Why are Background Telephone Conversations Distracting?

Telephone conversation is ubiquitous within the office setting. Overhearing a telephone conversation—whereby only one of the two speakers is heard—is subjectively more annoying and objectively more distracting than overhearing a full conversation. The present study sought to determine whether this "halfalogue" effect is attributable to unexpected offsets and onsets within the background speech (acoustic unexpectedness) or to the tendency to predict the unheard part of the conversation (semantic [un]predictability), and whether these effects can be shielded against through top-down cognitive control. In Experiment 1, participants performed an office-related task in quiet or in the presence of halfalogue and dialogue background speech. Irrelevant speech was either meaningful or meaningless speech. The halfalogue effect was only present for the meaningful speech condition. Experiment 2 addressed whether higher task-engagement could shield against the halfalogue effect by manipulating the font of the to-be-read material. While the halfalogue effect was found with an easy-to-read font (fluent text), the use of a difficult-to-read font (disfluent text) eliminated the effect. The halfalogue effect is thus attributable to the semantic (un)predictability, not the acoustic unexpectedness, of background telephone conversation and can be prevented by simple means such as increasing the level of engagement required by the focal task

Hyper-arousal decreases human visual thresholds

Arousal has long been known to influence behavior and serves as an underlying component of cognition and consciousness. However, the consequences of hyper-arousal for visual perception remain unclear. The present study evaluates the impact of hyper-arousal on two aspects of visual sensitivity: visual stereoacuity and contrast thresholds. Sixty-eight participants participated in two experiments. Thirty-four participants were randomly divided into two groups in each experiment: Arousal Stimulation or Sham Control. The Arousal Stimulation group underwent a 50-second cold pressor stimulation (immersing the foot in 0–2° C water), a technique known to increase arousal. In contrast, the Sham Control group immersed their foot in room temperature water. Stereoacuity thresholds (Experiment 1) and contrast thresholds (Experiment 2) were measured before and after stimulation. The Arousal Stimulation groups demonstrated significantly lower stereoacuity and contrast thresholds following cold pressor stimulation, whereas the Sham Control groups showed no difference in thresholds. These results provide the first evidence that hyper-arousal from sensory stimulation can lower visual thresholds. Hyper-arousal\u27s ability to decrease visual thresholds has important implications for survival, sports, and everyday life

Sensorimotor Modulations by Cognitive Processes During Accurate Speech Discrimination: An EEG Investigation of Dorsal Stream Processing

Internal models mediate the transmission of information between anterior and posterior regions of the dorsal stream in support of speech perception, though it remains unclear how this mechanism responds to cognitive processes in service of task demands. The purpose of the current study was to identify the influences of attention and working memory on sensorimotor activity across the dorsal stream during speech discrimination, with set size and signal clarity employed to modulate stimulus predictability and the time course of increased task demands, respectively. Independent Component Analysis of 64–channel EEG data identified bilateral sensorimotor mu and auditory alpha components from a cohort of 42 participants, indexing activity from anterior (mu) and posterior (auditory) aspects of the dorsal stream. Time frequency (ERSP) analysis evaluated task-related changes in focal activation patterns with phase coherence measures employed to track patterns of information flow across the dorsal stream. ERSP decomposition of mu clusters revealed event-related desynchronization (ERD) in beta and alpha bands, which were interpreted as evidence of forward (beta) and inverse (alpha) internal modeling across the time course of perception events. Stronger pre-stimulus mu alpha ERD in small set discrimination tasks was interpreted as more efficient attentional allocation due to the reduced sensory search space enabled by predictable stimuli. Mu-alpha and mu-beta ERD in peri- and post-stimulus periods were interpreted within the framework of Analysis by Synthesis as evidence of working memory activity for stimulus processing and maintenance, with weaker activity in degraded conditions suggesting that covert rehearsal mechanisms are sensitive to the quality of the stimulus being retained in working memory. Similar ERSP patterns across conditions despite the differences in stimulus predictability and clarity, suggest that subjects may have adapted to tasks. In light of this, future studies of sensorimotor processing should consider the ecological validity of the tasks employed, as well as the larger cognitive environment in which tasks are performed. The absence of interpretable patterns of mu-auditory coherence modulation across the time course of speech discrimination highlights the need for more sensitive analyses to probe dorsal stream connectivity

Biopsychosocial Predictors of Paranoia in the Attenuated Psychosis Syndrome

Despite a consensus that psychosocial adversity plays a role in the onset of psychosis, the nature of this role and the underlying neurobiological mechanisms remain unclear. This study examined the complex relationship between perceived ethnic discrimination (PED) and paranoid ideation and its mediating factors, in individuals with Attenuated Psychotic Syndrome (APS) using a virtual reality paradigm to objectively quantify paranoia. Secondly, a sensory gating deficit, indexed by P50 Event Related Potential (ERP) abnormalities was examined, and the combined effect of electrophysiological sensory gating deficits and psycho-social adversity on the development of psychosis was explored. Results showed that perceived maternal neglect and antipathy in childhood, PED and perceived social support were key factors in young adults with APS. Also PED was positively correlated with persecutory paranoia. Furthermore, individuals with APS displayed sensory gating impairments. Therefore, perceived exposure to adverse experiences and sensory gating deficits observed in individuals with APS are present before the first episode and are consistent with current biopsychosocial models in which early psychosocial stress, later psychosocial adversity and neurocognitive functioning plays a key role in the development of psychosis

