Current Research Projects

Monitoring and control in language production

What situations lead to an increased need for control in language production?

We have demonstrated that not only semantic overlap, but also overlap in segments (phonemes in spoken production and graphemes in written production) can create interference and an increased need for control. We are currently investigating:

1. The locus of this effect (using EEG)
2. The influence of deficit type (semantic vs. phonological) on modulating this interference

How do people repair the errors they make in language production?

We are interested in understanding whether repairing an error entails conscious understanding of the nature of the error, or whether repairs arise from unconscious mechanisms which, in turn, trigger conscious awareness of errors. We are currently investigating:

1. Whether error detection in speech is affected by how likely errors are
2. Whether people are aware of the corrections they make in typing

How domain-general are the mechanisms behind monitoring and error detection in language production?

We are investigating whether detecting language errors shows the same EEG indices as have been reported in action monitoring.

Selection mechanisms in language production

Is lexical selection competitive or not?

We have suggested a new perspective on competitive vs. competitive selection, by proposing the superimposition of a decision-making framework with a flexible criterion on the information derived from models that capture the internal dynamics of language production (Nozari & Hepner, 2018, 2019). Current investigations focus on:

1. Fitting models to data to test the hypotheses derived from the theoretical framework
2. Determining how often and under what circumstances the criterion changes

Is criterion setting in language production affected by drain damage?

The above framework suggests that producing a word has a decision component, which might be independently affected by brain damage. We are investigating:

1. Whether a stroke can cause an inability to shift the criterion flexibly based on task demands
2. What lesions are associated with this problem

Role of inhibitory control in language production

Is inhibitory control involved in word production?

We have demonstrated the separation of activation and inhibition deficits in stroke survivors with word production deficits (Nozari, 2019). We are now interested in understanding which types of inhibitory control are important for which linguistic operations (lexical selection, phonological encoding, etc.).

Is inhibitory control involved in sentence production?

This is an NSF-funded project investigating the role of inhibitory control in subject-verb agreement.

Is inhibitory control involved in conversation-level production?

We have begun to use the activation/inhibition distinction in word production deficits to predict differences in conversation-level behaviors, such as perspective taking and incorporating referential context into communication.

A model of writing/typing

We are working on refining a computational model of writing/typing that accurately captures the pattern of performance in neurotypical adults and individuals with brain damage. Specific challenges we are working on include:

1. Solving the problem of non-adjacent repeated letters
2. Accurate representation of adjacent repeated letters (geminates)
3. Simultaneous capture of all types of graphemic buffer/orthographic working memory errors and their relative frequencies

Children’s language production system

Are the dynamics of word production similar between adults and children?

We have previously shown that computational models of word production can be used to model children’s picture naming, auditory repetition, and monitoring behavior (Budd, Hanley, & Nozari, 2012; Hanley, Cortis, Budd, & Nozari, 2016). We are now investigating more nuanced features such as interactivity and cascading in children’s production system.

Are the dynamics of syntactic encoding similar between adults and children?

We are investigating whether the processes underlying the production of noun-verb agreement fundamentally the same or different in adults and children.