The Dame Mira Szászy School of Psychology - Leading psychological science, scholarship and practice


CNRG basic research

Attention


Attentional Blink (Hamm)

The attentional blink refers to the failure to detect a probe letter if it closely follows a target letter that must be identified.  We have demonstrated that the attentional blink appears to be modulated by the semantic relationship between the identified target and the probe item. For example, if the target items is a letter, and the probe is O, then the probe will "blink" (be missed) if subjects are told it is the letter "oh". However, if they are told they are looking for the digit "zero", the blink is greatly reduced. This suggests that the attentional blink may be more related to a form of semantic interference than to visual attention, and hence may be misnamed. More recent work has shown that the attentional blink appears to be left lateralised, and possibly reflects decreased activity in the left temporal lobe.

  • Holländer A, Hausmann M, Hamm JP, Corballis MC. (2005). Sex hormonal modulation of hemispheric asymmetries in the attentional blink. J Int Neuropsychol Soc,11, 263-72.
  • Holländer A, Corballis MC, Hamm JP. (2005). Visual-field asymmetry in dual-stream RSVP. Neuropsychologia, 43, 35-40.


Neural correlates underlying Stroop task performance (Kirk/Waldie)

We use high density EEG to record visual-evoked potentials from healthy subjects while performing different versions of the Stroop task. Understanding the biological basis of this measure of selective attention is more than simply academic interest, due to the utility of the Stroop as a classification measure for disorders such as schizophrenia, ADHD, mania, anxiety, and Alzheimer's disease. 

  • Badzakova-Trajkov, G., Barnett, K.J., Waldie, K.E., & Kirk, I.J. An ERP investigation of the Stroop task: The role of the cingulate in attentional allocation and conflict resolution. Brain Research,1253, 139-148, 2009.
  • Barnett KJ, Fairhall SL, Badzakova G, Morton AC, Kirk IJ. Involvement of anterior cingulate and lateral prefrontal cortices in the Stroop colour-word task: Evidence from complementary EEG and fMRI studies. In CM Fletcher Flynn & GM Haberman (Eds) Cognition, Language and Development: Perspectives from New Zealand. Bowen Hills, Queensland: Australian Academic Press pp. 65-79 (2006).


Non-conscious effects of peripheral information on visual orienting (Lambert)

Previous research has suggested that visual orienting can occur in two ways: either under voluntary control, or reflexively in response to salient visual changes in the periphery. Work from my laboratory suggests that this simple dichotomy between reflexive and voluntary orienting does not do justice to the exquisite design of the human perceptual system. Several conclusions can be drawn from our recent research. (1) Visual orienting can be influenced not only by the gross visual changes that elicit reflexive orienting, but also by the nature of information appearing in the periphery; (2) Individuals can orient appropriately in response to peripheral information while remaining unaware of the utility of that information in guiding the attention shift; (3) Individuals can orient appropriately in response to peripheral stimuli, while remaining unaware that any stimulus at all has been presented; (4) Visual orienting can be influenced not only by the visual form of briefly presented peripheral objects, but also by semantic characteristics of the object.

  • Lambert, A., Roser, M., Wells, I., & Heffer, C. (2006). The spatial correspondence hypothesis and orienting in response to central and peripheral spatial cues. Visual Cognition, 13, 65-88.
  • Kean, M., & Lambert, A. (2003). The influence of a salience distinction between bilateral cues on the latency of target-detection saccades. British Journal of Psychology, 94, 373-388.
  • Lambert, A., Wells, I., & Kean, M. (2003). Do isoluminant color changes capture attention? Perception & Psychophysics, 65, 495-507.
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Emotion


Emotion and Cognition (Lambert)

I am currently undertaking two projects in this area. The first project is studying patterns of eye movements as participants scan scenes which vary in emotionality. The second project, being carried out in collaboration with A/P Ian Kirk, is examining the neural correlates of memory suppression of emotional material, using advanced functional magnetic resonance imaging. Findings from both projects will provide valuable information concerning the impact of emotional factors on the cognitive processes of attention and memory. 


Age-related Changes in Emotional Memory (Addis)

In a research collaboration with Dr Elizabeth Kensinger (Boston College), we are examining how emotional memory processes change with age. Older adults often show sustained attention toward positive information and an improved memory for positive events. Using fMRI, we examined connectivity amongst brain regions during the encoding of positive and negative stimuli. Our findings suggest that older adults' "positivity effect" may arise from age-related changes in the interactions between affect-processing regions and the hippocampus during the encoding of positive information.

