Global and local processing in nonattended objects: a failure to induce local processing dominance.

Paquet and Merikle (1988) found that subjects can ignore the category of unattended local forms but not that of global forms. Does this finding reflect a priority for global information during perception? In 5 studies, 2 compound stimuli, each surrounded by a frame, were presented side by side, and attention was directed to 1 of the stimuli. The first 2 studies examined whether local dominance would emerge if a small gap (Experiment 1) or the presence of small white lines (Experiment 2) on the surrounding frame specified the target object. No evidence for local dominance was found. Three additional studies examined whether local dominance would be obtained if subjects had extensive practice identifying the local aspect of stimulus displays. Although local practice led to automatic detection of unattended local targets, it did not affect the processing of the global aspect. These results are proposed to exemplify the priority of global information during perception.     

The repressor personality and avoidant information processing: A dichotic listening study

The present research was designed to investigate the proposition that repressors, operationally defined by the conjunction of low anxiety and high defensiveness, are particularly adept at avoiding the processing of information when motivated to do so. Four groups of participants (nondefensive-low anxious, high anxious, repressors, and defensive-high anxious) were administered a dichotic listening task involving neutral or negative affective words presented in the unattended ear. Participants shadowed the material presented to the attended ear and simultaneously responded to a probe task presented on a video monitor. Results revealed that repressors made significantly fewer shadowing errors than high anxious and defensive-high anxious participants and marginally significantly fewer shadowing errors than low anxious participants for both neutral and negative words. High anxious participants, however, were later able to recognize the negative words that had been presented to the unattended ear at well above chance levels, whereas the recognition memory of repressors for such negative unattended words was at chance levels. In addition, repressors' responses to a postexperiment questionnaire indicated a significantly greater number of distracting thoughts during the experiment relative to other participants. Repressors, it seems, are indeed skillful at avoidant information processing and this capacity may well be related to the emotional memory deficits they have displayed in previous research.     

Representation of unattended material in memory

The current study addresses how information whose processing was not part of task requirement (unattended) is represented in memory. Using a novel measure, recognition memory for unattended material was assessed twice, once when it appeared with the same (old) attended study target and once with a new target. The data reveal memory for unattended study information only in the old target condition. Results suggest that the entire study event is encoded and represented in a memory trace, which contains both attended target information along with unattended context information. In conclusion, manifestation of unattended memory may be dependent on the presence of old target information at test.     

Overlapping mechanisms of attention and spatial working memory

Spatial selective attention and spatial working memory have largely been studied in isolation. Studies of spatial attention have provided clear evidence that observers can bias visual processing towards specific locations, enabling faster and better processing of information at those locations than at unattended locations. We present evidence supporting the view that this process of visual selection is a key component of rehearsal in spatial working memory. Thus, although working memory has sometimes been depicted as a storage system that emerges 'downstream' of early sensory processing, current evidence suggests that spatial rehearsal recruits top-down processes that modulate the earliest stages of visual analysis.     

“Sensory gating” as a mechanism for visuospatial orienting: Electrophysiological evidence from trial-by-trial cuing experiments

Stimuli at attended-to locations in visual space are usually detected with higher speed and accuracy than stimuli at unattended positions. It has been argued that this effect is due to “sensory gating” mechanisms that modulate the flow of perceptual information from attended and unattended positions. In the present experiments, event-related potentials (E32Ps) were recorded to stimuli that were preceded either by a valid or by an invalid positional cue (trial-by-trial cuing). When overt responses were required only to infrequent target stimuli in valid trials (Experiment 2) or to all validly cued stimuli (Experiment 2B), but not to invalid trials, systematic enhancements of early sensory-evoked potentials were found. These effects were smaller when both validly and invalidly cued stimuli required a response (Experiment 2A). These findings are interpreted as evidence that sensory gating processes are activated during the trial-by-trial suing of spatial attention. Furthermore, valid stimuli elicited a greater negativity than invalid stimuli at midline electrodes following the early enhancements of sensory-evoked potentials. This possibly reflects an additional enhanced processing of attended-to locations.     

