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.     

Performance of retarded and nonretarded adolescents when processing relevant and irrelevant information.

The information-processing performance of 12 retarded and 12 nonretarded adolescents was compared. Using reaction time keys each subject classified color words, secondary color words, non-color words, non-sense syllables, and stick figures according to the color of ink in which each stimulus was presented. Reaction time of the nonretarded subjects was significantly faster than that of retarded subjects; color words and secondary color words significantly interfered with processing performance as measured by correct reaction time. The results indicate that the Stroop task interferes with response initiation rather than memory retrieval and that the locus of interference for retarded and nonretarded subjects is equivalent.     

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.     

Absorbed in thought: the effect of mind wandering on the processing of relevant and irrelevant events

This study used event-related potentials to explore whether mind wandering (task-unrelated thought, or TUT) emerges through general problems in distraction, deficits of task-relevant processing (the executive-function view), or a general reduction in attention to external events regardless of their relevance (the decoupling hypothesis). Twenty-five participants performed a visual oddball task, in which they were required to differentiate between a rare target stimulus (to measure task-relevant processes), a rare novel stimulus (to measure distractor processing), and a frequent nontarget stimulus. TUT was measured immediately following task performance using a validated retrospective measure. High levels of TUT were associated with a reduction in cortical processing of task-relevant events and distractor stimuli. These data contradict the suggestion that mind wandering is associated with distraction problems or specific deficits in task-relevant processes. Instead, the data are consistent with the decoupling hypothesis: that TUT dampens the processing of sensory information irrespective of that information's task relevance.     

Visual working memory declines when more features must be remembered for each object

The article reports three experiments investigating the limits of visual working memory capacity with a single-item probe change detection paradigm. Contrary to previous reports (e.g., Vogel, Woodman, & Luck, Journal of Experimental Psychology. Human Perception and Performance, 27, 92–114, 2001), increasing the number of features to be remembered for each object impaired change detection. The degree of impairment was not modulated by encoding duration, size of change, or the number of different levels on each feature dimension. Therefore, a larger number of features does not merely impair memory precision. The effect is unlikely to be due to encoding limitations, to verbal encoding of features, or to chunk learning of multifeature objects. The robust effect of number of features contradicts the view that the capacity of visual working memory can be described in terms of number of objects regardless of their characteristics. Visual working memory capacity is limited on at least three dimensions: the number of objects, the number of features per object, and the precision of memory for each feature.     

Activation of response codes by relevant and irrelevant stimulus information

Single-route models attribute stimulus-response compatibility effects to the difficulty of translation from stimulus to response. Dual-route models propose that compatibility effects reflect in part an additional direct, or automatic, activation route. Selected findings from three lines of research are reported that converge to provide evidence consistent with the view that the automatic activation route plays a role in compatibility effects. The data suggest that the activation produced via this route by relevant stimulus attributes influences response selection only when all mappings of stimuli to responses are known to be compatible.     

Stress affects the selection of relevant from irrelevant stimuli

Two experiments were used to examine the effects of stress on latent inhibition (LI; poorer learning with a previously exposed irrelevant stimulus rather than a novel stimulus). In Experiment 1, stress was induced in college students by threatening participants' self-esteem with a difficult number series completion test that was related to intelligence. In Experiment 2, the participants were job seekers who were either informed or not that the LI test was part of the selection process. In both experiments, LI was attenuated in high- as compared with low-stressed participants. The results suggest that stress and/or anxiety impairs the inhibition of irrelevant-preexposed stimuli. Implications for understanding the impaired selective attentional processes in schizophrenia and schizotypy are discussed.     

Representing tools: how two non-human primate species distinguish between the functionally relevant and irrelevant features of a tool

Few studies have examined whether non-human tool-users understand the properties that are relevant for a tool's function. We tested cotton-top tamarins (Saguinus oedipus) and rhesus macaques (Macaca mulatta) on an expectancy violation procedure designed to assess whether these species make distinctions between the functionally relevant and irrelevant features of a tool. Subjects watched an experimenter use a tool to push a grape down a ramp, and then were presented with different displays in which the features of the original tool (shape, color, orientation) were selectively varied. Results indicated that both species looked longer when a newly shaped stick acted on the grape than when a newly colored stick performed the same action, suggesting that both species perceive shape as a more salient transformation than color. In contrast, tamarins, but not rhesus, attended to changes in the tool's orientation. We propose that some non-human primates begin with a predisposition to attend to a tool's shape and, with sufficient experience, develop a more sophisticated understanding of the features that are functionally relevant to tools.     