  • Addis, D.R., Leclerc, C.M., Muscatell, K., Kensinger, E.A. (2010). There are age-related changes in neural connectivity during the successful encoding of positive, but not negative, information. Cortex, 46, 425-433.
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Language


Evolution of Language (Corballis)

Arising from my interest in the connection between handedness and cerebral asymmetry for language, I have developed an old idea that language evolved from manual gestures rather than from animal calls. This idea is supported by studies of the role of manual gesture in normal speech, by investigations of signed languages developed by deaf communities, by attempts to reach language to nonhuman primates, and by evidence that the homologues of the speech areas in nonhuman primates has to go with manual action rather than with vocalization. My current endeavour is to provide a plausible account of how the transition might have occurred, based on the premise that speech itself is a gestural system rather than an acoustic one.

  • Corballis, M.C. (2003). From mouth to hand: Gesture, speech, and the evolution of right-handedness. Behavioral and Brain Sciences, 26, 199-208.
  • Corballis, M. C. (2009). The evolution of language. Annals of the New York Academy of Sciences, 1156, 19-43.


Expansion of Austronesian Languages (Gray)

The Austronesian language family is one of the largest in the world, and one of the most widely dispersed, with around 1,200 languages spoken in the area between Madagascar, Taiwan, Hawaii, Easter Island and NZ. Our research uses phylogenetic methods to test hypotheses about the expansion of the Austronesian language family and the settlement of the Pacific. By placing genetic and linguistic evidence in a common methodological framework we hope to be able to make more powerful inferences about our past. We analysed basic vocabulary from 400 languages in this database using computational phylogenetic methods to build a set of "family" trees for the languages of the Pacific. The results clearly show that the origin of the entire Austronesian language family can be dated back to Taiwan around 5,200 years ago, and moved through Island South-East Asia, along New Guinea and into Polynesia.

  • Gray, R.D., Drummond, A.J., Greenhill, S.J. (2009) Language Phylogenies Reveal Expansion Pulses and Pauses in Pacific Settlement. Science, 323, 479-483.
  • Gray, R.D. (2005) Pushing the time barrier in the quest for language roots. Science, 209, 307-308.
  • Gray, R.D., Jordan, F.M. (2000) Language trees support the express-train sequence of Austronesian expansion. Nature, 405, 1052-1055.


Biological Basis of Reading (Waldie)

The left hemisphere is primarily responsible for speech expression, reception and reading; however there is now evidence that the right hemisphere is also actively involved in reading processes. We investigate the role of the right hemisphere using brain imaging techniques in healthy adults.

  • Waldie, K.E. (2005) Introduction to developmental neuroscience: Neurological development and the mechanisms underlying reading. In Jason Low and Paul Jose (Eds.) Lifespan Development: The New Zealand Context (pp.20-30). Auckland, Pearson.
  • Waldie, K.E. (2002). Reading with the right hemisphere: From normal development to dysphonetic dyslexia. In Serge P. Shohov (Ed.) Advances in Psychology Research (Vol 9, pp 157-184). New York: Nova Science Publishers, Inc.
  • Waldie, K.E., Mosley, J.L. (2000). Hemispheric specialization for reading. Brain and Language, 75, 108-122.
  • Waldie, K.E., Mosley, J.L. (2000). Developmental trends in right hemispheric participation in reading. Neuropsychologia, 38, 462-474.
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Lateralisation


Cerebral Asymmetry and Interhemispheric Integration (Corballis)

Our research has focussed on the mechanisms via which some visual information is able to be transferred between the disconnected hemispheres in split brain patients. Our results suggest an important role for subcortical structures in this process.

  • Corballis, M. C.  (2009). The evolution and genetics of cerebral asymmetry. Philosophical Transactions of the Royal Society of London B: Biological Sciences, 364, 867-879.
  • Corballis, M. C. (2007). The dual-brain myth. In S. Della Sala (Ed.), Tall tales about the mind & brain: Separating fact from fiction. New York, NY: Oxford University Press.
  • Corballis, M. C., Barnett, K. J., Fabri, M., Paggi, A., & Corballis, P. M. (2004). Hemispheric integration and differences in perception of a line-motion illusion in the divided brain. Neuropsychologia, 42, 1852-1857.