The unattended speech effect: perception or memory?

Broadbent (1983) has suggested that the influence of unattended speech on immediate serial recall is a perceptual phenomenon rather than a memory phenomenon. In order to test this, subjects were required to classify visually presented pairs of consonants on the basis of either case or rhyme. They were tested both in silence and against a background of continuous spoken Arabic presented at 75 dB(A). No effect of unattended speech was observed on either the speed or accuracy of processing. A further study required subjects to decide whether visually presented nonwords were homophonous with real words. Again, performance was not impaired by unattended speech, although a clear effect was observed on an immediate serial memory task. Our results give no support to the perceptual interpretation of the unattended speech effect.     

Processing of form: further evidence for the necessity of attention

Using the materials and general procedure described by Rock and Gutman (1981), 160 subjects were required to attend selectively to a series of 10 red or green outlines of two overlapping contours. Immediately afterwards, six groups of 20 subjects were administered various kinds of recognition tests involving attended, unattended, or new figures, and two groups of 20 were asked to provide affect ratings of the test stimuli. Consistent with the findings of Rock and Gutman in 1981, attended outlines were selected as old more often than unattended or new ones. Although some data in a single-stimulus condition suggested that the unattended forms were "discriminated negatively," this effect was not replicated with forced-choice testing. Over-all, there was little evidence that, on unattended forms, subjects were significantly more accurate, differentially confident or displayed more liking than on new ones. These results are interpreted as supporting the view that attention is required for the cognitive representation of form.     

Spatial attention in early vision

The present study addressed whether the allocation of attention to a particular region in space can prevent processing of distractor information from non-attended regions. A cue indicated the area in visual space where the target singleton would be presented. Observers were required to detect this target singleton and ignore a distractor singleton presented within a non-attended region. The results indicate that the allocation of attention to a region in space cannot prevent the processing of unwanted information from elsewhere in the visual field. It is concluded that the function of the allocation of attention is not to enhance the processing capacity within the attended region but rather to attenuate interference from distractors in unattended regions.     

Processing of written and spoken words: Evidence for common coding

Common processing systems involved during reading and listening were investigated. Semantic, phonological, and physical systems were examined using an experimental procedure that involved simultaneous presentation of two words: one visual and one auditory. Subjects were instructed to attend to only one modality and to make responses on the basis of words presented in that modality. Influence of unattended words on semantic and phonological decisions indicated that these processing systems are common to the two modalities. Decisions in the physical task were based on modality-specific codes operating prior to the convergence of information from the two modalities.     

Selective looking: Attending to visually specified events

Subjects looked at two optically superimposed video sccreens, on which two different kinds of things were happening. In the principal condition, they were required to follow the action in one episode (by pressing keys when significant events occurred) and ignore the other. They could do this without difficulty, although both were present in the same fully overlapped visual field. Odd events in the unattended episode were rarely noticed. It was very difficult to monitor both episodes at once. Performance was no better when the two episodes were presented to different eyes (dichoptic condition) than when both were given binocularly. It is argued that selective attention does not involve special mechanisms to reject unwanted information, but is a direct consequence of skilled perceiving.     

Differences in the neural mechanisms of selective attention in children from different socioeconomic backgrounds: an event‐related brain potential study

Previous research indicates that children from lower socioeconomic backgrounds show deficits in aspects of attention, including a reduced ability to filter irrelevant information and to suppress prepotent responses. However, less is known about the neural mechanisms of group differences in attention, which could reveal the stages of processing at which attention deficits arise. The present study examined this question using an event‐related brain potential (ERP) measure of selective auditory attention. Thirty‐two children aged from 3 to 8 years participated in the study. Children were cued to attend selectively to one of two simultaneously presented narrative stories. The stories differed in location (left/right speaker), narration voice (male/female), and content. ERPs were recorded to linguistic and non‐linguistic probe stimuli embedded in the attended and unattended stories. Children whose mothers had lower levels of educational attainment (no college experience) showed reduced effects of selective attention on neural processing relative to children whose mothers had higher levels of educational attainment (at least some college). These differences occurred by 100 milliseconds after probe onset. Furthermore, the differences were related specifically to a reduced ability to filter irrelevant information (i.e. to suppress the response to sounds in the unattended channel) among children whose mothers had lower levels of education. These data provide direct evidence for differences in the earliest stages of processing within neural systems mediating selective attention in children from different socioeconomic backgrounds. Results are discussed in the context of intervention programs aimed at improving attention and self‐regulation abilities in children at‐risk for school failure.     

