Richard J Stevenson

Publications of Richard J Stevenson

• Source Monitoring and Olfactory Hallucinations in Schizophrenia.

  Authors: Deborah Arguedas, Richard J Stevenson, Robyn Langdon

  Journal of abnormal psychology. 03/2012;

  People with schizophrenia who experience auditory-verbal hallucinations experience difficulty in determining the source (self vs. other) of verbal information, and those with visual hallucinationsPeople with schizophrenia who experience auditory-verbal hallucinations experience difficulty in determining the source (self vs. other) of verbal information, and those with visual hallucinations experience a conceptually similar problem with visual information. In this study, we examined whether such source monitoring deficits extend to olfaction for olfactory hallucinators and whether they are selective to the modality in which the hallucination is experienced. To test these claims, three groups were formed: normal controls (NC), people with schizophrenia who experience olfactory hallucinations (OH), and people with schizophrenia who experience auditory-verbal hallucinations (AVH). These three groups were then tested on both an olfactory and an auditory-verbal source-monitoring task. We found evidence of a modality-specific impairment. The OH group was less accurate in determining whether an odor had been imagined or smelled relative to NC and AVH groups. In contrast, the AVH group was least accurate in determining the source of a word, relative to the OH and NC groups. These findings provide the first evidence of a source-monitoring impairment in schizophrenic participants with OHs and suggest that this impairment is modality specific. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

• A preliminary investigation of olfactory function in olfactory and auditory-verbal hallucinators with schizophrenia, and normal controls.

  Authors: Richard J Stevenson, Robyn Langdon

  Cognitive neuropsychiatry. 12/2011;

  Introduction. It is well established that people with schizophrenia have impaired olfactory perception. However, another olfactory abnormality that occurs in schizophrenia-olfactory hallucinationsIntroduction. It is well established that people with schizophrenia have impaired olfactory perception. However, another olfactory abnormality that occurs in schizophrenia-olfactory hallucinations (OHs)-has received almost no attention. Methods. This preliminary study compared a small sample of olfactory (OH; n=14) and auditory-verbal (AVH; n=11) hallucinators with schizophrenia, with matched healthy controls (NC; n=21), on tests of odour detection threshold, identification, and hedonics, and bespoke tests relating to possible causes of OHs. Results. Both OH and AVH participants were equally impaired on tests of odour identification, but neither had any impairment in detection. However, although the AVH group had hedonic impairments, these were not evident in the OH and NC groups. Examination of the possible causes of OHs revealed abnormalities in olfactory habituation. In addition, we observed a far greater rate of past episodes of brief unconsciousness in the OH group. Conclusions. The presence of habituation deficits and past episodes of brief unconsciousness, and absence of olfactory affective impairment, have not been identified before as correlates of OHs, suggesting these factors may be worthy of further investigation.

• Disease avoidance as a functional basis for stigmatization.

  Authors: Megan Oaten, Richard J Stevenson, Trevor I Case

  Philosophical transactions of the Royal Society of London. Series B, Biological sciences. 12/2011; 366(1583):3433-52.

  Stigmatization is characterized by chronic social and physical avoidance of a person(s) by other people. Infectious disease may produce an apparently similar form of isolation-disease avoidance-butStigmatization is characterized by chronic social and physical avoidance of a person(s) by other people. Infectious disease may produce an apparently similar form of isolation-disease avoidance-but on symptom remission this often abates. We propose that many forms of stigmatization reflect the activation of this disease-avoidance system, which is prone to respond to visible signs and labels that connote disease, irrespective of their accuracy. A model of this system is presented, which includes an emotional component, whereby visible disease cues directly activate disgust and contamination, motivating avoidance, and a cognitive component, whereby disease labels bring to mind disease cues, indirectly activating disgust and contamination. The unique predictions of this model are then examined, notably that people who are stigmatized evoke disgust and are contaminating. That animals too show avoidance of diseased conspecifics, and that disease-related stigma targets are avoided in most cultures, also supports this evolutionary account. The more general implications of this approach are then examined, notably how it can be used to good (e.g. improving hygiene) or bad (e.g. racial vilification) ends, by yoking particular labels with cues that connote disease and disgust. This broadening of the model allows for stigmatization of groups with little apparent connection to disease.

