Wednesday 31 December 2014

Human Bias - Memory

Of all the different types of bias, we may be more aware of how fickle and biased our memory can be than any other conscious form of brain functioning.  A memory bias is a cognitive bias that either enhances or impairs the recall of memory.  Memory is highly selective.

Memory Formation
There are different ways of encoding information to memory and how a particular memory is encoded will determine how accurately it is remembered.  This is the levels-of-processing effect. False information or misinformation can affect people's reports of their own memory (misinformation effect).  Missatribution and source confusion refer to situations in which memory detail is retained but the source of the memory is not or cannot be later recalled. That snippet of information may become associated with a wrong event in time.  Suggestibility is a form of misattribution where ideas suggested by a questioner are mistaken for real memories.  A false memory is misattribution where an imagined event is mistaken for a memory.

The picture superiority effect says that concepts are more likely to be remembered experimentally if they are presented in picture form.  This might be one of the reasons I like to present my thoughts in that way, for example on this blog.  There is a link between emotion and memory.  The bizarreness effect is one where bizarre material is better remembered than common material.  This is similar to the humour effect, where perhaps the distinctiveness and the emotional stimulus associated with humour make it more memorable.  The Von Restorff effect states that an item that sticks out is more likely to be remembered than other items.

Emotions and perhaps memories associated with unpleasant events tend to fade faster than those associated with happier events.  This is the fading affect bias.  This might also explain the positivity effect and rosy retrospection, where older adults favour positive over negative information in their memories.  One's current emotional state can also affect one's ability to recall information (mood-congruent memory bias).  Information which is heard frequently is likely to be remembered as fact even if it is fiction.  This is the illusion of truth effect,  Self-generated information is more easily remembered than information which has come from another source.  This is referred to as the generation effect.  Illusory correlation is inaccurately remembering a relationship between two events.  Interestingly it has been found that tasks which have been completed are remembered less clearly than those which are uncompleted or interrupted (Zeigarnik effect).

Memory Modification and Recall
Levelling and sharpening are memory distortions that may coexist.  Sharpening is the selective recollection of certain aspects which then become exaggerated or take on a greater relevance than aspects which have been levelled and lost.  The repeated retelling of the memory may further exaggerate the effects.  Seems akin to repeatedly re-saving a lossy JPEG image file.    Verbatim effect is the tendency not to recall an exact wording but the general gist or context of the memory.  Tip of the tongue phenomenon, where we know a memory is right there but we cant quite grab it, is believed to be due to multiple related memories blocking and preventing the memory we want from being retrieved.

The peak-end rule is another interesting aspect of memory recall.  We tend not to recall the sum of an experience but the average of how it was at it's peak and also how it ended.  We have a greater tendency to recall items near the end of a list (primacy effect/recency effect/serial position effect) which is why it is always handy to be at the end of a job interview process. Conservative or regressive bias affects memory by remembering higher values and higher probabilities as being lower than they actually were. Consistency bias is incorrectly remembering one's past attitudes and behaviours as resembling present attitude and behaviour.  Egocentric bias is a recall of the past in a self-serving manner.  The hindsight bias is the inclination to see past events as being predictable.  Memory is often associated with context and is often retrieved by triggering contextual memory pathways.  This is the context effectTelescoping effect is the tendency to displace recent events backwards in time and remote events forward in time.

All these biases might paint the picture that memory and recall is totally unreliable.  There are tricks to improving and perfecting memory, including the testing effect - frequent testing of information that has been committed to memory improves memory recall.  The spacing effect refers to one such mode in which information is better recalled if exposure to it is repeated over a longer span of time. The method in which information is received can affect how it is retained eg. whether heard, viewed or read (modality effect) which is why writing down information can aid in consigning it to memory ... possibly worth combining with a sketch and a bit of humour!

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