Perceptual Anomalies Research Articles

Evidence for Specific Associations Between Depressive Symptoms, Psychotic Experiences, and Suicidal Ideation in Chilean Adolescents From the General Population

Associations between psychotic experiences and suicidal ideation are not yet fully understood, and the potential role of depressive symptoms in this relationship remains unclear. The current study examined relationships between depressive symptoms (DS), psychotic experiences (PE) and suicidal ideation (SI) using two complementary approaches on cross-sectional data from a community sample of adolescents aged 13–19 years (N = 1,591). First, we investigated the association between the three domains using mediation analysis, showing that depressive symptoms partly mediate the relationship between psychotic experiences and suicidal ideation. Second, we looked at associations between the three domains at item level using network analysis. Specific associations between symptoms of the three domains were found, indicating depressive symptoms of sadness, avolition, pessimism, and self-criticalness/worthlessness as the most central symptoms in the network. Suicidal ideation was associated with the depressive symptoms pessimism and worthlessness, to social anxiety, and to perceptual anomalies. Our results show that the mediating effect of depressive symptoms between psychotic experiences and suicidal ideation may be due to associations between specific aspects of SI, depressive symptoms and psychotic experiences. These findings can contribute to the planning of health services and programs aimed at the timely detection of psychopathology and suicidal risk in young people.

Individual differences in the tendency to see the expected.

Prior knowledge has been shown to facilitate the incorporation of visual stimuli into awareness. We adopted an individual differences approach to explore whether a tendency to 'see the expected' is general or method-specific. We administered a binocular rivalry task and manipulated selective attention, as well as induced expectations via predictive context, self-generated imagery, expectancy cues, and perceptual priming. Most prior manipulations led to a facilitated awareness of the biased percept in binocular rivalry, whereas strong signal primes led to a suppressed awareness, i.e., adaptation. Correlations and factor analysis revealed that the facilitatory effect of priors on visual awareness is closely related to attentional control. We also investigated whether expectation-based biases predict perceptual abilities. Adaptation to strong primes predicted improved naturalistic change detection and the facilitatory effect of weak primes predicted the experience of perceptual anomalies. Taken together, our results indicate that the facilitatory effect of priors may be underpinned by an attentional mechanism but the tendency to 'see the expected' is method-specific.

Don't worry, be happy: Protective factors to buffer against distress associated with psychotic experiences

BackgroundAround 6–7% of the general population report psychotic experiences (PEs). Positive PEs (e.g. hearing voices) may increase the risk of development of psychotic disorder. An important predictor of the transition to a psychotic disorder is secondary distress associated with PEs. We examined the moderating effect of potential protective factors on this secondary distress. MethodsData come from 2870 individuals of the HowNutsAreTheDutch study. PEs were assessed with the Community Assessment of Psychic Experience (CAPE) questionnaire and were divided into three subdomains (“Bizarre experiences”, “Delusional ideations”, and “Perceptual anomalies”). Protective factors explored were having a partner, having a pet, benevolent types of humor, optimism and the high levels of personality traits emotional stability (reversed neuroticism), extraversion, openness to experience, conscientiousness, and agreeableness. We examined whether these protective factors moderated (lowered) the association between frequency of PEs and PE-associated distress.Results: Due to low prevalence of perceptual anomalies in the sample, this domain was excluded from analysis. No moderating effects were observed of protective factors on the association between bizarre experiences and distress. Having a partner and high levels of optimism, self-enhancing humor, openness, extraversion and emotional stability moderated the association between delusional ideations and secondary distress, leading to lower levels of distress. ConclusionsSeveral protective factors were found to moderate the association between frequency and secondary distress of delusional ideations, with high levels of the protective factors being associated with lower levels of distress. A focus on protective factors could be relevant for interventions and prevention strategies regarding psychotic phenomena.

O3.3. DO DEPRESSIVE SYMPTOMS MEDIATE THE RELATIONSHIPS BETWEEN SUICIDAL IDEATION AND PSYCHOTIC EXPERIENCES IN ADOLESCENTS?