• Proactive strategies to avoid infectious disease.

  Authors: Richard J Stevenson, Trevor I Case, Megan J Oaten

  Philosophical transactions of the Royal Society of London. Series B, Biological sciences. 12/2011; 366(1583):3361-3.

  Infectious disease exerts a large selective pressure on all organisms. One response to this has been for animals to evolve energetically costly immune systems to counter infection, while another--theInfectious disease exerts a large selective pressure on all organisms. One response to this has been for animals to evolve energetically costly immune systems to counter infection, while another--the focus of this theme issue--has been the evolution of proactive strategies primarily to avoid infection. These strategies can be grouped into three types, all of which demonstrate varying levels of interaction with the immune system. The first concerns maternal strategies that function to promote the immunocompetence of their offspring. The second type of strategy influences mate selection, guiding the selection of a healthy mate and one who differs maximally from the self in their complement of antigen-coding genes. The third strategy involves two classes of behaviour. One relates to the capacity of the organisms to learn associations between cues indicative of pathogen threat and immune responses. The other relates to prevention and even treatment of infection through behaviours such as avoidance, grooming, quarantine, medicine and care of the sick. In humans, disease avoidance is based upon cognition and especially the emotion of disgust. Human disease avoidance is not without its costs. There is a propensity to reject healthy individuals who just appear sick--stigmatization--and the system may malfunction, resulting in various forms of psychopathology. Pathogen threat also appears to have been a highly significant and unrecognized force in shaping human culture so as to minimize infection threats. This cultural shaping process--moralization--can be co-opted to promote human health.

• Limits to knowing in olfaction.

  Authors: Richard J Stevenson

  Consciousness and cognition. 12/2011; 21(1):593-4.

• Discriminating the stimulus elements during human odor-taste learning: a successful analytic stance does not eliminate learning.

  Authors: Richard J Stevenson, Mehmet K Mahmut

  Journal of experimental psychology. Animal behavior processes. 10/2011; 37(4):477-82.

  Odor "sweetness" may arise from experiencing odors and tastes together, resulting in a flavor memory that is later reaccessed by the odor. Forming a flavor memory may be impaired if the taste andOdor "sweetness" may arise from experiencing odors and tastes together, resulting in a flavor memory that is later reaccessed by the odor. Forming a flavor memory may be impaired if the taste and odor elements are apparent during exposure, suggesting that configural processing may underpin learning. Using a new procedure, participants made actual flavor discriminations for one odor-taste pair (e.g., Taste A vs. Odor X-Taste A) and mock discriminations for another (e.g., Odor Y-Taste B vs. Odor Y-Taste B). Participants, who were successful at detecting the actual flavor discriminations, demonstrated equal amounts of learning for both odor-taste pairings. These results suggest that although a capacity to discriminate flavor into its elements may be necessary to support learning, whether participants experience a configural or elemental flavor representation may not.

• Disease-avoidant behaviour and its consequences.

  Authors: Daria Kouznetsova, Richard J Stevenson, Megan J Oaten, Trevor I Case

  Psychology & health. 08/2011;

  Medical conditions that are non-contagious, but that appear contagious, seem to result in the sufferer being avoided. Error management theory (EMT), suggests that such false alarms occur because theMedical conditions that are non-contagious, but that appear contagious, seem to result in the sufferer being avoided. Error management theory (EMT), suggests that such false alarms occur because the cost of infection poses a greater threat to ones fitness than avoidance. Study 1 attempted to demonstrate a disease-related false alarm effect by asking participants, to evaluate a series of vignettes, featuring people with infectious diseases, non-infectious diseases that looked infectious and non-infectious diseases that did not. Judgements of contracting infection under varying levels of contact, and desire to avoid were obtained. Consistent with EMT, a false alarm effect was evident. Study 2 examined the importance of the face as a key indicator of real and apparent infection, by determining whether facial symptoms result in a greater desire to avoid people with infectious and non-infectious diseases. Consistent with expectation, participants reported a greater desire to avoid people with facially displayed symptoms. Together, these results support the idea that humans have evolved a general tendency to avoid individuals with disease signs, especially if displayed upon the face. One consequence is that where a facially displayed disease sign persists, even if known to be benign, its bearer will experience chronic avoidance.

