Attentional disengagement in adults with Williams syndrome

Williams syndrome (WS) is a neurodevelopmental disorder characterized by a distinctive behavioral and cognitive profile, including widespread problems with attention. However, the specific nature of their attentional difficulties, such as inappropriate attentional allocation and/or poor attentional disengagement abilities, has yet to be elucidated. Furthermore, it is unknown if there is an underlying difficulty with the temporal dynamics of attention in WS or if their attentional difficulties are task-dependent, because previous studies have examined attention in established areas of deficit and atypicality (specifically, visuospatial and face processing). In this study, we examined attentional processing in 14 adults with WS (20–59 years) and 17 typically developing controls (19–39 years) using an attentional blink (AB) paradigm. The AB is the decreased ability to detect a second target when it is presented in close proximity to an initial target. Overall, adults with WS had an AB that was prolonged in duration, but no different in magnitude, compared with typically developing control participants. AB performance was not explained by IQ, working memory, or processing speed in either group. Thus, results suggest that the attention problems in WS are primarily due to general attentional disengagement difficulties rather than inappropriate attentional allocation.     

An attentional blink for sequentially presented targets: Evidence in favor of resource depletion accounts

Several accounts of the attentional blink (AB) have postulated that this dual-target deficit occurs because of limited-capacity attentional resources being devoted to processing the first target at the expense of the second (resource depletion accounts; e.g., Chun & Potter, 1995). Recent accounts have challenged this model (e.g., Di Lollo, Kawahara, Ghorashi, & Enns, 2005; Olivers, van der Stigchel, & Hulleman, 2007), proposing instead that the AB occurs because of subjects’ inability to maintain appropriate levels of attentional control when targets are separated by distractors. Accordingly, the AB is eliminated when three targets from the same attentional set are presented sequentially in a rapid serial visual presentation (RSVP) stream. However, under such conditions poorer identification of the first target is typically observed, hinting at a potential trade-off between the first and subsequent target performances. Consistent with this hypothesis, the present study shows that an AB is observed for successive targets from the same attentional set in an RSVP stream when the first target powerfully captures attention. These results suggest that resource depletion contributes significantly to the AB.     

How to keep attention from straying: Get engaged!

Previous research has suggested that the involuntary allocation of spatial attention to salient, irrelevant stimuli (i.e., attentional capture) is prevented when attention is in a focused state (e.g., Yantis & Jonides, 1990). Recent work has suggested that although focused attention may be necessary to prevent attentional capture by irrelevant stimuli, it is not sufficient (e.g., Folk, Leber, & Egeth, 2002). The present experiments provide evidence that attentional engagement, rather than attentional focusing, prevents capture. Observers performed a rapid serial visual presentation task in which they were asked to identify a target letter defined by color. Peripheral distractors that shared the color of the target produced evidence of attentional capture. This effect was completely eliminated, however, when the peripheral distractor was preceded by a central distractor designed to engage attention on the stream. It is concluded that attentional engagement serves to lock out capture by irrelevant, salient stimuli.     

Hold it! Memory affects attentional dwell time

The allocation of attention, including the initial orienting and the subsequent dwell time, is affected by several bottom-up and top-down factors. How item memory affects these processes, however, remains unclear. Here, we investigated whether item memory affects attentional dwell time by using a modified version of the attentional blink (AB) paradigm. Across four experiments, our results revealed that the AB was significantly affected by memory status (novel vs. old), but critically, this effect depended on the ongoing memory context. Specifically, items that were unique in terms of memory status demanded more resources, as measured by a protracted AB. The present findings suggest that a more comprehensive understanding of memory’s effects on attention can be obtained by accounting for an item’s memorial context, as well as its individual item memory strength. Our results provide new evidence that item memory and memory context play a significant role in the temporal allocation of attention.     