The Effects of Callosal Maturation and Damage on Laterality (Waldie)

Normal adults tend to bisect horizontal lines to the left of the objective middle, especially when using the left hand. This bias has been attributed to the dominance of the right hemisphere in spatial attention. We have used this task in children and adults, and results suggest a shift from contralateral to right-hemispheric control during puberty that may reflect maturation of the corpus callosum. We have also administered this task to left- and right-hemispherectomized patients with contralateral hemianopia, and found that relative to control participants, hemispherectomized patients showed a strong bisection bias towards their blind visual field. This contralateral bias persisted when patients were forced to start scanning within their blind hemifield, supporting the idea of a strategic adaptation of attention towards the blind visual field.

  • Hausmann, M.,Waldie, K.E., Allison, S.D., Corballis, M.C. (2003). Line bisection following hemispherectomy. Neuropsychologia, 41, 1523-1530.
  • Hausmann, M.,Waldie, K.E., Corballis, M.C. (2003). Developmental changes in line bisection: A result of callosal maturation? Neuropsychology, 17, 155-160.
  • Franz, E.A., Waldie, K.E., Smith, M.J. (2000). The effect of callosotomy on novel versus familiar bimanual actions: A neural dissociation between controlled and automatic processes? Psychological Science, 11, 82-85.


The Effect of Handedness and Sex on Interhemispheric Transfer (Kirk)

Visual detection tasks such as the Poffenberger paradigm can be coupled with electroencephalography (EEG) to investigate interhemispheric transfer differences between left- and right-handed males. We also employ diffusion tensor imaging (DTI) to study handedness effects with microstructural properties of the corpus callosum, which enables interhemispheric transmission. We revealed that the pattern of interhemispheric transfer differs between left- and right-handed males, which may be explained with reference to lateralization of cognitive functions. The comparable overall transfer time of the two groups is consistent with the finding of similar structural integrity of the callosal fibres in both groups, which demonstrates a significant link between structure and function. Both EEG and DTI have proven to be effective methods for investigating interhemispheric functioning and have provided further insight into the effects of handedness on the function of the corpus callosum. Sex hormones may also have an effect on interhemispheric transfer and laterality. This research is conducted in collaboration with Dr Markus Hausmann (Durham University), Dr Karen Waldie and Prof Michael Corballis, and is funded by AURC.

  • Iwabuchi S.J., Kirk I.J. (2009) Atypical interhemispheric communication in left-handed individuals.  NeuroReport, 20, 166-169.


Laterality and Bilingualism (Waldie)

We have investigated hemispheric specialisation for both first (L1) and second (L2) language in late proficient bilinguals living in the L2 environment. A dual task, consisting of speeded tapping during concurrent silent and aloud reading, was employed. The data indicate more bilateral hemispheric involvement for both L2 and L1 in late proficient bilinguals living in the L2 environment.

  • Badzakova-Trajkov, G., Kirk, I.J., Waldie, K.E. (2008). Dual-Task performance in late proficient bilinguals. Laterality: Asymmetries of Body, Brain, and Cognition, 13, 201-216.


Lateralisation and Expertise (Tippett)

In collaboration with Dr Lucy Patston, we have examined the effect of musical expertise and training on the lateralisation of visuospatial processing. Attention in healthy adults normally errs towards the left side of space, as documented in studies involving tasks of visual attention (i.e., line bisection). While musicians and non-musicians both perform more accurately to left-sided stimuli, musicians are significantly more accurate than non-musicians for the right-sided stimuli. These results indicate a more balanced attentional capacity in musicians, and may reflect more equal neural development and equally efficient connections between the hemispheres – possibly caused by extended musical training in childhood. In line with this, we have found, using EEG, that musicians have more bilateral neural connectivity than non-musicians. Specifically, while non-musicians exhibit the typical asymmetry in interhemispheric transfer time (faster right-to-left than left-to-right), musicians show an unusual lack of asymmetry. We are now extending this research programme to investigate lateralisation in those with computer-gaming expertise, with the use of fMRI.

