Detrimental Effects of Irrelevant Speech on Serial Recall of Visual Items are Reflected in Reduced Visual N1 and Reduced Theta Activity

Temporal features of size constancy for perception and action in a real-world setting: A combined EEG-kinematics study

A stable representation of object size, in spite of continuous variations in retinal input due to changes in viewing distance, is critical for perceiving and acting in a real 3D world. In fact, our perceptual and visuo-motor systems exhibit size and grip constancies in order to compensate for the natural shrinkage of the retinal image with increased distance. The neural basis of this size-distance scaling remains largely unknown, although multiple lines of evidence suggest that size-constancy operations might take place remarkably early, already at the level of the primary visual cortex. In this study, we examined for the first time the temporal dynamics of size constancy during perception and action by using a combined measurement of event-related potentials (ERPs) and kinematics. Participants were asked to maintain their gaze steadily on a fixation point and perform either a manual estimation or a grasping task towards disks of different sizes placed at different distances. Importantly, the physical size of the target was scaled with distance to yield a constant retinal angle. Meanwhile, we recorded EEG data from 64 scalp electrodes and hand movements with a motion capture system. We focused on the first positive-going visual evoked component peaking at approximately 90 ms after stimulus onset. We found earlier latencies and greater amplitudes in response to bigger than smaller disks of matched retinal size, regardless of the task. In line with the ERP results, manual estimates and peak grip apertures were larger for the bigger targets. We also found task-related differences at later stages of processing from a cluster of central electrodes, whereby the mean amplitude of the P2 component was greater for manual estimation than grasping. Taken together, these findings provide novel evidence that size constancy for real objects at real distances occurs at the earliest cortical stages and that early visual processing does not change as a function of task demands.

Negative target stimuli do not influence cross-modal auditory distraction

The present study served to test whether emotion modulates auditory distraction in a serial-order reconstruction task. If auditory distraction results from an attentional trade-off between the targets and distractors, auditory distraction should decrease when attention is focused on targets with high negative arousal. Two experiments (with a total N of 284 participants) were conducted to test whether auditory distraction is influenced by target emotion. In Experiment 1 it was examined whether two benchmark effects of auditory distraction-the auditory-deviant effect and the changing-state effect-differ as a function of whether negative high-arousal targets or neutral low-arousal targets are used. Experiment 2 complements Experiment 1 by testing whether target emotion modulates the disruptive effects of reversed sentential speech and steady-state distractor sequences relative to a quiet control condition. Even though the serial order of negative high-arousal targets was better remembered than that of neutral low-arousal targets, demonstrating an emotional facilitation effect on serial-order reconstruction, auditory distraction was not modulated by target emotion. The results provide support of the automatic-capture account according to which auditory distraction, regardless of the specific type of auditory distractor sequence that has to be ignored, is a fundamentally stimulus-driven effect that is rooted in the automatic processing of the to-be-ignored auditory stream and remains unaffected by emotional-motivational factors.

Functional impact of bothersome tinnitus on cognitive test performance

OBJECTIVE

Individuals with bothersome tinnitus frequently report their concentration is affected. Given that tinnitus is the leading service-connected disability compensated by the United States Department of Veterans Affairs, it is essential to determine whether tinnitus has a functional impact on the operational performance of Service members. Previous studies demonstrated that people with tinnitus perform more poorly on cognitive tests of selective attention and memory than those without tinnitus. This study aimed to compare performance between participants with and without tinnitus on visually based tests of selective attention (flanker task) and short-term memory (spatial letter location) that were self-administered under three auditory conditions (quiet, broadband noise and speech) using a tablet-based test protocol.

DESIGN

Experimental.

STUDY SAMPLE

Thirty participants with bothersome tinnitus and 30 control participants, matched for age and hearing loss.

RESULTS

The results revealed a significantly larger flanker effect and shorter memory span in the tinnitus group compared to the control group, consistent with previous studies. Performance accuracy was comparable between the groups.

CONCLUSIONS

The results suggest bothersome tinnitus may affect cognitive efficiency more than cognitive performance. The tablet-based protocol has the potential to be implemented clinically as a functional measure of the impact of bothersome tinnitus on concentration.

