Memory reloaded: Memory load effects in the attentional blink

When two targets are presented in rapid succession, identification of the first is nearly perfect, while identification of the second is impaired when it follows the first by less than about 700 ms. According to bottleneck models, this attentional blink (AB) occurs because the second target is unable to gain access to capacity-limited working memory processes already occupied by the first target. Evidence for this hypothesis, however, has been mixed, with recent reports suggesting that increasing working memory load does not affect the AB. The present paper explores possible reasons for failures to find a link between memory load and the AB and shows that a reliable effect of load can be obtained when the item directly after T1 (Target 1) is omitted. This finding provides initial evidence that working memory load can influence the AB and additional evidence for a link between T1 processing time and the AB predicted by bottleneck models.     

Investigating the nature and time-course of the modality shift effect between vision and touch

It is well known that stimuli grab attention to their location, but do they also grab attention to their sensory modality? The modality shift effect (MSE), the observation that responding to a stimulus leads to reaction time benefits for subsequent stimuli in the same modality, suggests that this may be the case. If noninformative cue stimuli, which do not require a response, also lead to benefits for their modality, this would suggest that the effect is automatic. We investigated the time-course of the visuotactile MSE and the difference between the effects of cues and targets. In Experiment 1, when visual and tactile tasks and stimulus locations were matched, uninformative cues did not lead to reaction time benefits for targets in the same modality. However, the modality of the previous target led to a significant MSE. Only stimuli that require a response, therefore, appear to lead to reaction time benefits for their modality. In Experiment 2, increasing attention to the cue stimuli attenuated the effect of the previous target, but the cues still did not lead to a MSE. In Experiment 3, a MSE was demonstrated between successive targets, and this effect decreased with increasing intertrial intervals. Overall, these studies demonstrate how cue- and target-induced effects interact and suggest that modalities do not automatically capture attention as locations do; rather, the MSE is more similar to other task repetition effects.     

Inhibition from blinked category labels: Combining the attentional blink and the semantic priming paradigm

In the present experiment we combined the attentional blink and the semantic priming paradigm. We used category labels as primes and category exemplars as targets. The prime stimuli were embedded into a rapid serial visual presentation (RSVP) stream and presented at varying positions after a to-be-identified stimulus, albeit the stimulus–onset asynchrony between primes and targets remained constant throughout the experiment. As a result, participants’ prime awareness was reduced in some trials although the prime duration was always at levels usually considered to elicit awareness (60 ms). After each RSVP there was a forced choice discrimination test to assess participants’ prime awareness. When subjects could not identify the prime stimuli we observed slower responses to related as compared to unrelated targets. This result confirms results found with repeated masked primes. However, whereas former studies assessed unawareness rather coarsely at the level of individual participants, here unawareness was tested on a trial-by-trial basis.     

Self-relevance increases the irrelevant sound effect: Attentional disruption by one's own name

Memory performance is severely disrupted when task-irrelevant sound is played during item presentation or in a retention interval. Working memory models make contrasting assumptions on whether the semantic content of the auditory distractors modulates the irrelevant sound effect. In the present study, participants made more errors in serial recall when they had to ignore sentences containing their own name as opposed to that of a yoked-control partner. These results are only consistent with working memory models that allow for attentional processes to play a role in the explanation of the irrelevant sound effect. With repeated presentation the disruptive effect of one's own name decreased, whereas the disruptive effect of the auditory distractors in the control condition remained constant. The latter finding is most consistent with the duplex model of auditory attention, which assumes that the irrelevant sound effect is primarily caused by automatic interference of acoustic distractor features, but at the same time allows for a disruption of encoding due to attentional capture by unexpected deviants. However, to explain the present results, the mechanism responsible for the attentional capture has to be extended to highly (self-)relevant auditory distractors.     

Does low perceptual load enable capture by colour singletons?

There is considerable debate as to whether colour singletons can capture attention in a stimulus-driven manner. In this study, we explore one potential capture enabling condition—low perceptual load. To test this hypothesis, we manipulated perceptual load in a flanker task in which flanking letters sometimes were colour singletons. If low load enhances capture by colour singletons, then colour singletons should produce an especially large increase in overall reaction times and in flanker–target compatibility effects. Neither of these predictions was confirmed in any of the four experiments reported here, although we did replicate the classic load effects from previous studies. These experiments indicate that although perceptual load does strongly modulate overall performance, it does not facilitate capture by colour singletons. This finding contrasts sharply with findings from other types of salient stimuli (abrupt onsets and moving objects). Implications for theories of attentional capture will be discussed.     