BackgroundYouth mental health is a global challenge, with onset of mental illness peaking in adolescence. In this population, depressive symptoms (DS), psychotic experiences (PE) and suicidal ideation (SI) are prevalent and risk factors for future mental disorders. DS could mediate relationships between psychotic experiences (PE) and suicidal ideation (SI); however, its precise role in this association remains uncertain. We examined whether depressive symptoms mediate the association between psychotic experiences and suicidal ideation using two complementary approaches to cross-sectional data from a community sample of adolescents. We hypothesized that DS mediate relationships between PE and SI. Additionally, we expected to find that specific DS would play a central role in this association and that this would show via higher centrality values for affective symptoms reflecting low energy, hopelessness and self-depreciating feelings in the network analyses.MethodsWe examined cross-sectional relationships between PE, SI and DS in a community sample of adolescents (N= 1715; 13–19 years old) recruited from Chilean secondary schools between April and August 2015. We addressed depressive symptoms (DS) using the Depression and Anxiety Scale (DASS-21). We assessed suicidal ideation using 6 items of the Columbia Suicide Severity Rating Scale (C-SSRS), adapted for being used as a self-report questionnaire. We addressed psychotic experiences (PE) by items of two pre-existing scales we adapted in prior studies with adolescents: the Community Assessment of Psychic Experiences - Positive scale (CAPE-P15), and the Brief Self-report Questionnaire for Screening Putative Pre-psychotic States (BQSPS). We first conducted a mediation analysis, where PE was the predictor, SI was the outcome, and DS were the mediator variables. Next, we performed a network analysis and estimated the strength centrality index for each symptom, and the network robustness through accuracy and stability test.ResultsPearson’s correlations showed significant associations between all the variables in (SI-DS: r= .491, p<.001; PE-SI: r= .436, p<.001; PE-DS: r= .617, p<.001). No demographic variables (i.e gender, age) had to be controlled for in the mediation.The mediation analysis yielded that depression mediates the relationship between PE and SI (b= .2206, 95% BCa CI [.1783, .2644]). Additionally, network analysis showed the following strength centrality values (SV): depression (mean= 5.92, σ2=1.72; median= 6.08); bizarre experiences (mean= 3.94, σ2=0.35; median= 4.02); perceptual anomalies (mean= 3.75, σ2=2.21; median= 3.75); social anxiety (mean= 3.49, σ2=0.79; median= 3.23); negative symptoms (mean= 3.32, σ2=.23; median= 3.49). SI was strongly connected to pessimism (SV= .69); social anxiety (SV= .41); and self-criticalness/worthlessness (SV= .39). The correlation stability coefficient for the strength was (cor = 0.7) = 0.672, suggesting robustness of the findings.DiscussionOur findings support prior research showing that DS mediate relationship between PE and SI and adds to this literature by showing which symptoms in particular are important. Some specific depressive symptoms having a central role in this process (pessimism and worthlessness) and also psychotic experiences (social anxiety: being distant to people) and perceptual anomalies (seeing things other cannot) are connected in a meaningful way to suicidal ideation in a community sample of adolescents. These findings should be considered when planning early detection/intervention programs.

Psychotic Experiences in Schizophrenia and Sensitivity to Sensory Evidence.

Perceptual inference depends on an optimal integration of current sensory evidence with prior beliefs about the environment. Alterations of this process have been related to the emergence of positive symptoms in schizophrenia. However, it has remained unclear whether delusions and hallucinations arise from an increased or decreased weighting of prior beliefs relative to sensory evidence. To investigate the relation of this prior-to-likelihood ratio to positive symptoms in schizophrenia, we devised a novel experimental paradigm which gradually manipulates perceptually ambiguous visual stimuli by disambiguating stimulus information. As a proxy for likelihood precision, we assessed the sensitivity of individual participants to sensory evidence. As a surrogate for the precision of prior beliefs in perceptual stability, we measured phase duration in ambiguity. Relative to healthy controls, patients with schizophrenia showed a stronger increment in congruent perceptual states for increasing levels of disambiguating stimulus evidence. Sensitivity to sensory evidence correlated positively with the individual patients' severity of perceptual anomalies and hallucinations. Moreover, the severity of such experiences correlated negatively with phase duration. Our results indicate that perceptual anomalies and hallucinations are associated with a shift of perceptual inference toward sensory evidence and away from prior beliefs. This reduced prior-to-likelihood ratio in sensory processing may contribute to the phenomenon of aberrant salience, which has been suggested to give rise to the false inferences underlying psychotic experiences.