The effect of similarity between elemental stimuli and compounds in olfactory patterning discriminations

We studied the ability of honeybees to discriminate between single odorants and binary olfactory mixtures. We analyzed the effect of the number of common elements between these two stimulus classes on olfactory discrimination. We used olfactory conditioning of the honeybees' proboscis extension reflex (PER), a paradigm in which odors can be associated with a reinforcement of sucrose solution. Bees were asked to discriminate reinforced from nonreinforced olfactory stimuli. They were trained with two elemental odors (A and B) versus a binary olfactory mixture. The mixture was either AB (group 2CE, two common elements), AC (group 1CE, one common element A), or CD (group 0CE, no common element). Three groups followed a positive patterning schedule (mixture reinforced and elements nonreinforced: groups 2CE+, 1CE+, and 0CE+) and three other groups a negative patterning schedule (mixture nonreinforced and elements reinforced: groups 2CE-, 1CE-, and 0CE-). We showed that a reduction of similarity (number of common elements) between elemental odors and compounds enhanced the ability to discriminate elements from compounds and that the kind of compound processing used by the bees supports theories that assume nonelemental compound processing (i.e., that exclude the mere summation of the elemental associative strengths upon compound presentation).     

An exploratory investigation of coffee and lemon scents and odor identification

Fragrance sellers often provide coffee beans to their customers as a "nasal palate cleanser," to reduce the effects of olfactory adaptation and habituation. To test this idea, college students smelled three fragrances multiple times, rating odors each time. After completing nine trials, participants sniffed coffee beans, lemon slices, or plain air. Participants then indicated which of four presented fragrances had not been previously smelled; Coffee beans did not yield better performance than lemon slices or air.     

Attention is biased to near surfaces

It is thought that attention is allocated to figural items over adjacent ground stimuli. It is unclear which attribute of figures drives any previously observed attentional effects (e.g., nearness or shapedness). Moreover, it is unclear whether previous attentional effects are automatic or strategy driven. In the present series of experiments, we tested whether attention is allocated to the nearer of two surfaces under condition where near/far was not confounded with shaped/shapelessness. Using a temporal order judgment paradigm, in the first experiment, we showed that attention is allocated to the nearer of two surfaces. Furthermore, by using the stimuli themselves as the temporal order probe in Experiment 2, we found that this effect is independent of previous attentional allocation across the visual field. A third experiment ruled out the possibility that lateral inhibition by the pretarget backdrop was responsible for attentional bias toward near surfaces. Overall, our results converge to show that near surfaces attract attention.     

Individual differences in dispositional focus of attention predict attentional blink magnitude

When identifying two targets presented in a rapid serial visual presentation stream, one’s accuracy on the second target is reduced if it is presented shortly (within 500 msec) after the first target—an attentional blink (AB). Individuals differ greatly in the size of their AB. One way to learn about the AB is to understand what underlies these individual differences. Recent studies have suggested that when a broadened or diffused attentional state is induced, the AB deficit can be attenuated. The present study examined whether natural (dispositional) individual differences in focus and diffusion of attention as assessed by the global/local task could predict performance on the AB task. Performance that was consistent with diffusion correlated negatively with AB size, and performance that was consistent with focusing correlated positively with AB size, showing that dispositional focus and diffusion of attention can predict individual differences in the AB. These findings are consistent with the Olivers and Nieuwenhuis (2006) overinvestment hypothesis.     

Alerting enhances target identification but does not affect the magnitude of the attentional blink

Identification of the second of two targets is impaired when presented less than about 500 ms after the first. The magnitude of this attentional blink (AB) is known to be modulated by tonic factors (e.g., observer's state of relaxation). The present work examined the effects of a phasic change in observer's state brought about by an alerting stimulus (an aggregate of faint rings) presented in temporal proximity to either letter-target inserted in a temporal stream (RSVP) of digit distractors. In four experiments, identification accuracy of each target was substantially improved by presenting the alerting stimulus either in the target's frame or in the preceding RSVP frame. However, alerting did not modulate the magnitude of the AB. The appearance of an alerting effect on the AB in Experiment 1 was ascribed to a ceiling effect in Experiment 2. Experiment 3 ruled out endogenous temporal cueing effects; Experiment 4 examined the temporal gradient of alerting. Independence of the alerting and AB effects suggests that the alerting stimuli and the letter targets may be processed along distinct visual pathways.     