  • Patston, L.L.M., Kirk, I.J., Rolfe, M.H.S., Corballis, M.C., Tippett, L.J. (2007). The unusual symmetry of musicians: Musicians have equilateral interhemispheric transfer for visual information. Neuropsychologia, 45, 2059-2065.
  • Patston, L.M., Hogg, S.L., Tippett, L.J. (2007). Attention in musicians is more bilateral than in non-musicians.  Laterality, 12, 262-272.
  • Patston, L.M., Corballis, M.C., Hogg, S.L., Tippett, L.J. (2006).  The neglect of musicians:  Line bisection reveals an opposite bias.  Psychological Science, 17, 1029-1031.


Laterality and Handedness in Twins (Corballis)

I am currently leading a research project that uses MRI to examine functional and structural asymmetries in twins. A particular focus of interest is on identical twins of opposite handedness (so-called "mirror twins"), who comprise some 22% of the population of identical twins. The question is whether they also show mirroring of various indices of cerebral asymmetry. This project is supported by a Marsden grant, and is also providing general information about the interrelations between handedness and both structural and functional asymmetries.

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Memory


Associative Encoding (Addis)

We have used a semantic-relatedness paradigm to examine the role of inferior frontal gyrus and hippocampus in associative encoding. This paradigm involves presenting triads with varying numbers of semantic relations during encoding. Triads with fewer associations have higher generative load, whereas triads with more associations had higher relational load. We found that hippocampal activity was modulated by the relational load of the encoding task while the left inferior frontal activity was modulated by generative load. We have also used this paradigm to examine whether age-related declines in relational encoding reflect dysfunction of inferior frontal gyrus linked with deficient generation of associations, and/or hippocampal dysfunction linked with impoverished binding of associations.

  • Addis, D.R., McAndrews, M. P. (2006). Prefrontal and hippocampal contributions to the generation and binding of semantic associations during successful encoding. NeuroImage, 33, 1194-1206.


Autobiographical Memory (Addis)

One line of my research seeks to understand the neural network supporting autobiographical memory retrieval. Focussing on the role of the hippocampus within this neural network, we have found that autobiographical memories with higher levels of detail, emotionality and personal significance were associated with greater hippocampal activity, even when other attributes, such as recency, were taken into account. We have also examined the neural bases of specific (unique) and general (repeated) autobiographical memories. Using functional connectivity analyses (spatiotemporal partial least squares), we identified distinct sub-networks supporting these autobiographical memory types. In collaboration with Dr Elizabeth Kensinger (Boston College) and Dr Kelly Giovanello (University of North Carolina Chapel Hill), we are further investigating the neural bases of specific and general autobiographical memories.

  • Addis, D.R., McIntosh, A.R., Moscovitch, M., Crawley, A.P., McAndrews, M.P. (2004). Characterizing the spatial and temporal features of autobiographical memory retrieval networks: A partial least squares approach. NeuroImage, 23, 1460-1471.
  • Addis, D.R., Moscovitch, M., Crawley, A.P., McAndrews, M.P. (2004). Recollective qualities modulate hippocampal activation during autobiographical memory retrieval. Hippocampus, 14, 752-762.


Hippocampal Theta (Kirk)

I am interested in studying slow-wave rhythms in EEG in humans during mnemonic and general cognitive processing. It is suggested that frontal-midline theta (a human EEG rhythm) is involved in mnemonic networks, similar to the hippocampal theta rhythm studied in rats and the processing of memory and emotion.

  • Mitchell D.J., McNaughton N., Flanagan D., Kirk I.J. (2008). Frontal-midline theta from the perspective of hippocampal "theta". Progress in Neurobiology, 86,156-185.
  • Kirk, I.J., Mackay, J.C. (2003). The role of theta-range oscillations in synchronising and integrating activity in distributed mnemonic networks. Cortex, 39, 993-1008.
    Kirk IJ, Oddie SD, Konopacki J, Bland BH. (1996). Evidence for differential control of posterior-hypothalamic, supramammillary and medial mammillary theta-related cellular discharge by ascending and descending pathways. J. Neuroscience, 16, 5547-5554.
  • Kirk IJ, MCNaughton N. (1991). Supramammillary cell firing and hippocampal rhythmical slow activity. Neuroreport, 2, 723-726.


Long Term Potentiation (Kirk)

Long term potentiation (LTP) is thought to be the cellular mechanism underlying memory. LTP is most often studied in animals, or in slice preparations. LTP can be seen as an amplification in the signal transmission between cells. We have demonstrated that LTP can be non-invasively studied in healthy human subjects using EEG and fMRI. This line of research includes two major projects investigating: (1) LTP and neural plasticity in human visual and auditory cortices, with Dr Tim Teyler (Washington), Dr Idil Cavus (Yale) and Dr Jeff Hamm (funded by NIH (USA) & Neurological Foundation of NZ); and (2) the role of genetics (brain-derived neurotrophic factor v val66met polymorphism) in LTP induction and maintenance, and in mnemonic processes generally, with Dr Karen Waldie (funded by Marsden).

