Wisdom and knowledge, cognitive functions that surely depend on being able to access and use memory, grow into old age. Yet, the literature on memory shows that intentional, episodic memory declines with age. How are we to account for this paradox? To do so, we need to understand three aspects of memory differences associated with aging, two of which have received extensive investigation: age differences in memory encoding and in retrieval. A third aspect, differences in the contents of memory representations, has received relatively little empirical attention. Here, we argue that this aspect is central to a full understanding of age differences in memory and memory-related cognitive functions. We propose that, relative to younger adults, healthy older adults (typically between 60 and 85 years of age) process and store too much information, the result of reductions in cognitive control or inhibitory mechanisms. When efficient, these mechanisms enable a focus on target or goal-relevant information to the exclusion (or suppression) of irrelevant information. Due to poor control (or reduced efficiency), the mnemonic representations of older adults can include: (i) recently activated but no-longer-relevant information; (ii) task-unrelated thoughts and/or prior knowledge elicited by the target information; and/or (iii) task-irrelevant information cued by the immediate environment. This information is then automatically bound together with target information, creating cluttered memory representations that contain more information than do those of younger adults.
It's like trying to find something in a cluttered, disorganized attic. Not only is it hard to locate what you're looking for, you get distracted by the other things you run across. "Wow, it's been years since I've seen this! I didn't even know this was up here!.... wait, what am looking for?"
I've noticed this exact problem in the kitchen. I'm the chief cook in our family, and I love to make complex dinners with lots of ingredients. I've found that unless I want to make a dozen trips to the fridge or cabinets to retrieve three items, I need to focus on one thing at a time. Get a green pepper from the vegetable crisper. Find the bottle of cooking sherry. Go get the bottle of tabasco sauce from the table. If I try to keep all three in my mind at once, I'm sure to return to the stove and think, "Okay, what the hell do I need, again?"
I wonder if this mental clutter is at the heart of my struggle with memorizing the hiragana characters in Japanese. I've done at least a cursory study of about a dozen languages -- I'm truly fluent in only a couple, but my master's degree in historical linguistics required me to learn at least the rudiments of the languages whose history I was studying. Could my difficulty in connecting the Japanese characters to the syllables they represent be because my Language Module is clogged with Old Norse and Welsh and Scottish Gaelic and Icelandic, and those all get in the way?
In any case, it's kind of a relief that I'm (probably) not suffering from early dementia. It also gives me an excuse the next time my wife gets annoyed at me for forgetting something. "I'm sorry, dear," I'll say. "I'd have remembered it, but my brain is full. But at least I remembered that the character yo looks like a yo-yo hanging from someone's finger!"
Nah, I doubt that'll work, and the fact that I remembered one of the Japanese characters instead of stopping by the store to pick up milk and eggs will only make it worse. When I want to be sure not to forget something, I guess I'll have to keep making a list.
The only problem is then, I need to remember where I put the list.