Masking T1 difficulty: processing time and the attenional blink

When observers are presented with 2 targets in rapid succession, identification of the 1st is highly accurate, whereas identification of the 2nd is impaired at brief intertarget intervals (i.e., 200-500 ms). This 2nd-target deficit is known as the attentional blink (AB). According to bottleneck models, the AB arises because attending to the 1st target delays allocation of attention to the 2nd target. Thus, these models predict that increasing 1st-target processing time will increase the magnitude of the AB. Previous tests of this prediction have yielded mixed results. The present work suggests that one factor contributing to this uncertainty is masking of the 1st target: When this mask is omitted, processing time and AB magnitude are reliably related. These findings clarify the role of 1st-target masking in the AB and support the validity of the bottleneck account.     

Attentional SNARC: there's something special about numbers (let us count the ways)

We report a study that examines whether the presentation of irrelevant, ordinal information at central fixation interacts with the allocation of attention beyond fixation. Previous research has demonstrated that number perception influences the allocation of spatial attention, such that the presentation of a spatially nonpredictive number at fixation results in attention being allocated to the left when the central number is low (e.g., 1), and attention being allocated to the right when the central number is high (e.g., 9). Here, we examine whether this attentional SNARC effect (spatial numerical association of response codes) generalizes to other ordinal sequences: letters, days, and months. Though we replicate the attentional SNARC we find that this effect is number-specific, unless participants are required to process the cue in an order-relevant fashion. This discovery of number-specificity has important implications both for the functional separation between SNARC and attention-SNARC effects, as well as lending support to recent theories regarding the specificity of a shared neural architecture between numbers and visuospatial attention.     

Distraction and the auditory attentional blink

When two target stimuli (T1 and T2) are presented in close succession within a stimulus sequence, detection or discrimination performance for T2 is often impaired; this phenomenon is called the attentional blink (AB). Growing evidence suggests that the AB is present not only for visual, but also for auditory stimuli. Because sounds have a strong potential to attract attention when they are presented after longer silent intervals or in a sequence from which they stand out because of their rare or novel physical features, it seems possible that the involuntary and excessive allocation of attention to T1 (distraction) may contribute to the AB. By varying the saliency of T1, we showed that distraction does contribute to the auditory AB effect, but the contribution is short-lived: Only stimuli immediately following T1 are affected.     

The attentional blink: Resource depletion or temporary loss of control?

Identification of the second of two targets is impaired if it is presented less than about 500 ms after the first. Theoretical accounts of this second-target deficit, known as attentional blink (AB), have relied on some form of limited attentional resource that is allocated to the leading target at the expense of the trailing target. Three experiments in the present study reveal a failure of resource-limitation accounts to explain why the AB is absent when the targets consist of a stream of three items belonging to the same category (e.g., letters or digits). The AB is reinstated, however, if an item from a different category is inserted in the target string. This result, and all major results in the AB literature, is explained by the hypothesis that the AB arises from a temporary loss of control over the prevailing attentional set. This lapse in control renders the observer vulnerable to an exogenously-triggered switch in attentional set.     

Differences in attentional involvement underlying the perception of distinctive and typical faces

Differences in human faces can be evaluated along a continuum that ranges from 'distinctive' to 'typical.' We examined processing differences between distinctive and typical faces by two attentional tasks that induce attentional blink (AB). Given that AB is believed to reflect temporal or capacity limits of attention, stimuli that survive AB are believed to be associated with greater processing efficiency. In a change-detection task, participants were required to detect changes in the two pairs of faces that were presented in rapid succession. Changes involving the distinctive face of a pair were more likely to be detected than those involving a typical face. In a face-identification task, distinctive faces embedded in a rapid serial visual presentation (RSVP) stream were identified with a greater accuracy than typical faces. Together, our results suggest that distinctive faces are associated with greater processing efficiency and may be explained in terms of perceptual salience, a stimulus dimension known to attract attention.     

