Effects of healthy ageing on precision and binding of object location in visual short term memory.

Yoni Pertzov,Maike Heider,Masud Husain,Yuying Liang

doi:10.1037/a0038396

Abstract

Visual short term memory (STM) declines as people get older, but the nature of this deterioration is not well understood. We tested 139 healthy subjects (19–83 years) who were first required to identify a previously seen object and then report its location using a touchscreen. Results demonstrated an age-related decline in both object identification and localization. Deterioration in localization performance was apparent even when only 1 item had to be remembered, worsening disproportionately with increasing memory load. Thus, age-dependent memory degradation cannot be explained simply by a decrease in the number of items that can be held in visual STM but rather by the precision with which they are recalled. More important, there was no evidence for a significant decrease in object-location binding with increasing age. Thus, although precision for object identity and location declines with age, the ability to associate object identity to its location seems to remain unimpaired. As it has been reported that binding deficits in STM might be the first cognitive signs of early Alzheimer’s disease (AD), the finding that object-location binding processes are relatively intact with normal aging supports the possible suitability of using misbinding as an index measures for probing early diagnosis of AD.

Highlights

Visual short term memory (STM) declines as people get older, but the nature of this deterioration is not well understood
As it has been reported that binding deficits in STM might be the first cognitive signs of early Alzheimer’s disease (AD), the finding that object-location binding processes are relatively intact with normal aging supports the possible suitability of using misbinding as an index measures for probing early diagnosis of AD
It has been claimed that, in contrast, the ability to bind features in visual STM does not decline with aging, making such tasks potentially very useful for early screening of AD (Della Sala, Parra, Fabi, Luzzi, & Abrahams, 2012; Parra et al, 2009, 2010)

Summary

Introduction

Visual short term memory (STM) declines as people get older, but the nature of this deterioration is not well understood. While some previous studies have shown that binding of visual features remains unimpaired in healthy elderly people (Brockmole, Parra, Della Sala, & Logie, 2008; Parra, Abrahams, Logie, & Della Sala, 2009), a recent Web-based study of more than 55,000 participants reported a significant (but weak) age-related impairment in binding shape and color, in addition to a strong decline in the precision of single-feature memory (Brockmole & Logie, 2013) Another investigation using a dual-feature recall STM task (Peich, Husain, & Bays, 2013) found a decline in precision for single features as well as within-object binding impairments in elderly people when asked to reproduce from memory both the color and orientation of a colored bar. These investigations reported that binding of objects to locations is fragile (Pertzov, Dong, Peich, & Husain, 2012) and impaired in patients with focal damage to their medial temporal lobes, MTLs (Pertzov et al, 2013)

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Discussion

Conclusion