Temporal integration in auditory signal detection

Cognitive mechanisms hypothesized to underlie hallucinatory experiences (HEs) include dysfunctional source monitoring, heightened signal detection, or impaired attentional processes. HEs can be very pronounced in psychosis, but similar experiences also occur in nonclinical populations. Using data from an international multisite study on nonclinical subjects (N = 419), we described the overlap between two sets of variables - one measuring cognition and the other HEs - at the level of individual items, allowing extraction of item-specific signal which might considered off-limits when summary scores are analyzed. This involved using a statistical hypothesis test at the multivariate level, and variance constraints, dimension reduction, and split-half reliability checks at the level of individual items. The results showed that (1) modality-general HEs involving sensory distortions (hearing voices/sounds, troubled by voices, everyday things look abnormal, sensations of presence/movement) were associated with more liberal auditory signal detection, and (2) HEs involving experiences of sensory overload and vivid images/imagery (viz., HEs for faces and intense daydreams) were associated with other-ear distraction and reduced laterality in dichotic listening. Based on these results, it is concluded that the overlap between HEs and cognition variables can be conceptualized as modality-general and bi-dimensional: one involving distortions, and the other involving overload or intensity.

Download Full-text

Assessing audiovisual saliency and visual-information content in the articulation of consonants and vowels on audiovisual temporal perception

Seeing and Perceiving ◽

10.1163/187847612x646514 ◽

2012 ◽

Vol 25 (0) ◽

pp. 29

Author(s):

Argiro Vatakis ◽

Charles Spence

Keyword(s):

Visual Information ◽

Temporal Order ◽

Temporal Integration ◽

Visual Speech ◽

Auditory Signal ◽

Audiovisual Speech Perception ◽

Speech Stream ◽

Point Of Subjective Simultaneity ◽

Speech Token ◽

Manner Of Articulation

Research has revealed different temporal integration windows between and within different speech-tokens. The limited speech-tokens tested to date has not allowed for the proper evaluation of whether such differences are task or stimulus driven? We conducted a series of experiments to investigate how the physical differences associated with speech articulation affect the temporal aspects of audiovisual speech perception. Videos of consonants and vowels uttered by three speakers were presented. Participants made temporal order judgments (TOJs) regarding which speech-stream had been presented first. The sensitivity of participants’ TOJs and the point of subjective simultaneity (PSS) were analyzed as a function of the place, manner of articulation, and voicing for consonants, and the height/backness of the tongue and lip-roundedness for vowels. The results demonstrated that for the case of place of articulation/roundedness, participants were more sensitive to the temporal order of highly-salient speech-signals with smaller visual-leads at the PSS. This was not the case when the manner of articulation/height was evaluated. These findings suggest that the visual-speech signal provides substantial cues to the auditory-signal that modulate the relative processing times required for the perception of the speech-stream. A subsequent experiment explored how the presentation of different sources of visual-information modulated such findings. Videos of three consonants were presented under natural and point-light (PL) viewing conditions revealing parts, or the whole, face. Preliminary analysis revealed no differences in TOJ accuracy under different viewing conditions. However, the PSS data revealed significant differences in viewing conditions depending on the speech token uttered (e.g., larger visual-leads for PL-lip/teeth/tongue-only views).

Download Full-text

Externalizing biases and hallucinations in source-monitoring, self-monitoring and signal detection studies: a meta-analytic review

Psychological Medicine ◽

10.1017/s0033291712002760 ◽

2013 ◽

Vol 43 (12) ◽

pp. 2465-2475 ◽

Cited By ~ 87

Author(s):

M. L. Brookwell ◽

R. P. Bentall ◽

F. Varese

Keyword(s):

Signal Detection ◽

Source Monitoring ◽

Meta Analysis ◽

Experimental Studies ◽

Correlation Study ◽

Auditory Signal ◽

Self Monitoring ◽

Analytic Review ◽

External Sources ◽

Contacting Authors

BackgroundCognitive models have postulated that auditory hallucinations arise from the misattribution of internally generated cognitive events to external sources. Several experimental paradigms have been developed to assess this externalizing bias in clinical and non-clinical hallucination-prone samples, including source-monitoring, verbal self-monitoring and auditory signal detection tasks. This meta-analysis aims to synthesize the wealth of empirical findings from these experimental studies.MethodA database search was carried out for reports between January 1985 and March 2012. Additional studies were retrieved by contacting authors and screening references of eligible reports. Studies were considered eligible if they compared either (i) hallucinating and non-hallucinating patients with comparable diagnoses, or (ii) non-clinical hallucination-prone and non-prone participants using source-monitoring, verbal self-monitoring or signal detection tasks, or used correlational analyses to estimate comparable effects.ResultsThe analysis included 15 clinical (240 hallucinating patients and 249 non-hallucinating patients) and nine non-clinical studies (171 hallucination-prone and 177 non-prone participants; 57 participants in a correlation study). Moderate-to-large summary effects were observed in both the clinical and analogue samples. Robust and significant effects were observed in source-monitoring and signal detection studies, but not in self-monitoring studies, possibly due to the small numbers of eligible studies in this subgroup. The use of emotionally valenced stimuli led to effects of similar magnitude to the use of neutral stimuli.ConclusionsThe findings suggest that externalizing biases are important cognitive underpinnings of hallucinatory experiences. Clinical interventions targeting these biases should be explored as possible treatments for clients with distressing voices.

Download Full-text