On the locus of redundancy effects in a letter-detection task

It takes longer to detect a target if it is the initial letter of a nonredundant letter string such as BNHTW than if it is the initial letter of a redundant letter string such as BBBBB (Johnson, 1986b; Johnson & Blum, 1988). The results of the present study reveal that the redundancy effect also occurs for mixed-case letters strings (e.g., BbbBb) and digit strings (e.g., 22222). In addition, these results suggest that the cause of the redundancy effect is not related to the visual properties of the noninitial letters per se but is instead related to the presence of the target in noninitial positions. Together, these results rule out a number of hypotheses about the cause of the redundancy effect and suggest that the locus of this effect is in processes involved in response selection and/or the read-out of information from the perceptual system.     

The distractor frequency effect in a delayed picture-word interference task: further evidence for a late locus of distractor exclusion

A picture-word interference experiment examined the origin of the distractor frequency effect, the effect that pictures are named slower in the context of low-frequency than high-frequency words (Miozzo &; Caramazza, Journal of Experimental Psychology, 132, 228–252, 2003). We compared two accounts of the effect: an early, input-related account and a late, response-related account. Participants named high and low-frequency pictures with low and high-frequency distractors in two conditions. In the immediate naming condition, picture and distractor were presented simultaneously. In the delayed naming condition, the distractor was presented 1,000 ms after the picture; pictures had to be named upon distractor presentation. There was a distractor frequency effect in both conditions, but an effect of picture frequency only in the immediate naming condition (showing that in the delayed naming condition, lexical selection had been completed). These results support a late origin of the distractor frequency effect.     

The picture superiority effect in a cross-modality recognition task

Words and pictures were studied, and recognition tests were given in which each studied object was to be recognized in both word and picture format. The main dependent variable was the latency of the recognition decision. The purpose was to investigate the effects of study modality (word or picture), of congruence between study and test modalities, and of priming resulting from repeated testing. Experiments 1 and 2 used the same basic design, but the latter also varied retention interval. Experiment 3 added a manipulation of instructions to name studied objects, and Experiment 4 deviated from the others by presenting both picture and word referring to the same object together for study. The results showed that congruence between study and test modalities consistently facilitated recognition. Furthermore, items studied as pictures were more rapidly recognized than were items studied as words. With repeated testing, the second instance was affected by its predecessor, but the facilitating effect of picture-to-word priming exceeded that of word-to-picture priming. The findings suggest a two-stage recognition process, in which the first is based on perceptual familiarity and the second uses semantic links for a retrieval search. Common-code theories that grant privileged access to the semantic code for pictures or, alternatively, dual-code theories that assume mnemonic superiority for the image code are supported by the findings. Explanations of the picture superiority effect as resulting from dual encoding of pictures are not supported by the data.     

Differential payoff and locus of selectivity in a visual memory task

Two experiments were run to investigate the locus of selectivity in a visual memory task involving differential payoff for letters correctly recalled: Major variables consisted of value instructions given before or after the exposure of a display, the ratio of high to low value, and exposure duration. The results showed that Ss make more correct reports of higher value than of lesser value, whether value instructions are given before or after the display. Furthermore, overall performance and extent of selectivity increase with increasing exposure time, but more for the before than the after conditions of instruction. These results suggest that selectivity occurs both during perception and retention and during recall.     

The effect of cueing in a visual signal detection task

In a signal detection task four subjects were presented with stimulus cards, 50% of which contained a capital O in one of the four quadrants. Fifty per cent of these Os were surrounded by a small rectangle. This small rectangle served as a simultaneous cue, indicating the region where the O could appear. The other 50% were surrounded by a big rectangle encompassing the whole field. Fifty per cent of the blank cards contained a small rectangle, the other 50% a big one. Exposure duration was set at 15 and 20 ms. The results indicated that subjects, for whom these exposure durations led to performance exceeding chance level, used the simultaneous cue for reducing the field to be searched, resulting in higher sensitivity (d') in the small rectangle condition. Results were interpreted in terms of increasing efficiency of search as a result of which a higher quality of the icon was available for making decisions about the presence of the O.     

The cognitive locus of distraction by acoustic novelty in the cross-modal oddball task

Unexpected stimuli are often able to distract us away from a task at hand. The present study seeks to explore some of the mechanisms underpinning this phenomenon. Studies of involuntary attention capture using the oddball task have repeatedly shown that infrequent auditory changes in a series of otherwise repeating sounds trigger an automatic response to the novel or deviant stimulus. This attention capture has been shown to disrupt participants' behavioral performance in a primary task, even when distractors and targets are asynchronous and presented in distinct sensory modalities. This distraction effect is generally considered as a by-product of the capture of attention by the novel or deviant stimulus, but the exact cognitive locus of this effect and the interplay between attention capture and target processing has remained relatively ignored. The present study reports three behavioral experiments using a cross-modal oddball task to examine whether the distraction triggered by auditory novelty affects the processing of the target stimuli. Our results showed that variations in the demands placed on the visual analysis (Experiment 1) or categorical processing of the target (Experiment 2) did not impact on distraction. Instead, the cancellation of distraction by the presentation of an irrelevant visual stimulus presented immediately before the visual target (Experiment 3) suggested that distraction originated in the shifts of attention occurring between attention capture and the onset of the target processing. Possible accounts of these shifts are discussed.     

