Contribution of speech rhythm to understanding speech in noisy conditions: Further test of a selective entrainment hypothesis.

Previous work by McAuley et al. Attention, Perception, & Psychophysics, 82, 3222-3233, (2020), Attention, Perception & Psychophysics, 83, 2229-2240, (2021) showed that disruption of the natural rhythm of target (attended) speech worsens speech recognition in the presence of competing background speech or noise (a target-rhythm effect), while disruption of background speech rhythm improves target recognition (a background-rhythm effect). While these results were interpreted as support for the role of rhythmic regularities in facilitating target-speech recognition amidst competing backgrounds (in line with a selective entrainment hypothesis), questions remain about the factors that contribute to the target-rhythm effect. Experiment 1 ruled out the possibility that the target-rhythm effect relies on a decrease in intelligibility of the rhythm-altered keywords. Sentences from the Coordinate Response Measure (CRM) paradigm were presented with a background of speech-shaped noise, and the rhythm of the initial portion of these target sentences (the target rhythmic context) was altered while critically leaving the target Color and Number keywords intact. Results showed a target-rhythm effect, evidenced by poorer keyword recognition when the target rhythmic context was altered, despite the absence of rhythmic manipulation of the keywords. Experiment 2 examined the influence of the relative onset asynchrony between target and background keywords. Results showed a significant target-rhythm effect that was independent of the effect of target-background keyword onset asynchrony. Experiment 3 provided additional support for the selective entrainment hypothesis by replicating the target-rhythm effect with a set of speech materials that were less rhythmically constrained than the CRM sentences.

Does preparation help to switch auditory attention between simultaneous voices: Effects of switch probability and prevalence of conflict.

Switching auditory attention to one of two (or more) simultaneous voices incurs a substantial performance overhead. Whether/when this voice 'switch cost' reduces when the listener has opportunity to prepare in silence is not clear-the findings on the effect of preparation on the switch cost range from (near) null to substantial. We sought to determine which factors are crucial for encouraging preparation and detecting its effect on the switch cost in a paradigm where participants categorized the number spoken by one of two simultaneous voices; the target voice, which changed unpredictably, was specified by a visual cue depicting the target's gender. First, we manipulated the probability of a voice switch. When 25% of trials were switches, increasing the preparation interval (50/800/1,400 ms) resulted in substantial (~50%) reduction in switch cost. No reduction was observed when 75% of trials were switches. Second, we examined the relative prevalence of low-conflict, 'congruent' trials (where the numbers spoken by the two voices were mapped onto the same response) and high-conflict, 'incongruent' trials (where the voices afforded different responses). 'Conflict prevalence' had a strong effect on selectivity-the incongruent-congruent difference ('congruence effect') was reduced in the 66%-incongruent condition relative to the 66%-congruent condition-but conflict prevalence did not discernibly interact with preparation and its effect on the switch cost. Thus, conditions where switches of target voice are relatively rare are especially conducive to preparation, possibly because attention is committed more strongly to (and/or disengaged less rapidly from) the perceptual features of target voice.

Retrospective cue benefits in visual working memory are limited to a single location at a time.

Working memory (WM) performance can be improved by an informative cue presented during storage. This effect, termed a retrocue benefit, can be used to study limits on how human observers prioritize information stored in WM for behavioral output. There is disagreement about whether retrocue benefits extend to multiple WM locations. Here, we hypothesized that multiple retrocues may improve some aspects of memory performance (e.g., a reduction in random guessing) while worsening others (e.g., an increase in the probability of reporting a feature presented at a non-probed location). We tested this possibility in three experiments. Participants remembered arrays of four orientations or colors over a brief delay, and spatial retrocues instructed participants to prioritize zero, one, two, or all four remembered orientations for possible report. At the end of the trial, participants recalled the orientation that appeared at one location. The results of this study revealed that participants' recall errors were lower during cue-one relative to cue-two and cue-four trials, and this benefit was driven primarily by a reduction in random guessing during cue-one trials. We found no evidence suggesting that multiple spatial cues (i.e., during cue-two trials) induced a trade-off between memory precision, random guessing, and non-target reports compared to neutral trials (i.e., cue-zero or cue-four). Thus, cuing participants to prioritize information appearing at multiple unique spatial positions led to no improvement in memory performance compared to neutral or no-cue trials, providing additional support for the view that retrocue benefits on WM performance are limited to a single spatial location at a time.