The vulnerability of working memory to distraction is rhythmic

Recent research posits that the cognitive system samples target stimuli in a rhythmic fashion, characterized by target detection fluctuating at frequencies of ~3-8 Hz. Besides prioritized encoding of targets, a key cognitive function is the protection of working memory from distractor intrusion. Here, we test to which degree the vulnerability of working memory to distraction is rhythmic. In an Irrelevant-Speech Task, N = 23 human participants had to retain the serial order of nine numbers in working memory while being distracted by task-irrelevant speech with variable temporal onsets. The magnitude of the distractor-evoked N1 component in the event-related potential as well as behavioural recall accuracy, both measures of memory distraction, were periodically modulated by distractor onset time in approximately 2-4 cycles per second (Hz). Critically, an underlying 2.5-Hz rhythm explained variation in both measures of distraction such that stronger phasic distractor encoding mediated lower phasic memory recall accuracy. In a behavioural follow-up experiment, we tested whether these results would replicate in a task design without rhythmic presentation of target items. Participants (N = 6 with on average >2500 trials, each) retained two line-figures in memory while being distracted by acoustic noise of varying onset across trials. In agreement with the main experiment, the temporal onset of the distractor periodically modulated memory performance. These results suggest that during working memory retention, the human cognitive system implements distractor suppression in a temporally dynamic fashion, reflected in ~400-ms long cycles of high versus low distractibility.

Contextual effects of angry vocal expressions on the encoding and recognition of emotional faces: An event-related potential (ERP) study

It has been shown that stimulus memory (e.g., encoding and recognition) is influenced by emotion. In terms of face memory, event-related potential (ERP) studies have shown that the encoding of emotional faces is influenced by the emotion of concomitant context, when contextual stimuli were input from a visual modality. Behavioral studies also investigated the effect of contextual emotion on subsequent recognition of neutral faces. However, there might be no studies ever investigating the context effect on face encoding and recognition, when contextual stimuli were input from other sensory modalities (e.g., an auditory modality). Additionally, it may be unknown about the neural mechanisms underlying context effects on recognition of emotional faces. Therefore, the present study aimed to use vocal expressions as contexts to investigate whether contextual emotion influences ERP responses during face encoding and recognition. To this end, participants in the present study were asked to memorize angry and neutral faces. The faces were presented concomitant with either angry or neutral vocal expressions. Subsequently, participants were asked to perform an old/new recognition task, in which only faces were presented. In the encoding phase, ERP results showed that compared to neutral vocal expression, angry vocal expressions led to smaller P1 and N170 responses to both angry and neutral faces. For angry faces, however, late positive potential (LPP) responses were increased in the angry voice condition. In the later recognition phase, N170 responses were larger for neutral-encoded faces that had been presented with angry compared to neutral vocal expressions. Preceding angry vocal expression increased FN400 and LPP responses to both neutral-encoded and angry-encoded faces, when the faces showed the encoded expression. Therefore, the present study indicates that contextual emotion with regard to vocal expression influences neural responses during face encoding and subsequent recognition.

The impact of road traffic noise on cognitive performance in attention-based tasks depends on noise level even within moderate-level ranges

Little empirical evidence is available regarding the effects of road traffic noise on cognitive performance in adults, although traffic noise can be heard at many offices and home office workplaces. Our study tested the impact of road traffic noise at different levels (50 dB(A), 60 dB(A), 70 dB(A)) on performance in three tasks that differed with respect to their dependency on attentional and storage functions, as follows: The Stroop task, in which performance relied predominantly on attentional functions (e.g., inhibition of automated responses; Experiment 1: n = 24); a non-automated multistage mental arithmetic task calling for both attentional and storage functions (Exp. 2: n = 18); and verbal serial recall, which placed a burden predominantly on storage functions (Experiment 3: n = 18). Better performance was observed during moderate road traffic noise at 50 dB(A) compared to loud traffic noise at 70 dB(A) in attention-based tasks (Experiments 1-2). This contrasted with the effects of irrelevant speech (60 dB(A)), which was included in the experiments as a well-explored and common noise source in office settings. A disturbance impact of background speech was only given in the two tasks that called for storage functions (Experiments 2-3). In addition to the performance data, subjective annoyance ratings were collected. Consistent with the level effect of road traffic noise found in the performance data, a moderate road traffic noise at 50 dB(A) was perceived as significantly less annoying than a loud road traffic noise at 70 dB(A), which was found, however, independently of the task at hand. Furthermore, the background sound condition with the highest detrimental performance effect in a task was also rated as most annoying in this task, i.e., traffic noise at 70 dB(A) in the Stroop task, and background speech in the mental arithmetic and serial recall tasks.

High working memory capacity does not always attenuate distraction: Bayesian evidence in support of the null hypothesis

Individual differences in working memory capacity (WMC) predict individual differences in basically all tasks that demand some form of cognitive labor, especially if the persons conducting the task are exposed to distraction. As such, tasks that measure WMC are very useful tools in individual-differences research. However, the predictive power of those tasks, combined with conventional statistical tools that cannot support the null hypothesis, also makes it difficult to study the limits of that power. In this article, we review studies that have failed to find a relationship between WMC and effects of auditory distraction on visual–verbal cognitive performance, and use meta-analytic Bayesian statistics to test the null hypothesis. The results favor the assumption that individual differences in WMC are, in fact, not (always) related to the magnitude of distraction. Implications for the nature of WMC are discussed.

