Perception, Attention, and Consciousness
The research on perception and attention focuses on change detection, temporal dynamics of attention, attention & awareness, meditation. Change detection has been studied with color, shape, illumination, real scenes, hierarchical stimuli and motion. Research on temporal dynamics of attention has focused on the role of object-based information. Research on perceptual organization has focused on figure-ground organization. Studies based on structure from motion with different color backgrounds and foregrounds support theories of figure-ground organization that stress interaction between visual pathways.
We are also exploring the link between attention and awareness. Studies with color afterimages show that types of attention do matter for awareness. We have also investigated differences between focused and distributed attention using neural measures, mainly CDA that is dependent on control of access to working memory.
We have also performed studies on meditation. An initial study was performed with sudharshan kriya yoga (SKY), which has shown enhanced preattentive processes as indexed by larger mismatch negativity amplitudes. We have also investigated changes in attentional processes with meditation practice with children who meditate and results show improved alerting and conflict effects with experience using the Attentional Network Task. We have developed a model of attention, consciousness and meditation based on the concept of adaptive workspace and currently simulations based on the model are in progress.
Affect and Cognition
Most of the studies have focused on the interaction between attention and emotion. Studies have used many paradigms including visual search, load, dwell time, hierarchical stimulus processing. Attentional dwell time studies with different emotions have shown an advantage for happy faces at short SOAs (less than 200 ms). Emotional face recognition memory presented at the background as participants performed a letter task (low load or high load) found better performance with happy faces than sad faces. Sad faces interfered with the letter task more than happy faces especially with the high load task. Happy faces are linked to global processing and sad faces to local processing. These results are interpreted with a theoretical position emphasizing the link between happy face and distributed attention and sad face and focused attention.
Studies have also shown that spatial frequency processing plays a critical role in identification of sad and happy faces. We have also found laterality effects in the identification of emotions interacting with spatial frequency information. Attentional capture (measured by inhibition of return) is affected by emotional information, hemispheric asymmetries and the nature of attention (object-based vs space-based).
The overall goal of our research aims at exploring behavioural and neural aspects of language processing in its various manifestations. In our studies on probabilistic and incremental nature of spoken sentence processing, we are interested in how certain grammatical units trigger attention shifts that indicate subtle aspects of sentence processing. We are exploring the competition between semantic vs phonological and other conceptual information in providing cues for lexical access in a probabilistic manner. We are exploring the nature of visual attention during conceptualizing and planning states of sentence production. We are investigating the effect of literacy on spoken word/sentence processing as well as speed of lexical retrieval. In this connection, we are carrying out eye tracking experiments with illiterates and semi illiterates. Our studies on bilingualism and cognitive control focus on language switching in Hindi-English bilinguals and role of language proficiency in cognitive control in bilinguals. Cognitive advantage in bilingualism could be a language specific mechanism and may or may not transfer as a general cognitive advantage.
We have been working on typical and atypical development of brain and cognition. We have reported detrimental effects of stunting due to chronic protein energy malnutrition on the development of cognitive functions in children. We have also found nonlinear, heterogeneous nature of development of cognitive functions. Our studies on the development of attentional processes like task switching, error monitoring and attentional networks in normal children as well as those with ADHD have shown that 6-9 years of age is an active period for the development of cognitive control functions for normal children but not for children with ADHD. We are currently working on the development of attentional modulation of emotions in children and adolescents.
We are working on developmental disorders like dyslexia and Attention deficit hyperactivity disorder. We have developed a battery of tests in Hindi and English language for the identification of dyslexia and are currently standardizing the battery. We are looking at the issues related to biliteracy in dyslexia in Hindi and English language. We are also looking at the interaction between auditory processing and auditory attention deficits in dyslexia. We have done a preliminary ERP study on the neuro-cognitive mechanisms of remediation in dyslexia and we found electrophysiological changes after remediation in early as well as late stages of processing. We have also conducted experiments on Attention deficit hyperactivity disorder (ADHD). We have identified the cognitive markers like error monitoring, task switching, response inhibition and delay aversion as diagnostic markers of attention deficit hyperactivity disorder.
In this research we aim to investigate the decision making under uncertainty and the effect of various factors such as emotions, social context and motivation on decision utility and outcome utility. In one of the current studies we plan to investigate the effect on experience of regret/ rejoice and subsequent choice by manipulating the current emotional state of the subject. Laterality effects with a task involving the ultimatum game has been performed which indicate that emotions affect decision making and this effect shows different asymmetries in brain depending on the visual field in which stimuli were presented.
Recently, we have also started to explore how attention interacts with Decision Making and the amount of information used in making decisions.
Learning and Memory
In this research, we are investigating how humans acquire and perform sequential and categorization skills. In the sequential skill learning experiment, we would like to formalize a theory related to chunking and working memory by independently varying the short-range and long-range memory loads. In the category learning project, we are examining the effects of local and global features of stimuli during unimodal and crossmodal category learning.