The Older Adults' Iconic Memory Decay And Its Diagnosis

With the society aging problem becoming more and more serious,researches focusing on health of elder adults attract more and more attentions.People's experiences and knowledge are increasing with the age growing,but their cognitive capacities are changing to bad,especially the memory ability.Many aging diseases are relative to memory defaults,such as Alzheimer disease.Until now most studies about memory aging concentrate on the short-term memory and long term memory,but there are few about the iconic memory which is viewed as the first step of information registration in human brain.The traditional iconic memory researching paradigm met great difficulties when it was used into the elder adults.We improved the paradigm with a longer stimuli show time and lower identify difficulties,which made it well used into the elder people,and embodied their iconic memory abilities very well.With the improved paradigm,we tried to explore the reasons why elder adults' iconic memory declines by comparing the iconic memory capacity between young and elder adults.What's more,we used the discriminant analysis to classify these two groups of people's performance on iconic memory to diagnosis its aging process.40 young and 31 elder adults participated into this test.We adopted the partial-report task to test the young and elder adults' iconic memory ability.In the task,there are three kinds of target-cue onset asynchrony time to test the visual identification,iconic memory,and short-term memory separately.With the independent t-test,we got the results that elder adults' visual identification,iconic memory,and short-term memory are all worse than the young adults' significantly.From the stimuli sensory to their primary processing in human brain,the whole process is continuous.So to test the difference in iconic memory and short-term memory,we brought in the covariance analysis to diminish the effect of visual identification factor.The result showed that there are still significant differences between young and elder adults in the iconic and short-term memory.So we got the conclusion that even the iconic memory and short-term memory are high relevant to visual identification,the iconic memory and short-term memory aging still exists.And they may be caused by the processing speed decline or difficulties in memory recalling.After we ensured the differences between young and elder adults in the partial-report task,we try to use the discrimiant analysis to build a discriminant criterion to classify different groups of people's performance on iconic memory.The kernel-based nonparametric discriminant method got the lowest error rate,after comparing with the Fisher and Bayes discriminant method.So we think that the nonparametric discriminant method adjusts the iconic memory model very well.In this study we improved the partial-report task to test the iconic memory decay in older adults,and found a proper discriminate method to diagnosis this decay.All the work will be a reference for the diagnosis of cognitive aging,even the non-normal aging in future.