theories of cognition in stress.     

Influence of similarity between target and irrelevant items on visual information processing.

6 undergraduate subjects searched circular stimulus displays of upper case letters of the alphabet for a pre-specified single target letter. The displays were given a masked exposure of 100 msec, and contained 1, 5, 11, or 17 irrelevant items which were either similar or dissimilar in shape to the target. It was anticipated that these conditions would provide a test of Neisser's (1967) notion of attention. The results, which showed that similarity, numbers and their interaction were significant, could not be explained by wholly serial or parallel models of information processing as they failed to account for the interaction. To explain the interaction it was necessary to consider processing by preattention and focal attention.     

The influence of relevant and irrelevant stereoscopic depth cues: Depth information does not always capture attention

Previous research reported ambiguous findings regarding the relationship of visuospatial attention and (stereoscopic) depth information. Some studies indicate that attention can be focused on a distinct depth plane, while other investigations revealed attentional capture from irrelevant items located in other, unattended depth planes. To evaluate whether task relevance of depth information modulates the deployment of attentional resources across depth planes, the additional singleton paradigm was adapted: Singletons defined by depth (i.e., displayed behind or in front of a central depth plane) or color (green against gray) were presented among neutral items and served as targets or (irrelevant) distractors. When participants were instructed to search for a color target, no attentional capture from irrelevant depth distractors was observed. In contrast, it took substantially longer to search for depth targets when an irrelevant distractor was presented simultaneously. Color distractors as well as depth distractors caused attentional capture, independent of the distractors’ relative depth position (i.e., in front of or behind the target). However, slight differences in task performance were obtained depending on whether or not participants fixated within the target depth plane. Thus, the current findings indicate that attentional resources in general are uniformly distributed across different depth planes. Although task relevant depth singletons clearly affect the attentional system, this information might be processed subsequent to other stimulus features.