  • Ross R.M., McNair N.A., Fairhall S.L., Clapp W.C., Hamm J.P., Teyler T.J., Kirk I.J. (2008). Induction of orientation-specific LTP-like changes in human visual evoked potentials by rapid sensory stimulation. Brain Research Bulletin, 76, 97-101
  • Clapp W.C., Muthukumaraswamy S.D., Hamm J.P., Teyler T.J., Kirk I.J. (2006). Long-term enhanced desynchronization of the alpha rhythm following tetanic stimulation of human visual cortex. Neuroscience Letters, 398, 220-223.
  • Teyler T.J., Hamm J.P., Clapp W.C., Johnson B.W., Corballis M.C., Kirk I.J. (2005). Long-term potentiation of human visual evoked responses. European Journal of  Neuroscience, 21, 2045-2050.
  • Clapp W.C., Zaehle T., Lutz K., Marcar V., Kirk I.J., Hamm J.P., Teyler T.J., Corballis M.C., Jäncke L. (2005). Long Term Potentiation in the Human Visual Cortex: an fMRI study. Neuroreport, 16, 1977-1980.


Remember/Know Judgments (Hautus)

Tulving introduced the Remember/Know paradigm for testing recognition memory in 1985. In this paradigm an observer is presented with a list of words. Later, the observer is presented with individual words chosen from either the list they were previously shown (old words) or words from a list they have never been shown (new words). The task is to indicate whether the word presented is an 'old' or 'new' word. When the observer indicates that the word presented was an 'old' word, they must make a second judgment. Did they 'remember' the word, with a corresponding awareness of some aspect of the original presentation, or did they simply just 'know' that they had seen the word previously? Such experiments yield important information about the functioning of memory, and it is constructive to try and model the data collected in a manner that provides a level of explanation of memory processes. SDT models are turning out to provide better accounts of the data obtained in these experiments than more traditional models.

  • Hautus, M.J., Macmillan, N.A., Rotello, C.M. (2008). Toward a complete decision model of item and source recognition. Psychonomic Bulletin and Review, 15, 889-905.
  • Rotello, C M., Macmillan, N.A., Hicks, J.L., Hautus, M.J. Interpreting the effects of response bias on remember-know judgments using signal detection and threshold models. Memory & Cognition, 34, 1598-1614.
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Mental Rotation & Object Recognition


Object Identification (Hamm)

The process of identifying an object is not an "all or none" process. Theories of object identification suggest that objects are initially identified at some general level of conceptualisation with additional visual processing required to extract more specific identity information. My interests in object identification lies in attempting to understand 1) the nature of the representation that is initially contacted 2) what semantic information this representation provides and 3) what processes are included in the "additional visual processing" that is thought to be required to more specifically identify the object.

  • Wells, I., Hamm, J.P. (2009). Flanker compatibility effects and rotated object identification.  Canadian Journal of Experimental Psychology, 63, 33-9
  • Hamm JP, Johnson BW, Kirk IJ. (2002). Comparison of the N300 and N400 ERPs to picture stimuli in congruent and incongruent contexts. Clin Neurophysiol, 113, 1339-50.
  • Hamm JP, McMullen PA. (1998). Effects of orientation on the identification of rotated objects depend on the level of identity. J Exp Psychol Hum Percept Perform, 24, 413-26.


Processing of rotated shapes (Corballis/Hamm)

One of the problems of shape recognition is how people recognise shapes that have been rotated away from the upright.  Our research suggests that people extract descriptions of shapes that are independent of their orientations – for example, when rotated shapes are presented in rapid sequence, people can usually name the shapes, but cannot tell their orientations.  They appear also to be impervious to left-right sense of the shapes (e.g., whether a letter such as R is normal or backward).  Once identified, the orientation of the shape may then be determined, and only through a later process of mental rotation is its left-right sense established.  We are investigating and refining our understanding of these processes both through experimental techniques and through the use of EEG and fMRI to determine which areas in the brain are involved.