Spatial task relevance modulates value-driven attentional capture.

Attention tends to be attracted to visual features previously associated with reward. To date, nearly all existing studies examined value-associated stimuli at or near potential target locations, making such locations meaningful to inspect. The present experiments examined whether the attentional priority of a value-associated stimulus depends on its location-wise task relevance. In three experiments we used an RSVP task to compare the attentional demands of a value-associated peripheral distractor to that of a distractor associated with the top-down search goal. At a peripheral location that could never contain the target, a value-associated color did not capture attention. In contrast, at the same location, a distractor in a goal-matching color did capture attention. The results show that value-associated stimuli lose their attentional priority at task-irrelevant locations, in contrast to other types of stimuli that capture attention.

Perceptual and cognitive processes in augmented reality - comparison between binocular and monocular presentations.

In the present study, we investigated the difference between monocular augmented reality (AR) and binocular AR in terms of perception and cognition by using a task that combines the flanker task with the oddball task. A right- or left-facing arrowhead was presented as a central stimulus at the central vision, and participants were instructed to press a key only when the direction in which the arrowhead faced was a target. In a small number of trials, arrowheads that were facing in the same or opposite direction (flanker stimuli) were presented beside the central stimulus binocularly or monocularly as an AR image. In the binocular condition, the flanker stimuli were presented to both eyes, and, in the monocular condition, only to the dominant eye. The results revealed that participants could respond faster in the binocular condition than in the monocular one; however, only when the flanker stimuli were in the opposite direction was the response faster in the monocular condition. Moreover, the results of event-related brain potentials (ERPs) showed that all stimuli were processed in both the monocular and the binocular conditions in the perceptual stage; however, the influence of the flanker stimuli was attenuated in the monocular condition in the cognitive stage. The influence of flanker stimuli might be more unstable in the monocular condition than in the binocular condition, but more precise examination should be conducted in a future study.

What is cued by faces in the face-based context-specific proportion congruent manipulation?

In a typical context-specific proportion congruent manipulation, participants are presented with Stroop stimuli in one of two contexts. In one context, stimuli are mostly incongruent. In the other context, stimuli are mostly congruent. Despite task-wide instructions to ignore the word and to name the color in which the word appears, the size of the congruency effect varies as a function of context. Specifically, the size of the congruency effect is reduced for the mostly incongruent relative to the mostly congruent context. The purpose of the current series of experiments is to explore the mechanisms underlying this context-specific proportion congruent (CSPC) effect when faces are used as the context. Existing manipulations have reported a face-based CSPC effect, however the results of these studies are confounded with contingency learning biases leaving an open question as to what processes faces serve to cue. In the four experiments reported here both inducer (contingency-biased) and diagnostic (contingency-unbiased) stimuli were included in a face-based context level manipulation. Across four experiments, a face-based CSPC effect is observed for inducer but not diagnostic stimuli, suggesting that this effect is driven by participants learning context + stimulus associations.

Attentional tracking takes place over perceived rather than veridical positions.