Altered neural oscillations and connectivity in the beta band underlie detail-oriented visual processing in autism

Sensory and perceptual anomalies may have a major impact on basic cognitive and social skills in humans. Autism Spectrum Disorder (ASD) represents a special perspective to explore this relationship, being characterized by both these features. The present study employed electroencephalography (EEG) to test whether detail-oriented visual perception, a recognized hallmark of ASD, is associated with altered neural oscillations and functional connectivity in the beta frequency band, considering its role in feedback and top-down reentrant signalling in the typical population. Using a visual crowding task, where participants had to discriminate a peripheral target letter surrounded by flankers at different distances, we found that detail-oriented processing in children with ASD, as compared to typically developing peers, could be attributed to anomalous oscillatory activity in the beta band (15–30 Hz), while no differences emerged in the alpha band (8–12 Hz). Altered beta oscillatory response reflected in turn atypical functional connectivity between occipital areas, where the initial stimulus analysis is accomplished, and infero-temporal regions, where objects identity is extracted. Such atypical beta connectivity predicted both ASD symptomatology and their detail-oriented processing. Overall, these results might be explained by an altered feedback connectivity within the visual system, with potential cascade effects in visual scene parsing and higher order functions.

Delusion formation as an inevitable consequence of a radical alteration in lived experience

ABSTRACT The definition of delusion is usually couched in terms of false beliefs held with conviction despite evidence to the contrary. Such beliefs are usually seen as impossible or implausible by others. In order to be classed as clinically significant, a delusion would lead a person to be distressed or to have significant problems with functioning. We note that a person ordinarily understands and negotiates the world based on familiar patterns derived from her cultural and historical experience. Thus, when her lived experience is altered, these assumptions about how the world works may be called in to question. Drawing on interviews conducted with people experiencing clinically significant delusions, we show how this alteration in lived experience manifests as emotional, affective and/or perceptual anomalies. We adopt the framework of the Enactive Approach which posits that a person interacts with her environment in terms of sense-making and we argue that radical alterations in lived experience can demand a renegotiating of how a person makes sense of this new world. We suggest that if the alteration in lived experience is sufficiently radical, then delusion formation is inevitable.

A simple method of quantifying chemotherapy-induced peripheral neuropathy using PainVision PS-2100®.

This study aimed to validate a simplified method of quantifying chemotherapy-induced peripheral neuropathy using the PainVision PS-2100® (PV) electrical perception system. We assessed patients diagnosed with epithelial ovarian cancer, fallopian tube cancer, or peritoneal cancer and were about to undergo first-time paclitaxel and carboplatin chemotherapy. Peripheral neuropathy was assessed before and after chemotherapy administration in all patients according to the National Cancer Institute-Common Terminology Criteria for Adverse Events Version 4.0 (NCI-CTCAE4.0), using a conventional assessment in combination with the PV system. The PV device comprises electrodes attached to the ulnar side of the forearm and the first joint of index fingers on both the left and right sides to measure the electrical perceptual threshold. The average of three threshold measurements was recorded for each patient. Thirty female patients (age 51.6 ± 12.2 [mean ± SD]) were included, and median number of chemotherapy drug treatments was 5 (first quartile: 4, second quartile: 5, and third quartile: 5). Twenty-seven patients (90%) reported posttreatment numbness; NCI-CTCAE4.0 perceptual anomaly grades were as follows: G1, 57 (40%); G2, 19 (13%); and G3, 7 (5%). A positive correlation was identified between right medial side PV threshold score and perceptual anomaly grade on measurements of the inner right-hand side only. Our preliminary results suggest that peripheral neuropathy may be quantified using PV. As CIPN often lowers QOL, it needs to be appropriately evaluated. Future studies with a larger patient cohort and methodological refinements to improve accuracy are warranted.

Strength of socio-political attitudes moderates electrophysiological responses to perceptual anomalies.