• The impact of mediodorsal thalamic lesions on olfactory attention and flavor perception.

  Authors: Wendy W P Tham, Richard J Stevenson, Laurie A Miller

  Brain and cognition. 06/2011; 77(1):71-9.

  Olfactory attention may be important in generating odor-induced tastes - an arguably universal form of synesthesia - by ensuring that the taste concurrent is captured by the nose and olfaction, notOlfactory attention may be important in generating odor-induced tastes - an arguably universal form of synesthesia - by ensuring that the taste concurrent is captured by the nose and olfaction, not by the mouth and gustation (oral-capture). To examine the role of olfactory attention in generating odor-induced tastes and oral capture we tested a small sample (n=4) of participants with likely impairments in olfactory attention - individuals with mediodorsal thalamic nucleus (MDNT) lesions. These participants were compared to two sets of controls on tests of olfactory attention, oral capture, odor and flavor perception, and control tasks. MDNT participants demonstrated impaired olfactory attention and enhanced oral capture. Greater oral capture was associated with greater olfactory attentional impairment. These findings imply that olfactory attention may be important in attributing odor-induced tastes to the olfactory modality. However, unlike for visual binding and for the neurodevelopmental synesthesias, where attention may be necessary to demonstrate both phenomena, olfactory attention deficits did not impair flavor binding or the experience of odor-induced tastes.

• Olfactory illusions: where are they?

  Authors: Richard J Stevenson

  Consciousness and cognition. 06/2011; 20(4):1887-98.

  It has been suggested that there maybe no olfactory illusions. This manuscript examines this claim and argues that it arises because olfactory illusions are not typically accompanied by an awarenessIt has been suggested that there maybe no olfactory illusions. This manuscript examines this claim and argues that it arises because olfactory illusions are not typically accompanied by an awareness of their illusory nature. To demonstrate that olfactory illusions do occur, the relevant empirical literature is reviewed, by examining instances of where the same stimulus results in different percepts, and of where different stimuli result in the same percept. The final part of the manuscript evaluates the evidence favoring the existence of olfactory illusions, and then examines why they may not typically be accompanied by awareness. Three contributory mechanisms are discussed, relating to difficulty of verification and paucity of olfactory knowledge, the role of change blindness, and restricted access consciousness in this sense.

• Olfactory test performance and its relationship with the perceived location of odors.

  Authors: Richard J Stevenson, Mehmet K Mahmut

  Attention, perception & psychophysics. 04/2011; 73(6):1966-76.

  Odors are generally perceived as arising via the nose when sniffed and as part of an orally located flavor during ingestion. The perceived location of an odor may in part be an attentionalOdors are generally perceived as arising via the nose when sniffed and as part of an orally located flavor during ingestion. The perceived location of an odor may in part be an attentional phenomenon, with concurrent oral stimulation occurring at the expense of access to the olfactory channel. Two predictions were derived from this account: (a) tasks dependent on a capacity to attend to the olfactory channel--odor discrimination and naming--should be adversely affected by oral localization; and (b) tasks not dependent upon a capacity to attend--incidental learning/recognition memory--should not. Using a procedure to generate oral localization, in which odors were presented via the nose with concurrent oral stimulation (sucrose, a viscous fluid or water), greater reported oral localization was associated with poorer odor discrimination and naming, but not with recognition memory performance. These results support the notion that attentional processes contribute to oral localization of odors by reducing the capacity to attend to the olfactory channel.

• Validating the factor structure of the Self-Report Psychopathy scale in a community sample.

  Authors: Mehmet K Mahmut, Con Menictas, Richard J Stevenson, Judi Homewood

  Psychological assessment. 04/2011; 23(3):670-8.