Illusions can induce striking differences between perception and retinal input. For instance, a static Gabor with a moving internal texture appears to be shifted in the direction of its internal motion, a shift that increases dramatically when the Gabor itself is also in motion. Here, we ask whether attention operates on the perceptual or physical location of this stimulus. To do so, we generated an attentional tracking task where participants (N = 15) had to keep track of a single target among three Gabors that rotated around a common center in the periphery. During tracking, the illusion was used to make three Gabors appear either shifted away from or toward one another while maintaining the same physical separation. Because tracking performance depends in part on target to distractor spacing, if attention selects targets from perceived positions, performance should be better when the Gabors appear further apart and worse when they appear closer together. We find that tracking performance is superior with greater perceived separation, implying that attentional tracking operates over perceived rather than physical positions.

Uncertainty modulates value-driven attentional capture.

The majority of previous studies on the value modulation of attention have shown that the magnitude of value-driven attentional bias correlates with the strength of reward association. However, relatively little is known about how uncertainty affects value-based attentional bias. We investigated whether attentional capture by previously rewarded stimuli is modulated by the uncertainty of the learned value without the influence of the strength of reward association. Participants were instructed to identify the line orientation in the target color circle. Importantly, each target color was associated with a different level of uncertainty by tuning the variation in reward delivery (Experiment 1) or reward magnitude (Experiment 2). Attentional interference for uncertainty-related distractors was greater than that for certainty distractors in Experiments 1 and 2. In addition, uncertainty-induced attentional bias disappeared earlier than attentional bias for certainty. The study demonstrated that uncertainty modulates value-based attentional capture in terms of strength and persistence, even when the effect of expected value remains constant.

Distractor probabilities modulate flanker task performance.

Expectations about upcoming events help humans to effectively filter out potential distractors and respond more efficiently to task-relevant inputs. While previous work has emphasized the role of expectations about task-relevant inputs, less is known about the role that expectations play in suppressing specific distractors. To address this question, we manipulated the probabilities of different flanker configurations in the Eriksen flanker task. Across four studies, we found robust evidence for sensitivity to the probability of flankers, with an approximately logarithmic relationship between the likelihood of a particular flanker configuration and the accuracy of subjects' responses. Subjects were also sensitive to length of runs of repeated targets, but minimally sensitive to length of runs of repeated flankers. Two studies used chevron stimuli, and two used letters (confirming that results generalize with greater dissimilarity between stimuli). Expanding the set of stimuli (thus reducing the dominance of any one exemplar) eliminated the effect. Our findings suggest that expectations about distractors form in response to statistical regularities at multiple timescales, and that their effects are strongest when stimuli are geometrically similar and subjects are able to respond to trials quickly. Unexpected distractors could disrupt performance, most likely via a form of attentional capture. This work demonstrates how expectations can influence attention in complex cognitive settings, and illuminates the multiple, nested factors that contribute.

Target-flanker similarity effects reflect image segmentation not perceptual grouping.

When responding to the identity of a visual target, nearby stimuli (flankers) that are associated with the same response as the target cause faster and more accurate responding than flankers that are associated with different responses. Because this flanker-congruence effect (FCE) decreases with increasing target-flanker separation, it was thought to reflect limited precision of spatial selection mechanisms. Later studies, however, showed that FCEs are larger when the target and flankers are the same color compared to when they are different colors. This led to the group selection hypothesis, which states that flankers are perceptually grouped with the target and are obligatorily selected along with it, regardless of spatial separation. An alternative hypothesis, the image segmentation hypothesis, states that feature differences facilitate the segmentation of visual information into relevant and irrelevant parts, thereby mitigating the limitations of spatial precision of selection mechanisms. We test between these hypotheses using a design in which targets and flankers are grouped or not grouped, while holding feature differences in the stimulus constant. Contrary to earlier results, we found that same-colored flankers do not yield larger FCEs than different-colored flankers when feature differences are held constant. We conclude that similarity effects on the FCE reflect differential support for image segmentation, on which selection depends, rather than the obligatory selection of perceptually grouped flankers and targets.

Eriksen's two-phase model of spatial selective attention: Physiological evidence of trial-mixing-dependent response inhibition.