  • Milivojevic, B., Hamm, J. P., & Corballis, M. C. (2009). Functional neuroanatomy of mental rotation. Journal of Cognitive Neuroscience, 21, 945-959.
  • Hamm JP, Johnson BW, Corballis MC. (2004). One good turn deserves another: an event-related brain potential study of rotated mirror-normal letter discriminations. Neuropsychologia, 42, 810-20.
  • Muthukumaraswamy SD, Johnson BW, Hamm JP. (2003). A high density ERP comparison of mental rotation and mental size transformation. Brain and Cognition, 52, 271-80.
  • Johnson BW, McKenzie KJ, Hamm JP. (2002). Cerebral asymmetry for mental rotation: effects of response hand, handedness and gender. Neuroreport, 13, 1929-32.
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Mental Time Travel


Evolution of Mental Time Travel (Corballis)

Human beings have the ability to recall not only facts about the world (semantic memory), but also of personal episodes we have experienced in the past (episodic memory). Recent fMRI research suggests that this ability to remember the past is close linked to our ability to imagine ourselves in the future, i.e., they are both part of a more general mental time-travel faculty. Adopting a comparative evolutionary perspective, Dr Thomas Suddendorf and I have argued that this faculty is not found elsewhere in the animal kingdom, and that it played a major role in human evolution.

  • Suddendorf, T., & Corballis, M. C. (2007). The evolution of foresight: What is mental time travel, and is it unique to humans? Behavioral and Brain Sciences, 30(3), 299-313
  • Suddendorf, T., Addis, D. R., & Corballis, M. C. (2009). Mental time travel and the shaping of the human mind. Philosophical Transactions of the Royal Society of London B: Biological Sciences, 364, 1317-1324.

Remembering the Past & Imagining the Future (Addis)

In collaboration with Prof Daniel Schacter (Harvard University), we are investigating how memories of past events are used in the simulation of future personal experiences. We have proposed the constructive episodic simulation hypothesis in which we claim that the constructive character of episodic memory enables individuals to imagine future episodes, by enabling flexible extraction and recombination of elements from previous experiences. We have investigated this proposal using neuroimaging (fMRI), finding significant overlap between the regions used to remember and imagine events in a core network. Moreover, the hippocampus appears to be recruited more so when imagining scenarios.

  • Addis, D. R., Pan, L., Vu, M. A., Laiser, N., Schacter, D. L. (2009). Constructive episodic simulation of the future and the past: Distinct subsystems of a core brain network mediate imagining and remembering. Neuropsychologia, 47, 2222–2238.
  • Schacter, D. L., Addis, D. R., Buckner, R.L. (2007). The Prospective Brain: Remembering the Past to Imagine the Future. Nature Reviews Neuroscience, 8, 657-661.
  • Schacter, D. L., Addis, D. R. (2007). The cognitive neuroscience of constructive memory: Remembering the past and imagining the future. Philosophical Transactions of the Royal Society (B), 362, 773-786.
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Perception & Motor Processing


Music Perception and Processing (Hamm & Kirk)

In collaboration with Carolyn Wu, we are investigating music perception and processing in non-musicians, musicians with and without perfect/absolute pitch and people with amusia who have the inability to recognize melodies. 

  • Wu, C.C., Kirk, I.J., Hamm, J.P., & Lim, V.K. (2008). The neural networks involved in pitch labeling of absolute pitch musicians. Neuroreport, 19, 851-854.
  • Altenmuller, E., Schurmann, K,  Lim, V.K., & Parlitz, D . (2002). Hits to the left,- flops to the right: Different emotions during listening to music are reflected in cortical lateralisation patterns.  Neuropsychologia, 40, 2242-2256.
  • Lim, V. K., Lambert, A., & Hamm, J.P (2001).  A paradox in the laterality of melody processing.  Laterality, 4, 369-380.

Perceptual and Motor Processes: Braille Reading and the Blind (Hughes)

My research interests are primarily directed to understanding the linkages between perception, cognition and motor control, particularly in the case of manual activity, and even more particularly in the case of the blind. Specifically, my research focuses on (1) texture perception by touch and (2) the complex interactions between perception, cognition and motor control in Braille reading. I have worked with blind people for many years and have acquired knowledge of the issues that impact the lives of the visually impaired.