Bilingualism aids conflict resolution: evidence from the ANT task

The need of bilinguals to continuously control two languages during speech production may exert general effects on their attentional networks. To explore this issue we compared the performance of bilinguals and monolinguals in the attentional network task (ANT) developed by Fan et al. [Fan, J., McCandliss, B.D. Sommer, T., Raz, A., Posner, M.I. (2002). Testing the efficiency and independence of attentional networks. Journal of Cognitive Neuroscience, 14, 340-347]. This task is supposed to tap into three different attentional networks: alerting, orienting and executive control. The results revealed that bilingual participants were not only faster in performing the task, but also more efficient in the alerting and executive control networks. In particular, bilinguals were aided more by the presentation of an alerting cue, and were also better at resolving conflicting information. Furthermore, bilinguals experienced a reduced switching cost between the different type of trials compared to monolinguals. These results show that bilingualism exerts an influence in the attainment of efficient attentional mechanisms by young adults that are supposed to be at the peak of their attentional capabilities.     

Deployment dynamics of hypnotic anger modulation

To understand the role that attention plays in the deployment timeline of hypnotic anger modulation, we composed an Attentional Blink paradigm where the first and second targets were faces, expressing neutral or angry emotions. We then suppressed the salience of angry faces through a “hypnotic numbing” suggestion. We found that hypnotic suggestion only attenuated the emotional salience of the second target (T2). By implementing drift-diffusion decision modelling, we also found that hypnotic suggestion mainly affected decision thresholds. These findings suggest that hypnotic numbing resulted from belated changes in response strategy. Interestingly, a contrast against non-hypnotized participants revealed that the numbing suggestion had the instruction-like feature of incorporating emotional valence into the attentional task-set. Together, our results portray hypnotic anger modulation as a two-tiered process: first, hypnotic suggestion alters the attentional task-set; second, provided processing and response preparation are not interrupted, a hypnotizability-dependent response based on said altered task-set is produced through late cognitive control strategies.     

Automatic shifts of attention in the Dimensional Change Card Sort task: Subtle changes in task materials lead to flexible switching

Two experiments tested a hypothesis that reducing demands on executive control in a Dimensional Change Card Sort task will lead to improved performance in 3-year-olds. In Experiment 1, the shape dimension was represented by two dissimilar values (stars and flowers), and the color dimension was represented by two similar values (red and pink). This configuration of stimuli rendered shape more salient than color. In Experiment 2, attentional weights of each dimension value were manipulated by using two versus four values to represent the dimensions of shape and color. The results indicated that increasing saliency of the postswitch dimension (Experiment 1) and reducing attentional weights of individual dimension values (Experiment 2) lead to a marked improvement in the postswitch sorting accuracy in 3-year-olds.     

Attentional capture by items that match episodic long-term memory representations

A remarkable ability of the human visual system is the implementation of attentional control settings (ACSs) that govern what stimuli capture or hold attention. We provide evidence that ACSs can be specified by episodic long-term memory representations. In all experiments, participants memorized 30 images of objects that they then monitored for in an attention task, inducing an episodic-based ACS. In Experiments 1a and 1b, only studied cues in a cueing task captured attention. We confirmed these cueing effects reflect capture by testing for inhibition of return in Experiment 2a, and controlled for perceptual masking by cues in Experiment 2b. In Experiment 3 we determined that ACSs are specifically supported by episodic retrieval, by dividing studied images into two sets and designating one as the targets in a rapid serial visual presentation task: Only target-set matching distractors produced a spatial blink (captured attention). These results extend our understanding of the representations specifying ACSs.     

Selectively ignoring locations does not modulate contingent involuntary orienting,but selectively attending does

Attending to a location in the visual field facilitates processing of objects in that location, and numerous studies have revealed processing benefits by precuing target locations. Recent studies have also demonstrated that precuing a location to ignore reduces distraction by items in that location; however, precuing a feature (colour) to ignore increases distractor interference, at least before a template for rejection is established. Thus, locations, not features, can be selectively ignored. The present study used a spatial cuing task to examine whether featurally-relevant items are selected when they appear in ignored locations. The results revealed contingent attentional capture by target-relevant cues (red cue when searching for red targets, but not for onset targets), even when the cue appeared in a location that was ignored. Importantly, this was equivalent to contingent capture elicited by cues in non-ignored locations. However, when observers were precued to the target location, contingent capture was largely eliminated. The results suggest salient items with target-relevant features are selected from selectively ignored locations, but focusing attention onto a location can preclude capture by salient and target-relevant items.