The early work of Charles W. Eriksen and colleagues provided us with both the flanker task and the concepts of response competition and continuous flow. The model of the flanker task that Eriksen and colleagues developed also includes the idea that processing occurs in two phases and the specific claim that pro-active response inhibition is employed to prevent errors under certain conditions. We first replicated and extended the behavioral evidence that motivated this specific claim and then tested it using a variety of physiological measures. We verified the prediction of Eriksen's Two-Phase Model of Spatial Selective Attention using the lateralized readiness potential and contingent negative variation. We also clarified a detail of the model using electromyographic activity and response force. We note that this contribution of Charles W. Eriksen has not received the attention that it deserves and that several recent models might need to be revised in light of Eriksen's work.

Auditory attentional filter in the absence of masking noise.

Signals containing attended frequencies are facilitated while those with unexpected frequencies are suppressed by an auditory filtering process. The neurocognitive mechanism underlying the auditory attentional filter is, however, poorly understood. The olivocochlear bundle (OCB), a brainstem neural circuit that is part of the efferent system, has been suggested to be partly responsible for the filtering via its noise-dependent antimasking effect. The current study examined the role of the OCB in attentional filtering, particularly the validity of the antimasking hypothesis, by comparing attentional filters measured in quiet and in the presence of background noise in a group of normal-hearing listeners. Filters obtained in both conditions were comparable, suggesting that the presence of background noise is not crucial for attentional filter generation. In addition, comparison of frequency-specific changes of the cue-evoked enhancement component of filters in quiet and noise also did not reveal any major contribution of background noise to the cue effect. These findings argue against the involvement of an antimasking effect in the attentional process. Instead of the antimasking effect mediated via medial olivocochlear fibers, results from current and earlier studies can be explained by frequency-specific modulation of afferent spontaneous activity by lateral olivocochlear fibers. It is proposed that the activity of these lateral fibers could be driven by top-down cortical control via a noise-independent mechanism. SIGNIFICANCE: The neural basis for auditory attentional filter remains a fundamental but poorly understood area in auditory neuroscience. The efferent olivocochlear pathway that projects from the brainstem back to the cochlea has been suggested to mediate the attentional effect via its noise-dependent antimasking effect. The current study demonstrates that the filter generation is mostly independent of the background noise, and therefore is unlikely to be mediated by the olivocochlear brainstem reflex. It is proposed that the entire cortico-olivocochlear system might instead be used to alter the hearing sensitivity during focus attention via frequency-specific modulation of afferent spontaneous activity.

Modulation of compatibility effects in response to experience: Two tests of initial and sequential learning.

Attentional control is a key component of goal-directed behavior. Modulation of this control in response to the statistics of the environment allows for flexible processing or suppression of relevant and irrelevant items in the environment. Modulation occurs robustly in compatibility-based attentional tasks, where incompatibility-related slowing is reduced when incompatible events are likely (i.e., the proportion compatibility effect; PCE). The PCE implicates dynamic changes in the measured compatibility effects that are central to fields of study such as attention, executive functions, and cognitive control. In these fields, stability in compatibility effects are generally assumed, which may be problematic if individual or group differences in measured compatibility effects may arise from differences in statistical learning speed or magnitude. Further, the sequential nature of many studies may lead the learning of certain statistics to be inadvertently applied to future behaviors. Here, we report tests of learning the PCE across conditions of task statistics and sequential blocks. We then test for the influence of feedback on the development of the PCE. We find clear evidence for the PCE, but no conclusive evidence for its slow development through experience. Initial experience with more incompatible trials selectively mitigated performance decreases in a subsequent block. Despite the lack of behavioral changes associated with patterns of learning, systematic within-task changes in compatibility effects remain an important possible source of variation in a wide range of attention research.

Visual selection and response selection without effector selection in tasks with circular arrays.