  Currently, there is no standard self-report measure of psychopathy in community-dwelling samples that parallels the most commonly used measure of psychopathy in forensic and clinical samples, theCurrently, there is no standard self-report measure of psychopathy in community-dwelling samples that parallels the most commonly used measure of psychopathy in forensic and clinical samples, the Psychopathy Checklist. A promising instrument is the Self-Report Psychopathy scale (SRP), which was derived from the original version the Psychopathy Checklist. The most recent version of the SRP (SRP-III; D. L. Paulhus, C. S. Neumann, & R. D. Hare, in press) has shown good convergent and discriminate validity and a factor structure similar to the current version of the Psychopathy Checklist (PCL-R; R. D. Hare, 1991, 2003). The analyses in the current study further investigated the viability of the SRP-III as a PCL-R-analogous measure of psychopathy in nonforensic and nonclinical samples by extending the validation process to a community sample. Using confirmatory factor analyses and logistic regressions, the results revealed that a four-factor oblique model for the SRP-III was most tenable, congruent with the PCL-R factor structure of psychopathy and previous research in which the SRP-III was administered to a student sample.

• Olfactory hallucinations in schizophrenia and schizoaffective disorder: a phenomenological survey.

  Authors: Richard J Stevenson, Robyn Langdon, Jonathan McGuire

  Psychiatry research. 02/2011; 185(3):321-7.

  Olfactory hallucinations (OHs), so it has been argued, are prognostic of a poorer outcome, are unpleasant, and cannot be well explained within current theoretical accounts of hallucinations. WeOlfactory hallucinations (OHs), so it has been argued, are prognostic of a poorer outcome, are unpleasant, and cannot be well explained within current theoretical accounts of hallucinations. We examined these and related issues by conducting structured interviews with 51 participants who experienced OHs and who were previously diagnosed with schizophrenia or schizoaffective disorder. We found no relationship between disease severity measures and type or frequency of OHs. As with prior research, we too noted the predominance of negative OHs, but with many reports of positive OHs, and also found significant relationships between frequency of OHs and severity of tactile hallucinations. We then examined whether odor imagery or involuntary memory might account for the presence of OHs, but these possibilities were not well supported. We then explored, using cluster analysis, whether or not our sample was homogenous. Two clusters were of especial interest; one which may reflect a 'sensory dysfunction group' and one characterized by more severe tactile hallucinations. The presence of tactile hallucinations may suggest a further novel cause of OHs, which we discuss. Our data suggest diverse causes for OHs in schizophrenia, none of which are consistent with current models of hallucinations in other modalities.

• The role of taste and oral somatosensation in olfactory localization.

  Authors: Richard J Stevenson, Megan J Oaten, Mehmet K Mahmut

  Quarterly journal of experimental psychology (2006). 02/2011; 64(2):224-40.

  Although there is only one set of olfactory receptors, odours are experienced as smells when sniffing things (e.g., sniffing a wine's bouquet) and as flavours when the olfactory stimulus is presentAlthough there is only one set of olfactory receptors, odours are experienced as smells when sniffing things (e.g., sniffing a wine's bouquet) and as flavours when the olfactory stimulus is present in the mouth (e.g., drinking wine). How this location binding--external versus internal environment--is achieved is poorly understood. Experiment 1 employed a new procedure to study localization, which was then used to explore whether localization is primarily dependent upon simultaneous oral somatosensation. Experiment 2, using solutions of varying viscosity, and Experiment 3, using oral movement of varying vigour, revealed that sniffed odours are not localized to the mouth by somatosensation alone. Instead, Experiment 4 demonstrated that a tastant needs to be present and that increasing tastant concentration generates increasing oral localization. Experiment 5 found that this reliance upon gustation reflects the previously observed "confusion" that people show for taste and smell stimuli in the mouth. We suggest that this "confusion" reflects the gustatory system's superior ability to suppress olfactory attention, thus assisting flavour binding.

• The role of attention in the localization of odors to the mouth.

  Authors: Richard J Stevenson, Mehmet K Mahmut, Megan J Oaten

  Attention, perception & psychophysics. 01/2011; 73(1):247-58.