The effect of a subsidiary task on iconic memory

Memory & Cognition - Using a subsidiary task technique, Doest and Turvey (1971) concluded that iconic memory was independent of the central processing system. However, they did not control the...     

The effect of a non-informative cueing signal in a three-choice reaction-time task

Summary Many studies have shown that in a simple reaction-time (RT) task a non-informative leading cue decreases RT to a subsequent target presented in the same region as the cue. This facilitation lasts about 150 ms; it is then replaced by a sustained inhibition. Experiment 1 tests the hypothesis that the initial facilitation is due to motor, rather than perceptual, processes by using choice RT. Facilitation is greater and lasts longer in choice than in simple tasks, thus supporting the hypothesis. Experiment 2 shows that facilitation occurs even when the subject actively orients his or her attention away from the cue.     

The effect of combinations of image degradations in a discrimination task

This paper explores the ways in which combinations of image degradations affect discrimination. Nine experiments are described that examine the discriminability of visual images that are degraded with three types of information reducing transformations: random punctate visual interference, lowpass spatial frequency filtering, and local area (i.e., block) averaging. The results of these experiments characterize a powerful visual ability to discriminate highly degraded stimuli unless that ability is severely challenged by relatively high levels of random visual interference. Discriminative commutativity of the orders in which the other two degradations are imposed is demonstrated. That is, the order in which the degradations are applied does not affect the final discriminative outcome. This result is in contrast to predictions from relevant mathematics and direct examination of the images produced by both orders of degradation. The commutativity is attributed to the particularly strong effect of the low-pass spatial frequency filtering degradation on the discrimination process. This study also demonstrates that combinations of degradations in a discrimination task always result in a reduction in performance, and never in the improvement that has been reported for recognition. This difference is attributed to the fact that form discrimination is mediated mainly by local features and high-frequency spatial components, whereas recognition is mediated mainly by global features and low-frequency spatial components.     

The effect of rotation on configural encoding in a face-matching task

Inversion disrupts encoding of faces because of the disruption of configural encoding as evident in the Thatcher illusion (Thompson 1980, Perception 9 483-484). Here we consider the effect of rotation on the loss of configural encoding in a same/different matching paradigm. Participants decided whether two faces were of the same type (both normal or both Thatcherised) or not, at five angles of rotation (0 degrees, 45 degrees , 90 degrees, 135 degrees, 180 degrees). When the faces were both of the same person, the disruption due to rotation for 'same-type' judgments was linear and approximately equal for normal and Thatcherised face pairs. In experiment 2, with different-person face pairs, the effect of rotation was much greater for Thatcherised face pairs than for normal face pairs. These findings are in contrast to those reported by Boutsen and Humphreys (2003, Quarterly Journal of Experimental Psychology A 56 955-975), and reasons for these differences, along with implications, are discussed.     

The effect of visual orientation uncertainty in a simultaneous detection-recognition task

This study concerned the processing of the outputs of visual orientation-sensitive mechanisms by higher order mechanisms. Ss performed a simultaneous detection-recognition task. Variation in the number of possible orientations of a single straight line produced only slight, if any, changes in detection or recognition performance as compared with findings from similar auditory frequency experiments. It was concluded that the outputs of all orientation-sensitive mechanisms are examined by higher order mechanisms. As the angular separation of two possible orientations increased, the data showed that recognition improved in keeping with other reported findings. Comparison of detection with recognition indicated that the latter, under certain conditions, was superior to the former.     

The effect of stimulus availability on task choice in voluntary task switching

The voluntary task switching paradigm allows subjects to choose which task to perform on each trial in a stimulus environment affording multiple tasks. The present study examined the effect of stimulus availability on task choice. Subjects viewed displays containing a digit and a letter and performed either an even/odd or a consonant/vowel judgment on each trial. The target stimuli appeared with a stimulus onset asynchrony (SOA) of 0, 50, 100, or 150 msec. The probability of performing the task associated with Stimulus 1 increased as SOA increased, indicating an effect of external or stimulus-driven factors on task choice. This effect of stimulus availability on task choice was greater when the response-stimulus interval was 400 msec than when it was 2,000 msec. This interaction of preparation interval and stimulus availability is explained within a model of task choice that includes both internal processes and external influences.     

The effect on a difficult co-ordination task of the frequency of signals

Subjects were required to direct, by moving hand and foot controls, a fugitive spot of light into one of four positions in accordance with changes in the source of signals, and simultaneously, to extinguish two lights using a left-hand response. Two groups of subjects have been tested on this complex co-ordination task. Increasing the frequency of the signals from four successively but irregularly functioning sources was found to increase significantly the “error” scores in controlling the fugitive spot. Variations in signal frequency did not affect the other part of the task requiring left hand responses to a different set of signals. The order of a sequence of 4-signal frequencies over four trials had no effect on the efficiency with which the task was performed.     

Internal-external locus of control and performance on a vigilance task.