People with strong (vs. moderate) political attitudes have been shown to exhibit less phasic reactivity to perceptual anomalies, presumably to prevent their committed meaning systems from being challenged by novel experiences. Several researchers have proposed that (but not tested whether) firmly committed individuals also engage in more attentional suppression of anomalies, likely mediated by prestimulus alpha power. We expected participants with strong (vs. moderate) political attitudes to display increased pre-stimulus alpha power when processing perceptual anomalies. We recorded electrophysiological activity during the presentation of normal cards (control group) or both normal and anomalous playing cards (experimental group; total N = 191). In line with our predictions, the presence of anomalous playing cards in the stimulus set increased prestimulus alpha power only among individuals with strong but not moderate political attitudes. As potential markers of phasic reactivity, we also analyzed the late positive potential (LPP) and earlier components of the event-related potential, namely P1, N1, and P300. The moderating effect of extreme attitudes on ERP amplitudes remained inconclusive. Altogether, our findings support the idea that ideological conviction is related to increased tonic responses to perceptual anomalies.

Reduction in lower-alpha power during Ganzfeld flicker stimulation is associated with the production of imagery and trait positive schizotypy

Light-flicker Ganzfeld (LFG) induces a lower to upper-alpha frequency shift. However, it is unclear how this neurophysiological response might relate to LFG-induced pseudo-hallucinatory phenomena. It is also unknown whether emotional states (e.g., fear) or traits associated with risk for psychosis (e.g., proneness to perceptual anomalies, ability to produce vivid mental imagery) affect such neurophysiological and/or perceptual responses to LFG. The present study investigated alpha sub-bands during LFG across several flicker frequencies, in relation to individual differences in propensity for Ganzfeld-induced imagery (GI), positive schizotypy and trait mental imagery, and in relation to manipulations of affective state. Given previously reported sex differences in risk for psychosis and response to Ganzfeld, the effect of sex on GI was also studied. Forty-six healthy adults (16 men) completed psychometric measures of trait mental imagery and positive schizotypy before undergoing three LFG (20 min each) conditions. In each condition, participants wore white-out goggles and listened to either mood-inducing soundscapes (fear, serenity) or pink noise (control) through headphones. Greatest propensity for GI arose between 13.1 and 16.0 Hz flicker, with a peak at 16.0 Hz flicker. Occipital lower-alpha was reduced for lower flicker frequencies (13.1–16.0 Hz) and was inversely associated with GI. Upper-alpha power was not significantly related to GI or to other measures. Fear-induction was associated with reduction in alpha power, but did not significantly affect GI. Men reported more GI than women. Findings support a role for cortical destabilisation, as reflected in reduced lower-alpha, in perceptual anomalies; and, by extension, LFG as an experimental model of liability for psychosis.

Examining relationships between psychotic experiences and suicidal ideation in adolescents using a network approach

BackgroundSuicide is one of the leading causes of death in young individuals. Timely and adequate identification of individuals with suicidal ideation could prevent from suicidal behavior. Psychotic experiences (PE) have been shown to increase levels of suicidal ideation (SI) in the general population. Therefore, detailed investigation of the relationship of PE and SI is relevant. However, the exact nature of the relationship between these two phenomena remains unclear. Understanding psychopathology as a complex network of interacting symptoms could be helpful to elucidate specific associations existing between PE and SI. MethodA specific type of network analysis, the Ising model, was used to examine connections between dichotomized questions on psychotic experiences and suicidal ideation in a cross-sectional study with 1685 adolescents from the general population aged 13–18 years. ResultsSI was mostly connected to the PE domains perceptual anomalies (PA) and bizarre experiences (BE), which have higher strength values in the network. Central nodes within these domains, as indexed by higher centrality measures (strength and betweenness) were: auditory experiences (PA1: hearing voices when you are alone), persecutory ideation (BE1: feelings of being persecuted; BE2: conspiracy against you), and social anxiety (SANX) (SANX1: I cannot get close to people). ConclusionsSuicidal ideation is differentially connected to specific psychotic experiences. Auditory PE, persecutory ideation, and social anxiety symptoms could play a central role in the interconnectedness of the two constructs.