  • Hughes, B, AWA Van Gemmert & GE Stelmach (2008). 'What finger movements reveal about Braille reading processes'. In Proceedings of European Conference on Visual Perception, Utrecht, Netherlands.
  • Hughes, B, & AWA Van Gemmert (2008). 'Perceptual-motor control and language processing contributions to Braille reading velocity.'  In Proceedings of the 20th Annual Convention of the Association for Psychological Science, Chicago IL.
  • Hughes, B, AWA Van Gemmert & GE Stelmach (2008). 'Texture meets text: On the kinematics of Braille reading.'  In Proceedings of the 16th Symposium on Haptic Interfaces for Virtual Environments and Teleoperator Systems. IEEE Publications.
  • Hughes, B (2007). 'Proximal stimulation, objects of perception and the blind'.  Commentary on HC Dijkerman and EHF de Haan, Somatosensory processes subserving perception and action. Behavioral and Brain Sciences, 30, 212-213.


Plasticity in the Auditory System (Purdy)

In collaboration with Dr Lim, Dr Munro (University of Manchester) and Dr Hall (Nottingham), we are using fMRI and acoustic reflexes to investigate the changes in the auditory system after unilateral deprivation to normal hearing individuals.

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Psychophysics


Segregation and Localization of Objects by the Auditory System (Hautus)

Recent research in collaboration with Dr Blake Johnson has indicated that a certain type of Dichotic Pitch (there are many types) provides unique electrophysiological indicators to binaural auditory processing. Indeed, the only cue to the presence of a separate auditory object (the pitch) stems from interaural timing differences. No other monaural or binaural cues are required to generate this percept. Our research has utilized high-density electroencephalography to help determine the sequences of processing stages for these stimuli. The EEG laboratory is adjacent to the psychophysics laboratory, which enables an efficient and productive synergy between these two areas.

  • Hautus, M. J., Johnson, B. W., Colling, L. J. (2009). Event-related potentials for interaural time differences and spectral cues. Neuroreport, 20, 951-956.
  • Clapp WC, Johnson BW, Hautus MJ. (2007). Graded cue information in dichotic pitch: effects on event-related potentials. Neuroreport, 18, 365-368.
  • Hautus, M. J., Johnson, B. W. (2005). Object-related brain potentials associated with the perceptual segregation of a dichotically-embedded pitch. Journal of the Acoustical Society of America, 116, 275-280.

Modelling of Performance in Sensory Tasks (Hautus)

When an assessment of sensory (or other) performance is undertaken, the most desirable outcome would be to produce a measure of performance that is independent of both the task and the response bias of the individual. Signal Detection Theory (SDT) presents an approach to accomplish this by specifying separate measures of response bias and performance. In theory (but not quite in practice) SDT will provide the same estimate of performance for the same stimuli judged in different tasks. This is certainly not true of commonly used methods of performance, such as the proportion of correct judgements. My research has involved developing and evaluating SDT-based models for tasks such as the same-different task and the matching-to-sample task. I am currently developing models for tasks commonly employed in the field of sensory evaluation.

  • Hautus, M.J., Lee, A.J. (2006). Estimating sensitivity and bias in a yes/no task.' British Journal of Mathematical & Statistical Psychology, 59, 257-273.
  • Hautus, M.J., Collins, S. (2003). An assessment of response bias for the same-different task: Implications for the single-interval task. Perception & Psychophysics, 65, 844-860.
  • Hautus, M.J., Meng, X. (2001). Decision strategies in the ABX (matching-to-sample) psychophysical task. Perception & Psychophysics, 64, 89-106.


Auditory Psychophysics (Hautus)

An ongoing debate in auditory psychophysics relates to which characteristic of the magnitude of an auditory stimulus the auditory system is most attuned to: amplitude or intensity. Dr Daniel Shepherd, of AUT University, and I are currently undertaking some auditory psychophysical experiments, collecting psychometric functions for pedestal levels around absolute threshold. The findings may bring further clarity to this issue because there is a predictable relationship between the negative masking function and the pedestal effect. This relationship differs whether amplitude or intensity is employed. The psychometric functions should yield the empirical relationship, which will then be compared with the predictions.

  • Shepherd, D., Hautus, M.J., Hutchinson, H. (2008). Psychometric functions for hybrid difference discrimination/increment detection tasks. Journal of the Acoustic Society of America, 124, EL302-307.
  • Shepherd, D., Hautus, M.J. (2009). Negative masking and the units problem in audition. Hearing Research, 247, 60-70.
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