The Influence of Attentional State and Stimulus Characteristics on Infant Distractibility

To examine the interactive effects of stimulus characteristics and attentional state on the allocation of attention in infancy, we presented distractor stimuli to 7-month-old infants while they explored novel objects, and we measured the infants' latencies to turn toward the distractors. Two different types of distractor stimuli (single-tone vs. alternating-tone) were used. For each stimulus presentation we determined whether the infant was engaged in focused or casual attention toward the novel object before the distractor was presented. As in previous studies, we found that distraction latencies were shorter during casual attention than during focused attention, but this effect was found to interact with the type of distractor stimulus. There was no effect of attentional state for the alternating-tone distractor, whereas there was an effect of attentional state for the single-tone distractor. Thus, external stimulus variables interact with an infant's internal attentional state to determine the moment-by-moment allocation of attention.     

Effects of lavender aroma on sleep quality in healthy Japanese students

This single-blind randomized study investigated the effectiveness of lavender aroma on quality of sleep in healthy Japanese students. The data of seven participants (2 men, 5 women) in the intervention group and eight participants (3 men, 5 women) in the control group were analyzed (M age = 19.0 yr., SD = 0.9). The total procedure comprised 3 days for pre-intervention assessment, 5 days for the intervention, and 3 days for post-intervention assessment. Lavender exposure was compared with the absence of lavender (control). Information regarding the relaxing effect of aromas was provided to examine expectancy effects. Results showed that lavender aroma improved sleepiness at awakening after the intervention. Sex differences and daily variation in quality of sleep during the intervention period were not observed. The findings suggest that nighttime exposure to lavender aroma relieves sleepiness at awakening.     

Negative numbers eliminate,but do not reverse,the attentional SNARC effect

Three experiments are reported examining whether the presentation of irrelevant negative numbers at central fixation interacts with attentional orienting beyond fixation. It has been previously shown that number perception influences spatial attention, with the presentation of spatially nonpredictive numbers resulting in the allocation of attention to the left when the number is low (e.g., 1 or 2) and to the right when the number is high (e.g., 8 or 9). In the present experiment, it is examined whether this attentional spatial numerical association of response codes (SNARC) effect is influenced by the presentation of negative numbers, which should have spatial properties that are in direct opposition to their positive counterparts (e.g., −1 or −2 would be considered high numbers relative to −8 or −9, which would be considered low numbers). Though the presentation of negative numbers does not lead to a reversal of the attentional SNARC effect, it does lead to an elimination of the effect, providing insight into how the attentional SNARC effect develops.     

The “beam of darkness”: Spreading of the attentional blink within and between objects

When two targets (T1 and T2) are inserted into a rapid serial visual presentation (RSVP) stream of nontargets, observers are impaired at identifying T2 when it is presented within half a second after T1. This transient drop in performance, or attentional blink (AB), has been attributed to a temporary unavailability of task-critical processing resources. In the present study, we investigated how object-based attention modulates the AB, by presenting four synchronized RSVP streams in the corners of two rectangular bars (e.g., one above and one below fixation). The results from four experiments revealed that the AB increased within short temporal lags (of up to ～400 msec) when T2 was presented on the same, rather than a different, bar as T1 (with T1–T2 spatial distance controlled for). Thus, the AB is seen to spread across entire object groupings, suggesting that the spatiotemporal resolution of attention is modulated by global-object information.     

Olfactory test performance and its relationship with the perceived location of odors

Odors are generally perceived as arising via the nose when sniffed and as part of an orally located flavor during ingestion. The perceived location of an odor may in part be an attentional phenomenon, with concurrent oral stimulation occurring at the expense of access to the olfactory channel. Two predictions were derived from this account: (a) tasks dependent on a capacity to attend to the olfactory channel--odor discrimination and naming--should be adversely affected by oral localization; and (b) tasks not dependent upon a capacity to attend--incidental learning/recognition memory--should not. Using a procedure to generate oral localization, in which odors were presented via the nose with concurrent oral stimulation (sucrose, a viscous fluid or water), greater reported oral localization was associated with poorer odor discrimination and naming, but not with recognition memory performance. These results support the notion that attentional processes contribute to oral localization of odors by reducing the capacity to attend to the olfactory channel.