Processing Pitch and Temporal Structures in Music Reading: Independent or Interactive Processing Mechanisms?

Music provides a useful domain in which to study how the different attributes of complex multidimensional stimuli are processed both separately and in combination. Much research has been devoted to addressing how the dimension of pitch and time are co-processed in music listening tasks. Neuropsychological studies have provided evidence for a certain degree of independence between pitch and temporal processing, although there are also many experimental reports favouring interactive models of pitch and temporal processing. Here we extended these investigations by examining the processing of pitch and temporal structures when music is presented in the visual modality (i.e. in the form of music notation). In two experiments, musician subjects were presented with visual musical stimuli containing both pitch and temporal information for a brief amount of time, and they were subsequently required to recall both the pitch and temporal information. In Experiment 1, we documented that concurrent, unattended, pitch and rhythmic auditory interference stimuli disrupted the recall of pitch, but not time. In Experiment 2, we showed that manipulating the tonal structure of the visual presentation stimuli affected the recall of pitch, but not time. On the other hand, manipulating the metrical properties of the visual stimuli affected recall of time, and pitch to a certain extent. Taken together, these results suggest that the processing of pitch is constrained by the processing of time, but the processing of time is not affected by the processing of pitch. These results do not support either strong independence or interactive models of pitch and temporal processing, but they suggest that the processing of time can occur independently from the processing of pitch when performing a written recall task.     

Discrimination without awareness?

The fate of the unattended message in dichotic listening experiments is a much disputed issue. Moray (1969) proposes that there is no processing of the unattended message, whereas Norman (1969) has suggested that it is analyzed to the level of meaning. In order to test these alternative hypotheses an experiment was performed in which galvanic skin responses (GSR) were conditioned to a word (CS) by pairing it with shock. The word was then included in passages of prose presented to subjects as the attended and unattended messages in a dichotic listening task. GSR's were obtained to the occurrence of CS in the unattended message and also to words acoustically similar to CS and to synonyms of CS. The probability of obtaining a GSR to the occurrence of an accoustically similar word was increased by placing that word in a context appropriate to CS. These results suggest that the unattended message can be processed to a level at which semantic information is extracted without the subject's reported awareness.     

Negative priming of unattended part primes: Implications for models of holistic and analytic processing in object recognition

The “hybrid” model of object recognition (Hummel, 2001) proposes that unattended objects are processed holistically, while attended objects are processed both holistically and analytically. Supporting evidence for this claim was reported by Thoma, Hummel, and Davidoff (2004) who showed that, unlike whole object primes, unattended split object parts (presumed to require analytic processing) do not elicit repetition priming. Here we tested the generality of this finding by contrasting priming for whole and part prime stimuli as a function of prime informativeness and by modifying the design so that both unattended whole and part prime displays contained a single perceptual object. Unlike Thoma et al. (2004) the results showed negative (rather than an absence of) priming for unattended half object primes. These findings place new constraints on theoretical models of the role of attention in object recognition.     

Facilitation and disruption of lateralized syllable processing by unattended stimuli in the opposite visual field

The influence of lateralized unattended stimuli on the processing of attended stimuli in the opposite visual field can shed light on the nature of information that is transferred between hemispheres. On a cued bilateral task, participants tried to identify a syllable in the attended visual field, which elicits a left hemisphere (LH) advantage and different processing strategies by the two hemispheres. The same or a different syllable or a neutral stimulus appeared in the unattended field. Transmission of unattended syllable codes between hemispheres is symmetric, as revealed by equal interference for the two visual fields. The LH is more accurate than the RH in encoding unattended syllables, as indicated by facilitation in the left but not right visual field and a greater frequency of identifiable intrusions into the left than right field. However, asymmetric encoding strategies are different for attended and unattended syllables.     