  Odors can be perceived as arising from the environment or as part of a flavor located in the mouth. One factor that may dictate where an odor is perceived to be is concurrent gustatory stimulation inOdors can be perceived as arising from the environment or as part of a flavor located in the mouth. One factor that may dictate where an odor is perceived to be is concurrent gustatory stimulation in the mouth. A taste may impair the ability to attend to an odor, especially if they are perceptually similar. Alternatively, salient mouth-based features of a flavor might command attention at the expense of smell. Experiment 1 and 2, using different stimulus sets, explored the impact of perceptually similar and dissimilar pairings of tastes in the mouth and odors at the nose. In each case, these were followed by judgments of the odor's location (mouth vs. nose). Perceptual similarity had no impact on localization judgments. Experiment 3 then manipulated the salience of the olfactory and gustatory cues and showed that each could independently shift the perceived location of an odorant-salient olfactory cues toward the nose and gustatory cues toward the mouth. These findings suggest that the salient features of a flavor may command attention at the expense of olfaction and, thereby, contribute to oral localization, with implications for flavor binding.

• The role of the mediodorsal thalamic nucleus in human olfaction.

  Authors: Wendy W P Tham, Richard J Stevenson, Laurie A Miller

  Neurocase. 01/2011; 17(2):148-59.

  Olfaction has a unique dual-route pathway to the neocortex - one being via the mediodorsal nucleus of the thalamus (MDNT). In this study we explored the role of the MDNT pathway, by comparing sixOlfaction has a unique dual-route pathway to the neocortex - one being via the mediodorsal nucleus of the thalamus (MDNT). In this study we explored the role of the MDNT pathway, by comparing six patients with MDNT lesions, with 14 controls, on tests of general olfactory ability (i.e., odor acuity, discrimination, naming, recognition memory and hedonic judgement), visual control and neuropsychological tests, and tests of olfactory attention. The MDNT patients performed normally on most general olfactory tests but showed varying impairments on tests of olfactory attention. These findings suggest that the MDNT pathway is involved, either specifically or generically, in mediating human olfactory attention.

• The effect of disgust on oral immune function.

  Authors: Richard J Stevenson, Deborah Hodgson, Megan J Oaten, Javad Barouei, Trevor I Case

  Psychophysiology. 12/2010; 48(7):900-7.

  Disgust motivates avoidance of pathogen sources, but whether its role in disease avoidance extends into activating the immune system is unexplored. This was tested here by comparing oral immuneDisgust motivates avoidance of pathogen sources, but whether its role in disease avoidance extends into activating the immune system is unexplored. This was tested here by comparing oral immune markers before and after a disgust induction, relative to neutral and negative induction control groups. The disgust group, but not controls, revealed an oral inflammatory response, with increased salivary tumor necrotizing factor alpha and albumin, as well as a down-regulation of immunoglobulin A (SIgA) secretion. It has been hypothesized that disgust evolved in animals to clear toxins from the oral cavity by gaping and increased salivary flow. Our data suggest down-regulated SIgA secretion may be a vestige of this response so as to conserve protein, while the inflammatory reaction may reflect an adaptive response to disease threat, selectively triggered by disgust. The broader implications of these data for a discrete neuro-gut-immune axis are examined.

• Differential context effects between sweet tastes and smells.

  Authors: Richard J Stevenson, Mehmet Mahmut

  Attention, perception & psychophysics. 11/2010; 72(8):2304-13.

  "Sweet" smells and tastes are perceptually similar, and physiological data indicate some commonality of central processing. However, sweet tastes and sweet smells do not provide interchangeable"Sweet" smells and tastes are perceptually similar, and physiological data indicate some commonality of central processing. However, sweet tastes and sweet smells do not provide interchangeable contexts in psychophysical experiments. The same sweet tastes are perceived as less intense when stronger sweet tastes are present, and they are perceived as more intense when weaker sweet tastes are present, as with sweet smells. However, complementary sets of sweet tastes and smells (e.g., weak sweet tastes, strong sweet smells) do not eliminate these differential context effects (DCEs). The present experiments examined, first, whether DCEs between sweet tastes and smells arise because of differences between odors and tastes in the way that sweetness scales with intensity as concentration rises, and, second, whether DCEs may be smaller for sweet tastes and smells, when contrasted with sweet tastes and nonsweet smells. The findings were clear: DCEs were consistently present, suggesting they are independent of perceptual similarity. These results imply that DCEs are probably not psychological in origin or centrally based; rather, they may have a subcortical locus.