Previous studies have demonstrated there are large individual differences in subjects' ability to perform on vigilance or watch-keeping tasks. This study used Rotter's Internal-External (I-E) Locus of Control Scale to resolve some of the variance attributed to individual differences and tested the hypothesis that the internally controlled person is a better monitor on a vigilance task than an externally controlled person. There were 64 subjects who performed a visual watch-keeping task for a 1-hr. period. The results indicated that the external subjects made significantly more incorrect responses and missed significantly more signals during the entire task. The internal-external dimension was effective in differentiating performance on a vigilance task.     

The effect of culture on a visual-spatial memory task.

The visual-spatial memory ability of 25 Zairian elementary school children was compared with that of 23 Scottish children, using a variation of Kearins's (1976) object placement task. The Scottish children demonstrated significantly better visual-spatial memory than the Zairian children when the easiest (small household objects) of three arrays was presented. The Scottish and Zairian children demonstrated a similar level of visual-spatial ability when the other two arrays (geometric shapes and a variety of natural pieces of wood) were presented, and there were no significant gender differences. Although the Australian Aboriginal children's performance on the visual-spatial task in Drinkwater's (1976) study was superior to the White children's performance (Kearins, 1976, 1981), the Zairian children's performance in this study was not. Perhaps the Aboriginal groups, over countless generations navigating the trackless desert of western Australia, were forced by their environment to develop an aptitude for direction finding that Zairians (whose ecological situation more closely resembles that of Europeans) have not.     

More than a surprise: The bivalency effect in task switching

When switching tasks, if stimuli are presented that contain features that cue two of the tasks in the set (i.e., bivalent stimuli), performance slowing is observed on all tasks. This generalized slowing extends to tasks in the set which have no features in common with the bivalent stimulus and is referred to as the bivalency effect. In previous work, the bivalency effect was invoked by presenting occasionally occurring bivalent stimuli; therefore, the possibility that the generalized slowing is simply due to surprise (as opposed to bivalency) has not yet been discounted. This question was addressed in two task switching experiments where the occasionally occurring stimuli were either bivalent (bivalent version) or merely surprising (surprising version). The results confirmed that the generalized slowing was much greater in the bivalent version of both experiments, demonstrating that the magnitude of this effect is greater than can be accounted for by simple surprise. This set of results confirms that slowing task execution when encountering bivalent stimuli may be fundamental for efficient task switching, as adaptive tuning of response style may serve to prepare the cognitive system for possible future high conflict trials.     

The effect of orthographic and emotional neighbourhood in a colour categorization task

This study investigated whether and how the strength of reading interference in a colour categorization task can be influenced by lexical competition and the emotional characteristics of words not directly presented. Previous findings showed inhibitory effects of high-frequency orthographic and emotional neighbourhood in the lexical decision task. Here, we examined the effect of orthographic neighbour frequency according to the emotional valence of the higher-frequency neighbour in an emotional orthographic Stroop paradigm. Stimuli were coloured neutral words that had either (1) no orthographic neighbour (e.g. PISTIL [pistil]), (2) one neutral higher-frequency neighbour (e.g. tirade [tirade]/TIRAGE [draw]) or (3) one negative higher-frequency neighbour (e.g. idiome [idiom]/IDIOTE [idiotic]). The results showed that colour categorization times were longer for words with no orthographic neighbour than for words with one neutral neighbour of higher frequency and even longer when the higher-frequency neighbour was neutral rather than negative. Thus, it appears not only that the orthographic neighbourhood of the coloured stimulus words intervenes in a colour categorization task, but also that the emotional content of the neighbour contributes to response times. These findings are discussed in terms of lexical competition between the stimulus word and non-presented orthographic neighbours, which in turn would modify the strength of reading interference on colour categorization times.     

The task rule congruency effect in task switching reflects activated long-term memory

Reaction time task rule congruency effects (RT-TRCEs) reflect faster responses to stimuli for which the competing task rules indicate the same correct response than to stimuli indicating conflicting responses. The authors tested the hypothesis that RT-TRCE reflects activated overlearned response category codes in long-term memory (such as up or left). The results support the hypothesis by showing that (a) RT-TRCE was absent for tasks for which there were no response codes ready beforehand, (b) RT-TRCE was present after these tasks were practiced, and (c) these practice effects were found only if the tasks permitted forming abstract response category codes. The increase in the RT-TRCE with response slowness, found only for familiar tasks, suggests that the abstract response category codes may be verbal or linguistic in these cases. The results are discussed in relation to task-switching theories and prefrontal functions.     

The locus of the experimental effects in the rapid serial visual presentation (RSVP) task

A central assumption of studies using the rapid serial visual presentation (RSVP) technique is that it taps purely perceptual processes. In an experiment testing this assumption, subjects were presented with seven-word sentences that were either completely intact or had their final three words replaced by three extraneous words. The subjects were significantly less accurate in reporting the first four unchanged words of the sentences in the latter condition. Contrary to assumption, this result indicates that postperceptual factors are critical in the task. It is therefore argued that theoretical conclusions based on the technique should be treated cautiously until the locus of each effect has been established.