Department of Psychology
RCCN basic research
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.
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.
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.
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.