O8.1. EXAMINING RELATIONSHIPS BETWEEN PSYCHOTIC EXPERIENCES AND SUICIDAL IDEATION IN ADOLESCENTS USING A NETWORK APPROACH

BackgroundSuicide is the second cause one of the leading causes of death in young individuals. Timely and adequate identification of individuals with suicidal ideation could prevent from suicidal behavior. Psychotic experiences (PE) have been shown to increase levels of suicidal ideation (SI) in the general population. Therefore, detailed investigation of the relationship of PE and SI is relevant. However, the exact nature of the relationship between these two phenomena remains unclear, which is intensely debated nowadays. Given both the high complexity of SI and behavior and the fact that its expression has a trans-diagnostic nature, a fruitful approach to gain new insights about its relationships with psychiatric symptoms might be the application of network analysis, which could be helpful to elucidate specific associations existing between PE and SI.MethodsA specific type of network analysis, the Ising model, was used to examine connections between dichotomized questions on psychotic experiences and suicidal ideation in a cross-sectional study with 1685 adolescents from the general population aged 13–18 years. To assess psychotic experiences, we used an item generation deductive method (Hinkin, 1995) of two pre-existing scales that we adapted in previous studies: the Brief Self-report Questionnaire for Screening Putative Pre-psychotic States (BQSPS; Liu et al., 2013), and the Community Assessment of Psychic Experiences—Positive scale (CAPE-P15; Capra et al., 2013). The questionnaire encompassed 15 items addressing the following dimensions: perceptual anomalies (PA; 3 items); bizarre experiences (BE; 6 items); social anxiety (SA; 3 items); and negative symptoms (NS; 3 items). Suicidal ideation (SI) was assessed by six items of the Columbia–Suicide Severity Rating Scale (C-SSRS; Posner et al., 2011), adapted for being used as a self-report questionnaire. Severity of SI was rated on a 6-point ordinal scale in which 1 = wish to be dead, 2 = nonspecific active suicidal thoughts, 3 = thoughts about how to commit suicide, 4 = suicidal thoughts and intentions, 5 = suicidal thought with detailed plan, and 6 = intentions to conduct plan.ResultsSI was mostly connected to the PE domains perceptual anomalies (PA) and bizarre experiences (BE), which have higher strength values in the network. Central nodes within these domains, as indexed by higher centrality measures (strength and betweenness) were: auditory experiences (PA1: hearing voices when you are alone), persecutory ideation (BE1: feelings of being persecuted; BE2: conspiracy against you), and social anxiety (SA) (SA1: I cannot get close to people).DiscussionThrough a network analytic approach, our results add new insights to previous findings concerning the associations between psychotic experiences and suicidal ideation, suggesting that perceptual anomalies (mainly auditory experiences), social anxiety (being distant to people), and bizarre experiences (paranoid beliefs) are connected in a meaningful way to suicidal ideation in a network of symptoms in a sample of non-help-seeking adolescents. Given the potential advantages of the network analysis to study psychopathology and suicidal behavior, its usage can contribute to a better understanding of the nature of the complex relationships between these phenomena. Future network analysis studies should include additional symptom domains to analyze whether the associations between PE and suicidal behavior are undifferentiated; are specifically and independently associated, regardless of antecedents of mental disorders; or if the associations are not specific, but merely reflect a higher underlying risk of suicidal behavior as a function of psychiatric symptoms or mental distress.

An Online Investigation of Imagery to Attenuate Paranoia in College Students

Onset of psychosis typically occurs in young adulthood, and is likely to be preceded by anxiety, low mood, suspiciousness and perceptual anomalies. Where these develop into mild or brief psychotic experience, and impact on functioning, young people are identified as being at risk of psychosis. Early intervention may reduce severity or delay transition to psychosis, and yield significant healthcare cost savings. This study examined the impact of an online attachment-based imagery task on paranoia, anxiety, mood and self-esteem, in college students. An experimental design was used to compare the effects of secure and anxious-ambivalent attachment imagery. A total of 301 college students, aged 18–48 years (M = 20.1, SD = 2.976), were randomly assigned to one of the two imagery conditions, and assessed pre and post imagery task on standardised measures of paranoia, anxiety, mood and self-esteem. A series of mixed model analyses of variance showed that participants in the secure attachment imagery condition reported lower levels of paranoia, anxiety and negative mood, and higher levels of positive mood and self-esteem, compared with those in the anxious-ambivalent attachment imagery condition. The study is limited by the lack of a neutral control condition and follow-up measures. Nevertheless, study demonstrated the impact of attachment-based imagery on paranoia. If these effects are replicated with ‘at risk mental state’ groups, and maintained at follow-up, online imagery may provide a safe and highly accessible means of attenuating paranoia in young people at risk of developing psychosis.