Perceptual grouping operates independently of attentional selection: Evidence from hemispatial neglect

To what extent can human observers process visual information that is not currently the focus of attention? We evaluated the extent to which unattended visual information (i.e., that which appears on the neglected side of space in individuals with hemispatial neglect) is perceptually organized and influences the perceptual processing of information on the attended side. To examine this, patients (and matched controls) judged whether successive, complex checkerboard stimuli (targets), presented entirely to their intact side of space, were the same or different. Concurrent with this demanding task, irrelevant distractor elements appeared on the unattended side and either changed or retained their perceptual grouping on successive displays, independently of changes in the ipsilesional task-relevant target. Changes in the grouping of the unattended task-irrelevant distractor elements produced congruency effects on the attended target-change judgment to the same extent in the neglect patients as in the control participants, and this was true even in those patients with severe attentional deficits. These results suggest that some perceptual processes, such as grouping, can operate in the absence of attention.     

Attention level and negative priming in hierarchical patterns1

Abstract: This study explored object processing associated with attention level dependent on task, using a paradigm of negative priming. Participants were required to identify target characters that appeared at either the global or local level in hierarchically structured patterns. Two experiments were conducted to examine how the global and local characters were processed in the attended and unattended levels. In the results of Experiment 1, where stimuli were presented for 10 ms, negative priming was observed in a local‐directed task, but not in a global‐directed one. These results suggested that the inhibition of local characters in the unattended level did not occur during global attention. The results of Experiment 2 revealed that negative priming was observed in both global‐ and local‐directed tasks in the 500 ms presentation, showing that inhibition in the unattended level occurred. As a result, the exposure duration influences inhibition in the unattended, especially the local level. At short exposure duration, the local characters are not inhibited when one directs attention to the global characters, whereas these are inhibited at long exposure duration.     

Semantic processing of unattended text during selective reading: how the eyes see it

Subjects were instructed to read and comprehend a target (attended) passage while eye movements were recorded. A second (unattended) passage was also present, with attended and unattended passages occupying alternating lines of text. Subsequent multiple-choice questions showed acquisition of semantic information from attended and unattended text. However, a detailed examination of eye-fixation records showed that readers occasionally fixated unattended text, indicating the presence of shifts of visual attention to unattended text. When fixations of unattended text were excluded, there was no longer any indication that readers obtained useful semantic information from unattended text.     

Using inattentional blindness as an operational definition of unattended: The case of surface completion

Studying inattentional processing is made difficult by the fact that measuring it often results in observers attending to the stimuli in question. Here it is suggested that inattentional blindness—the lack of awareness of stimuli that appear in unattended regions of the visual field—be used as an operational definition of unattended. Separate online measures, taken while the stimuli are still present, can then be used to probe specific aspects of processing. Applying this method to the perceptual completion of partial surfaces, an online measure of modal and amodal completion was developed, and then used within an experiment in which inattentional blindness to the surfaces was assessed. The results indicated that surface completion can be engaged by unattended stimuli. More generally, the study illustrates the usefulness of this approach for probing what processing does and does not occur for stimuli that appear in unattended regions of the visual field.     

Context use by right-hemisphere-damaged individuals under a compressed speech condition

The effect of increased processing demands on context use by RHD individuals was examined using a word-monitoring task. Subjects were required to monitor for a target word in sentences that were either normal, semantically anomalous, or both syntactically and semantically anomalous. Stimuli were presented at two rates of speech--normal and compressed to 70% of normal. Contrary to expectations, the RHD group performed similar to normals in demonstrating an effect of context at both rates of speech. Results are discussed relative to recent studies of normal brain functioning that suggest that the involvement of the LH versus the RH in context use depends upon the type of contextual information being processed.