Sabine Heuer

A new eye -tracking method to assess attention allocation in individuals with and without aphasia using a dual-task paradigm

UNLABELLED Numerous authors report that people with aphasia have greater difficulty allocating attention than people without neurological disorders. Studying how attention deficits contribute to language deficits is important. However, existing methods for indexing attention allocation in people with aphasia pose serious methodological challenges. Eye-tracking methods have great potential to address such challenges. We developed and assessed the validity of a new dual-task method incorporating eye tracking to assess attention allocation. Twenty-six adults with aphasia and 33 control participants completed auditory sentence comprehension and visual search tasks. To test whether the new method validly indexes well-documented patterns in attention allocation, demands were manipulated by varying task complexity in single- and dual-task conditions. Differences in attention allocation were indexed via eye-tracking measures. For all participants significant increases in attention allocation demands were observed from single- to dual-task conditions and from simple to complex stimuli. Individuals with aphasia had greater difficulty allocating attention with greater task demands. Relationships between eye-tracking indices of comprehension during single and dual tasks and standardized testing were examined. Results support the validity of the novel eye-tracking method for assessing attention allocation in people with and without aphasia. Clinical and research implications are discussed. LEARNING OUTCOMES Readers will be able to: (1) summarize the nature of dual-task paradigms, (2) identify shortcomings of existing dual-task measures of attention allocation for application to people with aphasia, (3) describe how eye-tracking measures may be recorded and analyzed to reflect differences in attention allocation across conditions, and (4) summarize potential clinical applications for eye-tracking measures of attention allocation.

The influence of image characteristics on image recognition: a comparison of photographs and line drawings

Background: Photographs provide more information including colour, luminance, texture, and shading cues compared to line drawings. There is evidence that these additional cues facilitate image recognition in individuals with and without neurological deficits. Black-and-white line drawings and colour photographs are commonly used with individuals with aphasia in evaluation and treatment. Eye tracking provides an opportunity to assess the influence of these different image types on object recognition processes without relying on verbal responses. Aims: The purpose of this study was to determine whether differences in object recognition of photographs and line drawings were observed using eye-tracking measures. Specific goals were to compare the influence of (a) image type of the same target image presented as colour photograph and black-and-white line drawing and (b) degree of colour diagnosticity (high-colour diagnostic natural objects and low-colour diagnostic human-made objects) in multiple-choice image displays on language-mediated eye movements in language-normal adults. Methods & Procedures: Eye movements of 19 participants were recorded while they viewed 66 multiple-choice image displays of colour photographs and black-and-white line drawings presented with a verbal stimulus. Target images included high-colour diagnostic natural objects and low-colour diagnostic human-made objects. Outcomes & Results: Participants allocated significantly greater proportions of fixation duration and first-pass gaze duration to the photographs compared to line drawings. No significant differences were observed for colour diagnosticity differences within the colour or the black-and-white line drawing displays. Conclusions: Eye tracking indexed significant differences in fixation duration allocated to target images in displays that only differed with respect to image type and colour, and were otherwise carefully controlled for shape, size, orientation, and content conveyed. Results suggest that language-normal participants’ object recognition was facilitated by colour photographs compared to line drawings, highlighting the clinical relevance and the need for research of image design for clinical use with individuals with neurological impairments.

More than the Verbal Stimulus Matters: Visual Attention in Language Assessment for People with Aphasia Using Multiple-Choice Image Displays.

Purpose Language comprehension in people with aphasia (PWA) is frequently evaluated using multiple-choice displays: PWA are asked to choose the image that best corresponds to the verbal stimulus in a display. When a nontarget image is selected, comprehension failure is assumed. However, stimulus-driven factors unrelated to linguistic comprehension may influence performance. In this study we explore the influence of physical image characteristics of multiple-choice image displays on visual attention allocation by PWA. Method Eye fixations of 41 PWA were recorded while they viewed 40 multiple-choice image sets presented with and without verbal stimuli. Within each display, 3 images (majority images) were the same and 1 (singleton image) differed in terms of 1 image characteristic. The mean proportion of fixation duration (PFD) allocated across majority images was compared against the PFD allocated to singleton images. Results PWA allocated significantly greater PFD to the singleton than to the majority images in both nonverbal and verbal conditions. Those with greater severity of comprehension deficits allocated greater PFD to nontarget singleton images in the verbal condition. Conclusion When using tasks that rely on multiple-choice displays and verbal stimuli, one cannot assume that verbal stimuli will override the effect of visual-stimulus characteristics.

Prognostic variables for successful lexical retrieval of treated and untreated verbs vary greatly suggesting that different cognitive processes might underlie the production of treated and untreated verbs

This review provides a summary and appraisal commentary on the treatment review by de Aguiar, V., Bastiaanse, R., & Miceli, G. (2016). Improving production of treated and untreated verbs in aphasia: A meta-analysis. Frontiers in Human Neuroscience, 10:468. doi: 10.3389/fnhum.2016.00468 Source of funding and declaration of interests: Funding was provided by the Provincia Autonoma di Trento and Fondazione CaRiTRO and Erasmus Mundus Joint Doctorate IDEALAB. No conflicts of interests were declared.

Development of an eye-tracking method to assess mental set switching in people with aphasia

ABSTRACT Background: Deficits in cognitive flexibility contribute to impaired functional communication in people with aphasia. Understanding the relationship between functional communication and cognitive flexibility in people with neurologic communication disorders is important. However, traditional methods to assess mental set switching pose significant linguistic, cognitive and motoric response confounds. Eye-tracking methods have great potential to address these challenges. Aims: The goal of this study was to develop and validate an eye-tracking method to index mental set switching in individuals without neurological impairment based upon performance on a nonlinguistic switching task. Methods: Eye movements of 20 adults without communication disorders were recorded as they completed a switching task, requiring participants to match stimuli to one or two search criteria (colour or shape) in single- and mixed-task conditions. Differences between single and mixed conditions were assessed with eye-tracking measures. Performance on the eye-tracking task was compared to standardized measures of cognitive flexibility. Results: Eye-tracking measures indexed significant differences between nonswitch and switch trials within and between single- and mixed-task condition. Some standardized assessment measures correlated significantly with the eye movement measures. Conclusions: Results support the construct validity of the novel eye-tracking method for assessing cognitive switching in language-normal adults. Clinical and research implications are discussed.