INFLUENCES OF SENSORY MODALITY AND STIMULUS TYPE ON PROCESSING TASK-IRRELEVANT STIMULI

Ph.D

The Spectrotemporal Filter Mechanism of Auditory Selective Attention

SummaryAlthough we have convincing evidence that attention to auditory stimuli modulates neuronal responses at or before the level of primary auditory cortex (A1), the underlying physiological mechanisms are unknown. We found that attending to rhythmic auditory streams resulted in the entrainment of ongoing oscillatory activity reflecting rhythmic excitability fluctuations in A1. Strikingly, although the rhythm of the entrained oscillations in A1 neuronal ensembles reflected the temporal structure of the attended stream, the phase depended on the attended frequency content. Counter-phase entrainment across differently tuned A1 regions resulted in both the amplification and sharpening of responses at attended time points, in essence acting as a spectrotemporal filter mechanism. Our data suggest that selective attention generates a dynamically evolving model of attended auditory stimulus streams in the form of modulatory subthreshold oscillations across tonotopically organized neuronal ensembles in A1 that enhances the representation of attended stimuli

The directional effect of target position on spatial selective auditory attention

Spatial selective auditory attention plays a crucial role in listening in a mixture of competing speech sounds. Previous neuroimaging studies have reported alpha band neural activity modulated by auditory attention, along with the alpha lateralization corresponding to attentional focus. A greater cortical representation of the attended speech envelope compared to the ignored speech envelope was also found, a phenomenon known as \u27neural speech tracking’. However, little is known about the neural activities when attentional focus is directed on speech sounds from behind the listener, even though understanding speech from behind is a common and essential aspect of daily life. The objectives of this study are to investigate the impact of four distinct target positions (left, right, front, and particularly, behind) on spatial selective auditory attention by concurrently assessing 1) spatial selective speech identification, 2) oscillatory alpha-band power, and 3) neural speech tracking. Fifteen young adults with normal hearing (NH) were enrolled in this study (M = 21.40, ages 18-29; 10 females). The selective speech identification task indicated that the target position presented at back was the most challenging condition, followed by the front condition, with the lateral condition being the least demanding. The normalized alpha power was modulated by target position and the power was significantly lateralized to either the left or right side, not the front and back. The parieto-occipital alpha power in front-back configuration was significantly lower than the results for left-right listening configuration and the normalized alpha power in the back condition was significantly higher than in the front condition. The speech tracking function of to-be-attended speech envelope was affected by the direction of ix target stream. The behavioral outcome (selective speech identification) was correlated with parieto-occipital alpha power and neural speech tracking correlation coefficient as neural correlates of auditory attention, but there was no significant correlation between alpha power and neural speech tracking. The results suggest that in addition to existing mechanism theories, it might be necessary to consider how our brain responds depending on the location of the sound in order to interpret the neural correlates and behavioral consequences in a meaningful way as well as a potential application of neural speech tracking in studies on spatial selective hearing

Multimodal attention in a simulated driving environment - Novel approaches to the quantification of attention based on brain activity

The concept of attention is an established focus of study in neurosciences. The quantification of attention during driving can help identify situations in which the driver is not completely aware of the situation. This work deals with the implementation of a setup to simulate a driving environment that enables audiovisual tasks to be embedded into the driving task while acquiring biosignals such as electroencephalography. The main goal of this dissertation was to find a correlation between attention and brain activity as seen on the electroencephalographic activity while driving. By using the principle of phase-amplitude coupling in electroencephalographic signals, it was hypothesized that Theta-Gamma phase-amplitude coupling might correlate to multimodal attention and thus might be eligible as a biomarker of attention in tasks such as driving. Surface electroencephalography was measured simultaneously in drivers and copilots while participating in simulated driving scenarios with varying multimodal attentional demands. The phase-amplitude coupling between Theta-band phase and Gamma-band amplitude from the electroencephalograpic signal was obtained and evaluated. Results showed significant phase-amplitude coupling differences between drivers and copilots in areas related to multimodal attention (prefrontal cortex, frontal eye fields, primary motor cortex, and visual cortex). The results were confirmed by behavioral data acquired during the test (detection task). We conclude that phase-amplitude coupling does function as a biomarker for attentional demand by detecting cortical areas being activated through specific multimodal (in this case, driving) tasks. Additionally, the data acquired in the main work of this thesis was used to test an auditory stimulus reconstruction algorithm previously tested by our work group. The stimulus reconstruction allowed to obtain post-hoc additional information regarding attentional effort during driving (success of the stimulus reconstruction was significantly correlated to auditory effort) and serves as a compliment to the main results. This dissertation thus offers an insight on attentional systems in multimodal situations and the neurophysiological systems underlying attention. It develops methods to measure attention in a driving environment, both as seen using phase-amplitude coupling and by being able to single out auditory effort by reconstructing the auditory stimuli. Finally, these methods can be translated to other activities since they are both based on non-invasive electroencephalography