Age effects in coding tasks: Componential analysis and test of the sensory deficit hypothesis.

Abstract

Multiple forms of a symbol-digit substitution task were used to provide a componential analysis of age differences in coding task performance. The results demonstrated age differences in feature encoding, memory, and visual search. A 2nd experiment was conducted with young adults to investigate a sensory deficit as a locus of age differences. The spatial contrast sensitivity deficit of older adults was simulated on forms by applying a digital filter. Persons in the age-simulated contrast condition performed worse than those in the normal contrast condition. The stimulus degradation effect was linked to visual search speed. The study illustrates the utility of componential analysis and offers direct support for the hypothesis that sensory deficits affect performance on tasks used to assess intelligence.

Fluid intelligence is independently associated with all-cause mortality over 17 years in an elderly community sample: An investigation of potential mechanisms

“…Since reaction time was controlled for, the aspects of SLMT that are associated with mortality would appear to be a combination of processing speed with memory and attention performance. Further research into which constituents of the SLMT task best predict mortality could adapt the frameworks used by Gilmore et al (2006) and Salthouse and Kersten (1993) to modify the SLMT task into components that separately measure the processing speed, memory and attentional aspects of the task.…”

“…Only a self-reported measure of vision impairment was included in the baseline interview, which may not accurately reflect visual functioning. Sensory function, particularly visual acuity, can influence performance on tasks like SLMT (Gilmore et al, 2006). Self-report measures of health status (disease history, functional ability) may also have been inaccurate, although objective health measures (grip strength, reaction time) were also included as predictors in the models.…”

“…There was a strong independent effect of SLMT even after adjusting for the hypothesized mechanisms of the relationship together with reaction time and sensory impairment. In addition to mental speed, SLMT measures the efficiency of visual search and memory for the symbols presented in the task (Gilmore et al, 2006). Since reaction time was controlled for, the aspects of SLMT that are associated with mortality would appear to be a combination of processing speed with memory and attention performance.…”

“…The Symbol-Letter Modalities Test (SLMT), a task similar to Smith's (1973) Symbol-Digit Modalities Test and Wechsler's (Wechsler, 1981) DigitSymbol Substitution, is a perceptual speed test that provides a measure of fluid intelligence. SLMT measures the efficiency of visual search and memory for the symbols presented in the task (Gilmore, Spinks, & Thomas, 2006) and performance on the task is correlated with measures of general intelligence such as the Wechsler Adult Intelligence Scale (Waldmann, Dickson, Monahan, & Kazelskis, 1992). The National Adult Reading Test (NART; Nelson, 1982) is a test of vocabulary that provides a measure of crystallized intelligence.…”

Vision and intelligence at age 83 in the Lothian Birth Cohort 1921

“…One way to test this more directly is to manipulate the quality of the visual information system-as can be achieved by degrading the stimuli-and investigate its influence on specifically visual cognitive tasks. This approach was used by Gilmore, Spinks, and Thomas (2006), where they manipulated the stimuli in the symbol-digit substitution task by applying a digital filter to simulate the contrast sensitivity deficits of older people. This manipulation lowered performance on the task by slowing visual search speed.…”