Charles Eriksen and colleagues conducted influential visual-search experiments with circular arrays for which the responses were either vocal naming or unimanual left-right switch movements. These methods have the advantages of the stimuli being equidistant from a centered fixation point and allowing study of visual selection and response selection when effector selection is not required, as in the more typical case in which responses are key presses of distinct fingers. Other researchers have used similar spatial arrangements, but with aimed movements of the limb or of a mouse-controlled cursor to study effects of stimulus identification, visual search, spatial stimulus-response compatibility, response-effect compatibility, and practice/transfer in isolation and jointly. We systematically review studies in these areas that include visual selection and response selection and execution, and examine implications of their results for the role of effector selection. Also, we illustrate that as one moves from simpler to more complex tasks, the results are consistent with a basic information-processing framework in which stimulus identification and selection of a target response location are distinct from selecting, planning, and moving an effector to the targeted location.

In search of exogenous feature-based attention.

Visual attention prioritizes the processing of sensory information at specific spatial locations (spatial attention; SA) or with specific feature values (feature-based attention; FBA). SA is well characterized in terms of behavior, brain activity, and temporal dynamics-for both top-down (endogenous) and bottom-up (exogenous) spatial orienting. FBA has been thoroughly studied in terms of top-down endogenous orienting, but much less is known about the potential of bottom-up exogenous influences of FBA. Here, in four experiments, we adapted a procedure used in two previous studies that reported exogenous FBA effects, with the goal of replicating and expanding on these findings, especially regarding its temporal dynamics. Unlike the two previous studies, we did not find significant effects of exogenous FBA. This was true (1) whether accuracy or RT was prioritized as the main measure, (2) with precues presented peripherally or centrally, (3) with cue-to-stimulus ISIs of varying durations, (4) with four or eight possible target locations, (5) at different meridians, (6) with either brief or long stimulus presentations, (7) and with either fixation contingent or noncontingent stimulus displays. In the last experiment, a postexperiment participant questionnaire indicated that only a small subset of participants, who mistakenly believed the irrelevant color of the precue indicated which stimulus was the target, exhibited benefits for valid exogenous FBA precues. Overall, we conclude that with the protocol used in the studies reporting exogenous FBA, the exogenous stimulus-driven influence of FBA is elusive at best, and that FBA is primarily a top-down, goal-driven process.

Non-spatial context-driven search.

Contexts that predict characteristics of search targets can guide attention by triggering attentional control settings for the characteristics. However, this context-driven search has most commonly been found in the spatial dimension. The present study explored the context-driven search when shape contexts predict the color of targets: non-spatial context-driven search. It has been demonstrated that context-driven search requires cognitive resources, and evidence of non-spatial context-driven search is found when there is an increase in cognitive resources for the shape/color associations. Thus, the scarcity of evidence for non-spatial context-driven search is potentially because the context-driven search requires more cognitive resources for shape/color associations than for spatial/spatial associations. In the current study, we violated a previously 100% consistent shape/color association with two mismatch trials to encourage allocation of cognitive resources to the shape/color association. Three experiments showed that the shape-predicted color cues captured attention more than the non-predicted color cues, indicating that shape contexts triggered attentional control settings for a color predicted by the contexts. Furthermore, the shape contexts guided attention to the predicted color only after the two mismatch trials, suggesting that expression of the non-spatial context-driven search may require cognitive resources more than the spatial context-driven search.

Learned prioritization yields attentional biases through selection history.

While numerous studies have provided evidence for selection history as a robust influence on attentional allocation, it is unclear precisely which behavioral factors can result in this form of attentional bias. In the current study, we focus on "learned prioritization" as an underlying mechanism of selection history and its effects on selective attention. We conducted two experiments, each starting with a training phase to ensure that participants learned different stimulus priorities. This was accomplished via a visual search task in which a specific color was consistently more relevant when presented together with another given color. In Experiment 1, one color was always prioritized over another color and inferior to a third color, such that each color had an equal overall priority by the end of the training session. In Experiment 2, the three different colors had unequal priorities at the end of the training session. A subsequent testing phase in which participants had to search for a shape-defined target showed that only stimuli with unequal overall priorities (Experiment 2) affected attentional selection, with increased reaction times when a distractor was presented in a previously high-priority compared with a low-priority color. These results demonstrate that adopting an attentional set where certain stimuli are prioritized over others can result in a lingering attentional bias and further suggest that selection history does not equally operate on all previously selected stimuli. Finally, we propose that findings in value-driven attention studies where high-value and low-value signaling stimuli differentially capture attention may be a result of learned prioritization rather than reward.

