Measuring the Difficulty Watching Video With Hemianopia and an Initial Test of a Rehabilitation Approach

Further evaluation of narrative description as a measure of cognitive function in Alzheimer's disease

OBJECTIVE

The narrative description (ND) test objectively measures the ability to understand and describe visual scenes. As subtle differences in speech occur early in cognitive decline, we analyzed linguistic features for their utility in detecting cognitive impairment and predicting downstream decline.

METHOD

Participants (n = 52) with normal cognition to mild dementia performed the ND test (watched twenty 30-s video clips and described the visual content). Cognitive function was followed for up to 5 years. We computed simple linguistic features such as content efficiency, speech rate, and part of speech and unique word counts. We examined (a) relationships between cognitive status and ND score and linguistic features; (b) ability to discriminate early cognitive impairment from normal cognition using ND score and linguistic features; and (c) whether ND score and linguistic features were associated with future cognitive functional decline.

RESULTS

Many of the linguistic-feature metrics were related to cognitive status. Many of the linguistic features could distinguish between the cognitively normal group and the mild cognitive impairment (MCI) and Dementia groups. The area under the curve (AUC) for ND score alone was 0.74, with a nonsignificant increase to 0.78 when adding mean word length. Among participants with subjective cognitive decline (SCD) at the first visit, a smaller number of words plus more interjections or a lower ND score at baseline were predictive of future cognitive decline.

CONCLUSIONS

While many linguistic features were associated with cognitive status, and some were able to detect early cognitive impairment or predictive of future cognitive decline, all the features we tested seem to have been captured by the ND score. Thus, adding linguistic measures to the ND test score did not add to its value in assessing current or predicting future cognitive status. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

The Effect of Zoom Magnification and Large Display on Video Comprehension in Individuals With Central Vision Loss

Purpose

A larger display at the same viewing distance provides relative-size magnification for individuals with central vision loss (CVL). However, the resulting large visible area of the display is expected to result in more head rotation, which may cause discomfort. We created a zoom magnification technique that placed the center of interest (COI) in the center of the display to reduce the need for head rotation.

Methods

In a 2 × 2 within-subject study design, 23 participants with CVL viewed video clips from 1.5 m (4.9 feet) shown with or without zoom magnification, and with a large (208 cm/82" diagonal, 69°) or a typical (84 cm/33", 31°) screen. Head position was tracked and a custom questionnaire was used to measure discomfort.

Results

Video comprehension was better with the large screen (P < 0.001) and slightly worse with zoom magnification (P = 0.03). Oddly, head movements did not vary with screen size (P = 0.63), yet were greater with zoom magnification (P = 0.001). This finding was unexpected, because the COI remains in the center with zoom magnification, but moves widely with a large screen and no magnification.

Conclusions

This initial attempt to implement the zoom magnification method had flaws that may have decreased its effectiveness. In the future, we propose alternative implementations for zoom magnification, such as variable magnification.

Translational Relevance

We present the first explicit demonstration that relative-size magnification improves the video comprehension of people with CVL when viewing video.

An implementation of Bubble Magnification did not improve the video comprehension of individuals with central vision loss

PURPOSE

People with central vision loss (CVL) watch television, videos and movies, but often report difficulty and have reduced video comprehension. An approach to assist viewing videos is electronic magnification of the video itself, such as Bubble Magnification.

METHODS

We created a Bubble Magnification technique that displayed a magnified segment around the centre of interest (COI) as determined by the gaze of participants with normal vision. The 15 participants with CVL viewed video clips shown with 2× and 3× Bubble Magnification, and unedited. We measured video comprehension and gaze coherence.

RESULTS

Video comprehension was significantly worse with both 2× (p = 0.01) and 3× Bubble Magnification (p < 0.001) than the unedited video. There was no difference in gaze coherence across conditions (p ≥ 0.58). This was unexpected because we expected a benefit in both video comprehension and gaze coherence. This initial attempt to implement the Bubble Magnification method had flaws that probably reduced its effectiveness.

CONCLUSIONS

In the future, we propose alternative implementations of Bubble Magnification, such as variable magnification and bubble size. This study is a first step in the development of an intelligent-magnification approach to providing a vision rehabilitation aid to assist people with CVL.

Narrative video scene description task discriminates between levels of cognitive impairment in Alzheimer's disease

The process of interpreting and acting upon the visual environment requires both intact cognitive and visual systems. The narrative description (ND) task, initially developed to detect changes in ecologically relevant visual function in people with impaired vision, is an objective measure of the ability to perceive, understand, and describe a visual scene in a movie clip.

OBJECTIVE

Because the ND task draws heavily on semantic and working memory ability in addition to basic visual perception, we aimed to assess the discriminative performance of this task across levels of cognitive impairment.

METHOD

We recruited 56 participants with cognitive status ranging from normal cognition to mild dementia (median age 82, range 66 to 99 years) to watch 20 30-s video clips and describe the visual content without time constraints. These verbal responses were transcribed and processed to generate ND shared word scores using a "wisdom of the crowd," natural-language processing approach. We compared ND scores across diagnostic groups, and used linear mixed models to examine decrements in task performance.

RESULTS

There was a stepwise decline of ND scores with increasing levels of cognitive impairment. Additional analyses showed that ND performance was highly related to performance on the Montreal Cognitive Assessment (MoCA) and domain-specific neuropsychological tests for semantic fluency and set shifting. Other models demonstrated differences in ND performance related video content between cognitively normal and impaired participants.

CONCLUSION

The ND test was able to detect decrements in task performance between levels of cognitive impairment and was related to other global neuropsychological measures. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

People With Central Vision Loss Have Difficulty Watching Videos

Purpose

People with central vision loss (CVL) often report difficulties watching video. We objectively evaluated the ability to follow the story (using the information acquisition method).

Methods

Subjects with CVL (n = 23) or normal vision (NV, n = 60) described the content of 30-second video clips from movies and documentaries. We derived an objective information acquisition (IA) score for each response using natural-language processing. To test whether the impact of CVL was simply due to reduced resolution, another group of NV subjects (n = 15) described video clips with defocus blur that reduced visual acuity to 20/50 to 20/800. Mixed models included random effects correcting for differences between subjects and between the clips, with age, gender, cognitive status, and education as covariates.

Results

Compared to both NV groups, IA scores were worse for the CVL group (P < 0.001). IA reduced with worsening visual acuity (P < 0.001), and the reduction with worsening visual acuity was greater for the CVL group than the NV-defocus group (P = 0.01), which was seen as a greater discrepancy at worse levels of visual acuity.

Conclusions

The IA method was able to detect difficulties in following the story experienced by people with CVL. Defocus blur failed to recreate the CVL experience. IA is likely to be useful for evaluations of the effects of vision rehabilitation.