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 importance of semantic similarity to the irrelevant speech effect

Irrelevant speech disrupts immediate recall of a short sequence of items. Salamé and Baddeley (1982) found a very small and nonsignificant increase in the irrelevant speech effect when the speech comprised items semantically identical to the to-be-remembered items, leading subsequent researchers to conclude that semantic similarity plays no role in the irrelevant speech effect. Experiment 1 showed that strong free associates of the to-be-remembered items disrupted serial recall to a greater extent than words that were dissimilar to the to-be-remembered items. Experiment 2 showed that this same pattern of disruption in a free recall task. Theoretical implications of these findings are discussed.     

Phonological similarity and the irrelevant speech effect: implications for models of short-term verbal memory

Three experiments studied the interaction between irrelevant speech and phonological similarity within both the remembered and the irrelevant auditory material. Phonological similarity within the remembered list impaired performance in both baseline and irrelevant speech conditions, whereas phonological similarity between the remembered and ignored irrelevant items did not influence performance. Although there was a tendency for similarity within the irrelevant items to reduce interference, this proved to be a less robust finding. Implications for the theoretical interpretation of the irrelevant speech effect are discussed.     

Phonological similarity and the irrelevant speech effect: Implications for models of short-term verbal memory

Three experiments studied the interaction between irrelevant speech and phonological similarity within both the remembered and the irrelevant auditory material. Phonological similarity within the remembered list impaired performance in both baseline and irrelevant speech conditions, whereas phonological similarity between the remembered and ignored irrelevant items did not influence performance. Although there was a tendency for similarity within the irrelevant items to reduce interference, this proved to be a less robust finding. Implications for the theoretical interpretation of the irrelevant speech effect are discussed.     

Changes in attention to relevant and irrelevant stimuli during spatial learning

Rats were trained in 2 experiments to find a submerged platform that was situated in 1 of 2 of the 4 corners of a rectangular pool with a curved long wall. Different landmarks occupied 2 of the corners on every trial, and the platform was always situated near a landmark. For the place group in each experiment, the location of the platform was indicated by the shape of the pool and stimuli outside the pool (place cues), but not the landmarks within the pool. For the landmark groups, the landmarks, not the place cues, indicated where the platform could be found. During Stage 2, 2 of the place cues were relevant, and 2 of the landmarks were irrelevant, for a new discrimination. The place cues better controlled searching for the platform in the place group than in the landmark group when the place cues had initially been relevant by signaling the presence (Experiment 1) or the absence (Experiment 2) of the platform. The results show that animals pay more attention to relevant than irrelevant cues.     

Visual similarity in short-term recall for where and when

Two experiments examined the effects of visual similarity on short-term recall for where and when in the visual spatial domain. A series of squares of similar or dissimilar colours were serially presented at various locations on the screen. At recall, all coloured squares were simultaneously presented in a random order at the bottom of the screen, and the locations used for presentation were indicated by white squares. Participants were asked to place the colours at their appropriate location in their presentation order. Performance for location (where) and order (when) was assessed separately. Results revealed that similarity severely hinders both memory for what was where and memory for what was when, under quiet and articulatory suppression conditions. These results provide further evidence that similarity has a major impact on processing relational information in memory.     

Visual similarity in short-term recall for where and when

Two experiments examined the effects of visual similarity on short-term recall for where and when in the visual spatial domain. A series of squares of similar or dissimilar colours were serially presented at various locations on the screen. At recall, all coloured squares were simultaneously presented in a random order at the bottom of the screen, and the locations used for presentation were indicated by white squares. Participants were asked to place the colours at their appropriate location in their presentation order. Performance for location (where) and order (when) was assessed separately. Results revealed that similarity severely hinders both memory for what was where and memory for what was when, under quiet and articulatory suppression conditions. These results provide further evidence that similarity has a major impact on processing relational information in memory.