Do we remember templates better so that we can reject distractors better?

Feature Integration Theory proposed that attention shifted between target-like representations in our visual field. However, the nature of the representations that determined what was target like received less specification than the nature of the attention shifts. In recent years, visual search research has focused on the nature of the memory representations that we use to guide our shifts of attention. Sensitive measures of memory quality indicate that the template representations are remembered better than other, merely maintained, memories. Here we tested the hypothesis that we prepare for difficult search tasks by storing a higher fidelity target representation in working memory than we do when preparing for an easy search task. To test this hypothesis, we explicitly tested participants' memory of the target color they searched for (i.e., the attentional template) versus another memory that was not used to guide attention (i.e., an accessory representation) following blocks of searches with easy-to-find targets (i.e., distractors were homogeneously colored) to blocks of searches with hard-to-find targets (i.e., distractors were heterogeneously colored). Although homogeneous-distractor searches required minimal precision for distractor rejection, we found that templates were still remembered better than accessories, just like we found in a heterogeneous-distractor search. As a consequence, we suggest that stronger memories for templates likely reflects the need to decide whether new perceptual inputs match the template, and not an attempt to create a better template representation in anticipation of difficult searches.

Creating a network of importance: The particular effects of self-relevance on stimulus processing.

Several factors guide our attention and the way we process our surroundings. In that regard, there is an ongoing debate about the way we are influenced by stimuli that have a particular self-relevance for us. Recent findings suggest that self-relevance does not always capture our attention automatically. Instead, an interpretation of the literature might be that self-relevance serves as an associative advantage facilitating the integration of relevant stimuli into the self-concept. We compared the effect of self-relevant stimuli with the effect of negative stimuli in three tasks measuring different aspects of cognitive processing. We found a first dissociation suggesting that negative valence attracts attention while self-relevance does not, a second dissociation suggesting that self-relevance influences stimulus processing beyond attention-grabbing mechanisms and in the form of an "associative glue," while negative valence does not, and, last but not least, a third dissociation suggesting that self-relevance influences stimulus processing at a later stage than negative valence does.

Altering the rhythm of target and background talkers differentially affects speech understanding.

Three experiments investigated listeners' ability to use speech rhythm to attend selectively to a single target talker presented in multi-talker babble (Experiments 1 and 2) and in speech-shaped noise (Experiment 3). Participants listened to spoken sentences of the form "Ready [Call sign] go to [Color] [Number] now" and reported the Color and Number spoken by a target talker (cued by the Call sign "Baron"). Experiment 1 altered the natural rhythm of the target talker and background talkers for two-talker and six-talker backgrounds. Experiment 2 considered parametric rhythm alterations over a wider range, altering the rhythm of either the target or the background talkers. Experiments 1 and 2 revealed that altering the rhythm of the target talker, while keeping the rhythm of the background intact, reduced listeners' ability to report the Color and Number spoken by the target talker. Conversely, altering the rhythm of the background talkers, while keeping the target rhythm intact, improved listeners ability to report the Color and Number spoken by the target talker. Experiment 3, which embedded the target talker in speech-shaped noise rather than multi-talker babble, similarly reduced recognition of the target sentence with increased alteration of the target rhythm. This pattern of results favors a dynamic-attending theory-based selective-entrainment hypothesis over a disparity-based segregation hypothesis and an increased salience hypothesis.