• Experience dependent changes in odour-viscosity perception.

  Authors: Richard J Stevenson, Mehmet K Mahmut

  Acta psychologica. 10/2010; 136(1):60-6.

  One consequence of experiencing flavour - the combination of taste, smell and somatosensation that occurs during ingestion - is that it can result in perceptual changes for the odour component, whenOne consequence of experiencing flavour - the combination of taste, smell and somatosensation that occurs during ingestion - is that it can result in perceptual changes for the odour component, when this is later smelled alone. One such change is the acquisition of taste-like properties, but whether odours can also acquire somatosensory-like qualities is largely unknown. Participants here were exposed to one odour sampled in a viscous solution, another sampled in a sweet/viscous solution, and a further odour sampled in water. The odour sampled in the sweet/viscous solution was, when later sniffed alone, judged to smell thicker and sweeter, than the other two odours. Similarly, when the sweet/viscous paired odour was added to a viscous solution, the combination was judged as more viscous, than the other two odours - and sweeter when added to a sweet solution. This experiment suggests that odours can acquire tactile-like somatosensory qualities and this may best occur when a taste is present during learning. Recent work indicates that tastes may be superior to somatosensory stimuli alone in promoting flavour binding, a seeming precondition for this type of learning.

• Sweet odours and sweet tastes are conflated in memory.

  Authors: Richard J Stevenson, Megan J Oaten

  Acta psychologica. 05/2010; 134(1):105-9.

  Certain odours and certain tastes appear to share common perceptual properties. One example is sweetness, a perceptual experience that results from stimulation of taste receptors on the tongueCertain odours and certain tastes appear to share common perceptual properties. One example is sweetness, a perceptual experience that results from stimulation of taste receptors on the tongue typically by sugars. The experiment here examined for evidence of this perceptual similarity using a novel and indirect test. Participants were exposed six times each, to three odours (strawberry, caramel, and oregano) and three tastes (sucrose, saline, and citric acid). Following a 10-min interval, participants were given a surprise frequency estimation task, in which they had to judge how often each stimulus had occurred. If sweet-smelling strawberry and caramel odours really do share this perceptual characteristic in common with sweet tasting sucrose, then frequency estimates for sucrose should be overestimated relative to non-sweet tastes. Not only was this observed, but frequency estimates for sweet tastes were also found to correlate with (1) evaluations from a later test of similarity between these sweet smells and sucrose, and (2) the degree to which these odours smelled sweet. These findings suggest a shared perceptual feature between such odours and sucrose - sweetness - under conditions where no judgment of perceptual quality was required.

• Children's response to adult disgust elicitors: development and acquisition.

  Authors: Richard J Stevenson, Megan J Oaten, Trevor I Case, Betty M Repacholi, Paul Wagland

  Developmental psychology. 01/2010; 46(1):165-77.

  Little is known about when or how different disgust elicitors are acquired. In Study 1, parents of children (0-18 years old) rated how their child would react to 22 disgust elicitors. DifferentLittle is known about when or how different disgust elicitors are acquired. In Study 1, parents of children (0-18 years old) rated how their child would react to 22 disgust elicitors. Different developmental patterns were identified for core, animal, and sociomoral elicitors, with core elicitors emerging first. In Study 2, children (2-16 years old) were exposed alone and then with their parent to a range of elicitors derived from Study 1. Self-report, behavioral, and facial expression data were obtained along with measures of contagion, conservation, and contamination. Convergent evidence supported the developmental patterns reported in Study 1. Evidence for parent-child transmission was also observed, with parents of young children emoting more disgust to their offspring and showing greater behavioral avoidance. Moreover, child reactivity to animal and sociomoral elicitors and contamination correlated with parental responsiveness. Finally, young children who failed to demonstrate contagion and conservation knowledge were as reactive to core elicitors and contamination as children of the same age who demonstrated such knowledge. These findings are interpreted within an evolutionary framework in which core disgust responses are acquired early to promote avoidance of pathogens.