Sleep quality and paranoia: The role of alexithymia, negative emotions and perceptual anomalies

Recent evidence suggests that sleep problems are associated with psychotic like experiences including paranoia. However, the mechanisms underpinning this association are not well understood and thus studies modelling hypothesised mediating factors are required. Alexithymia, the inability to recognise and describe emotions within the self may be an important candidate. In two separate studies we sought to investigate factors mediating the relationship between sleep quality and paranoia using a cross-sectional design. Healthy volunteers without a mental health diagnosis were recruited (study 1, N = 401, study 2, N = 402). Participants completed a series of measures assessing paranoia, negative emotions, alexithymia and perceptual anomalies in an online survey. In study 1, regression and mediation analyses showed that the relationship between sleep quality and paranoia was partially mediated by alexithymia, perceptual anomalies and negative affect. In contrast, study 2 found that the relationship between sleep quality and paranoia was fully mediated by negative affect, alexithymia and perceptual anomalies. The link between sleep quality and paranoia is unclear and reasons for discrepant results are discussed. Novel findings in this study include the link between alexithymia and paranoia.

Cognitive, affective, and social factors maintaining paranoia in adolescents with mental health problems: A longitudinal study

Paranoia may be a significant concern during adolescence, but there has been little research on excessive mistrust in young people. In this longitudinal study we set out to test the predictive ability of a number of cognitive, affective, and social factors in the early development of paranoia in a clinical adolescent population. Thirty four help-seeking adolescents, aged 11–16 years, reporting paranoid thoughts and attending mental health services were recruited. Self-report and interview assessments of paranoia were conducted at baseline. Measures relating to a cognitive model of persecutory delusions were completed. Paranoia was reassessed after three months with thirty three participants. Significant predictors of paranoia persistence were anxiety, depression, worry, negative self-beliefs, perceptual anomalies, insomnia, affective reactivity, bullying, and cyber victimization. No effect was found for reasoning bias or negative perceptions of academic ability, social competence, and physical appearance. In conclusion, many of the maintenance factors implicated in adult paranoia are likely to prove important in the early development of paranoia in young people. Further experimental and treatment studies are now needed to examine the causal role of these factors in the occurrence of paranoia in adolescents.

Noise-induced and age-related hearing loss: new perspectives and potential therapies.

The classic view of sensorineural hearing loss has been that the primary damage targets are hair cells and that auditory nerve loss is typically secondary to hair cell degeneration. Recent work has challenged that view. In noise-induced hearing loss, exposures causing only reversible threshold shifts (and no hair cell loss) nevertheless cause permanent loss of >50% of the synaptic connections between hair cells and the auditory nerve. Similarly, in age-related hearing loss, degeneration of cochlear synapses precedes both hair cell loss and threshold elevation. This primary neural degeneration has remained a “hidden hearing loss” for two reasons: 1) the neuronal cell bodies survive for years despite loss of synaptic connection with hair cells, and 2) the degeneration is selective for auditory nerve fibers with high thresholds. Although not required for threshold detection when quiet, these high-threshold fibers are critical for hearing in noisy environments. Research suggests that primary neural degeneration is an important contributor to the perceptual handicap in sensorineural hearing loss, and it may be key to the generation of tinnitus and other associated perceptual anomalies. In cases where the hair cells survive, neurotrophin therapies can elicit neurite outgrowth from surviving auditory neurons and re-establishment of their peripheral synapses; thus, treatments may be on the horizon.

Face and Object Perception in Body Dysmorphic Disorder versus Obsessive-Compulsive Disorder: The Mooney Faces Task.

