The negative affect hypothesis of noise sensitivity

Peer reviewe

Object-related brain potentials associated with the perceptual segregation of a dichotically embedded pitch

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Evaluating persistence of shape information using a matching protocol

Many laboratories have studied persistence of shape information, the goal being to better understand how the visual system mediates recognition of objects. Most have asked for recognition of known shapes, e.g., letters of the alphabet, or recall from an array. Recognition of known shapes requires access to long-term memory, so it is not possible to know whether the experiment is assessing short-term encoding and working memory mechanisms, or has encountered limitations on retrieval from memory stores. Here we have used an inventory of unknown shapes, wherein a string of discrete dots forms the boundary of each shape. Each was displayed as a target only once to a given respondent, with recognition being tested using a matching task. Analysis based on signal detection theory was used to provide an unbiased estimate of the probability of correct decisions about whether comparison shapes matched target shapes. Four experiments were conducted, which found the following: a) Shapes were identified with a high probability of being correct with dot densities ranging from 20% to 4%. Performance dropped only about 10% across this density range. b) Shape identification levels remained very high with up to 500 milliseconds of target and comparison shape separation. c) With one-at-a-time display of target dots, varying the total time for a given display, the proportion of correct decisions dropped only about 10% even with a total display time of 500 milliseconds. d) With display of two complementary target subsets, also varying the total time of each display, there was a dramatic decline of proportion correct that reached chance levels by 500 milliseconds. The greater rate of decline for the two-pulse condition may be due to a mechanism that registers when the number of dots is sufficient to create a shape summary. Once a summary is produced, the temporal window that allows shape information to be added may be more limited

Linear feedback decoupling—Transfer function analysis

Abstruct-The problem of linear system decoupling is examined based on recent results on linear feedback. New insight is obtained, through which resolution of the decoupling problem is accomplished by calculations, performed directly on the given transfer matrix. Computation of the decoupling compensators follows by easy constructions. The problem of feedback block decoupling with internal stability is also formulated and resolved

Processing of binaural spatial information in human auditory cortex : neuromagnetic responses to interaural timing and level differences

This study was designed to test two hypotheses about binaural hearing: (1) that binaural cues are primarily processed in the hemisphere contralateral to the perceived location of a sound; and (2) that the two main binaural cues, interaural timing differences and interaural level differences, are processed in separate channels in the auditory cortex. Magnetoencephalography was used to measure brain responses to dichotic pitches – a perception of pitch created by segregating a narrow band of noise from a wider band of noise – derived from interaural timing or level disparities. Our results show a strong modulation of interhemispheric M100 amplitudes by ITD cues. When these cues simulated source presentation unilaterally from the right hemispace, M100 amplitude changed from a predominant right hemisphere pattern to a bilateral pattern. In contrast, ILD cues lacked any capacity to alter the right hemispheric distribution. These data indicate that intrinsic hemispheric biases are large in comparison to any contralaterality biases in the auditory system. Importantly, both types of binaural cue elicited a circa 200 ms latency object-related negativity component, believed to reflect automatic cortical processes involved in distinguishing concurrent auditory objects. These results support the conclusion that ITDs and ILDs are processed by distinct neuronal populations to relatively late stages of cortical processing indexed by the M100. However information common to the two cues seems to be extracted for use in a subsequent stage of auditory scene segregation indexed by the object related negativity. This may place a new bound on the extent to which sound location cues are processed in separate channels of the auditory cortex.10 page(s

The Feasibility of Gelatin-Based Retronasal Stimuli to Assess Olfactory Perception

Links between some psychological disorders and olfactory deficits are well documented, and screening tests have been developed to exploit these associations. Odors can take one of two routes to the olfactory receptors in the nasal epithelium, the orthonasal or retronasal route. This article discusses the potential use of the retronasal route to assess olfaction using gelatin-based stimuli delivered orally. Using a relatively new psychophysical method, the Single-Interval Adjustment Matrix task, we estimated vanillin thresholds for five healthy participants sampling small vanillin flavored gels. Our data demonstrate the feasibility of using solid-state gustatory stimuli to assess retronasal perception

The late negativity for binaural pitches: Object related negativity or pitch onset response?

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Neural activity associated with binaural processes for the perceptual segregation of pitch

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Event-related potentials for interaural time differences and spectral cues

Dichotic pitches and mistuned harmonics can each lead to the perception of one or two auditory objects. Comparison of event-related potentials for the perception of one versus two objects reveals an early negative and a late positive component. The relationship of these components with auditory segregation was further investigated using stimuli containing monaural spectral cues to pitch, binaural timing cues to pitch, or a combination of both, interleaved with control stimuli (no pitch). Stimuli containing timing cues or a combination of timing and spectral cues reliably elicited both components, which were of larger amplitude when both cues were present. For stimuli containing only spectral cues, the early component was attenuated in amplitude and no measurable late component was detected