Irrelevant speech disrupts item-context binding

The present study examines the effects of irrelevant speech on immediate memory. Previous research led to the suggestion that auditory distractors particularly impair memory for serial order. These findings were explained by assuming that irrelevant speech disrupts the formation and maintenance of links between adjacent items in a to-be-remembered sequence, resulting in a loss of order information. Here we propose a more general explanation of these findings by claiming that the capacity to form and maintain item-context bindings is generally impaired by the presence of auditory distractors. The results of Experiment 1 show that memory for the association between an item and its background color is drastically impaired by irrelevant speech, just as memory for the association between an item and its serial position. In Experiment 2 it was examined whether the disrupting effects of irrelevant sound are limited to memory for item-context associations or whether item memory is also affected by the auditory distractors. The results revealed that irrelevant speech disrupts both item memory and item-context binding. The results suggest that the effects of irrelevant sound on immediate memory are more general than previously assumed, which has important theoretical and applied implications.

Activations of human auditory cortex to phonemic and nonphonemic vowels during discrimination and memory tasks

We used fMRI to investigate activations within human auditory cortex (AC) to vowels during vowel discrimination, vowel (categorical n-back) memory, and visual tasks. Based on our previous studies, we hypothesized that the vowel discrimination task would be associated with increased activations in the anterior superior temporal gyrus (STG), while the vowel memory task would enhance activations in the posterior STG and inferior parietal lobule (IPL). In particular, we tested the hypothesis that activations in the IPL during vowel memory tasks are associated with categorical processing. Namely, activations due to categorical processing should be higher during tasks performed on nonphonemic (hard to categorize) than on phonemic (easy to categorize) vowels. As expected, we found distinct activation patterns during vowel discrimination and vowel memory tasks. Further, these task-dependent activations were different during tasks performed on phonemic or nonphonemic vowels. However, activations in the IPL associated with the vowel memory task were not stronger during nonphonemic than phonemic vowel blocks. Together these results demonstrate that activations in human AC to vowels depend on both the requirements of the behavioral task and the phonemic status of the vowels.

The impact of auditory distraction on retrieval of visual memories

Recent research has revealed that the presence of irrelevant visual information during retrieval of long-term memories diminishes recollection of task-relevant visual details. Here, we explored the impact of irrelevant auditory information on remembering task-relevant visual details by probing recall of the same previously viewed images while participants were in complete silence, exposed to white noise, or exposed to ambient sounds recorded at a busy café. The presence of auditory distraction diminished objective recollection of goal-relevant details, relative to the silence and white noise conditions. Critically, a comparison with results from a previous study using visual distractors showed equivalent effects for auditory and visual distraction. These findings suggest that disruption of recollection by external stimuli is a domain-general phenomenon produced by interference between resource-limited, top-down mechanisms that guide the selection of mnemonic details and control processes that mediate our interactions with external distractors.

Speech versus non-speech as irrelevant sound: controlling acoustic variation

Functional differences between speech and non-speech within the irrelevant sound effect were investigated using repeated and changing formats of irrelevant sounds in the form of intelligible words and unintelligible signal correlated noise (SCN) versions of the words. Event-related potentials were recorded from 25 females aged between 18 and 25 while they completed a serial order recall task in the presence of irrelevant sound or silence. As expected and in line with the changing-state hypothesis both words and SCN produced robust changing-state effects. However, words produced a greater changing-state effect than SCN indicating that the spectral detail inherent within speech accounts for the greater irrelevant sound effect and changing-state effect typically observed with speech. ERP data in the form of N1 amplitude was modulated within some irrelevant sound conditions suggesting that attentional aspects are involved in the elicitation of the irrelevant sound effect.

ERP correlates of the irrelevant sound effect

The irrelevant sound effect refers to a decrement in serial-recall performance when auditory distractors are played during encoding or retention of the to-be-remembered items. We examined the event-related brain potentials (ERPs) that were elicited in response to the auditory distractors during encoding and retention of visually presented target sequences. Changing-state distractor sequences that consisted of several different distractor items interfered more with serial recall than steady-state sequences that consisted of repetitions of a single distractor item. The ERP responses that were elicited in response to the distractors comprised the exogenous N1 component and were further characterized by a subsequent positive wave, and a late negativity. The changing-state effect was associated with an increased N1 and a P3a. The results support the attention-capture account of the irrelevant sound effect.