Body dysmorphic disorder (BDD) is characterized by repetitive behaviors and/or mental acts occurring in response to preoccupations with perceived defects or flaws in physical appearance. There are some similarities, but also important differences, between BDD and obsessive-compulsive disorder (OCD), not just in terms of core clinical symptoms, but possibly in the domain of perception. This study compared the nature and extent of perceptual anomalies in BDD versus OCD and health controls (HC), using a modified Mooney task. We included 21 BDD, 19 OCD, and 21 HC participants, who were age-, sex-, and IQ-matched. A set of 40 Mooney faces and 40 Mooney objects arranged in three configurations (i.e., upright, inverted, or scrambled) were presented under brief (i.e., 500 ms) free-viewing conditions. Participants were asked to decide whether each image represented a human face, an object, or neither in a forced-choice paradigm. The BDD group showed significantly reduced face and object inversion effects relative to the other two groups. This was accounted for by BDD participants being significantly more accurate in identifying inverted Mooney faces and objects than the other participants. These data were interpreted as reflecting an overreliance on independent components at the expense of holistic (configural) processing in BDD. (JINS, 2017, 23, 471-480).

Binaural Diplacusis and Its Relationship with Hearing-Threshold Asymmetry.

Binaural pitch diplacusis refers to a perceptual anomaly whereby the same sound is perceived as having a different pitch depending on whether it is presented in the left or the right ear. Results in the literature suggest that this phenomenon is more prevalent, and larger, in individuals with asymmetric hearing loss than in individuals with symmetric hearing. However, because studies devoted to this effect have thus far involved small samples, the prevalence of the effect, and its relationship with interaural asymmetries in hearing thresholds, remain unclear. In this study, psychometric functions for interaural pitch comparisons were measured in 55 subjects, including 12 normal-hearing and 43 hearing-impaired participants. Statistically significant pitch differences between the left and right ears were observed in normal-hearing participants, but the effect was usually small (less than 1.5/16 octave, or about 7%). For the hearing-impaired participants, statistically significant interaural pitch differences were found in about three-quarters of the cases. Moreover, for about half of these participants, the difference exceeded 1.5/16 octaves and, in some participants, was as large as or larger than 1/4 octave. This was the case even for the lowest frequency tested, 500 Hz. The pitch differences were weakly, but significantly, correlated with the difference in hearing thresholds between the two ears, such that larger threshold asymmetries were statistically associated with larger pitch differences. For the vast majority of the hearing-impaired participants, the direction of the pitch differences was such that pitch was perceived as higher on the side with the higher (i.e., ‘worse’) hearing thresholds than on the opposite side. These findings are difficult to reconcile with purely temporal models of pitch perception, but may be accounted for by place-based or spectrotemporal models.

Early perceptual anomaly of negative facial expression in depression: An event-related potential study

Depressed patients have a demonstrated cognitive bias in emotional information processing. However, it is unknown how early perceptual processing is modulated by emotional stimuli in depression. To examine this question, we studied 22 depressed patients and 22 healthy controls performing a cued target-response task with emotional facial expression as the cue. The early perceptual processes were examined using event-related potential (ERP) components, i.e., P1 and N170. Results showed that depressed patients had larger P1 amplitudes than healthy controls, implying that early perceptual abnormality for face processing in depression may occur as early as the P1 stage. There was no significant interaction between emotion types and groups on P1 amplitudes, which suggested that cognitive biases in depression might not yet have arisen. Following the P1 stage, N170 amplitudes for sad faces were larger than for other emotion types in depressed patients, whereas N170 amplitudes for happy faces were larger than for other emotion types in healthy controls. These results implied that depressed patients might have a perceptual bias associated with sad emotions, which may be detectable from the N170 time window. In summary, this study provides new insights for understanding the negative cognitive bias in depression using the electroneurophysiological biomarker N170.

The Nature of Science

I wrote a letter to Microbe, published in the October 2010 issue, p. 412–413, that discussed the similar erroneous prejudices that scientists of the applied and research fields often hold for each other. With this letter I would like to discuss other perceptual anomalies scientists have grown to embrace. They relate to exactly what science is in the minds of scientists.