The main idea is to summarize current knowledge about workings of human memory, and what kind of deficiencies it has. The bulk of text is allocated to discussion of 7 specific features of human memory and problems in causes in contemporary live. The overriding notion, however, is that human memory is completely different from artificial carriers of sounds and images of the past such as photos. It has reconstructive rather than recording and reproducing character, meaning that human memory is recreated every time at the moment of remembering and includes not only reactivation of neural networks created at the moment in past, but multiple networks created much later, opening memory to manipulation and making it unreliable. However it is not a bug, but feature very important for human evolutionary fitness.
Introduction: A Blessing Bestowed by the Gods
It starts with the story of a writer who unexpectedly encounters woman and learns that she sincerely believes that they were lovers once in the town of Yumiura. He does not remember women, but initially believes her only to find out later that such town does not exists, so her claims could not be true. From here author moves to other examples of memory failures, consequently coming up with seven key transgressions: Transience, Absent-mindedness, Blocking, Misattribution, Suggestibility, Bias, and Persistence. This book is a detailed look at memory transgressions based on results of latest research and logic of evolutionary fitness applied to explain these results.
- The Sin of Transience
The chapter on transience looks at foundational research of Ebbinghaus who produced experimental evidence of transience long time ago in 1885. This followed by formal diary based research to demonstrate reconstructive character of human memory and our ability to reshuffle, include, and/or exclude actual artifacts of our lives that left traces in the memory into this process. As example author reviews cases of Bill and Monica, various memory problems of baby boomers with research based on age groups comparison on memory tests. Afterword discussion goes into technical side of memory formation based on fMRI technology. At the end author provides some mnemonics to decrease memory transience.
- The Sin of Absent-mindedness
The second sin of memory is absent-mindedness nicely demonstrated by example of inability of National Memory Champion who is capable to remember huge amounts of information, at the same time forgetting to carry on simple tasks. The simple explanation seemingly supported by fMRI is the human tendency to automate familiar tasks by pushing them into unconscious. In short absent mindedness highly linked to attention paid or not paid to a subject. It also linked to event based prospective memory. In other words if intention to do something linked to an event that supposed to occur in the future, the possibility of realizing this intent usually increased. Another effective tool is to post reminders and to do planning.
- The Sin of Blocking
Blocking is inability to access something that one knows that he knows, but just cannot retreat from memory at the moment. Typical examples are names of people and objects. Often individual not only knows, but also can describe in details different characteristics, but fails to reproduce the name of an object. Author also discussing issue of suppressing painful memories, eventually concluding that recent phenomenal interest in this issue somewhat unjustified since there is very little scientific support of reality of suppression in healthy people, however it was demonstrated in individuals with damaged brains.
- The Sin of Misattribution
A typical misattribution case is when people remember things that never really happened. The experimental research demonstrated that it happens when brain files up gapes in the memory with something that logically fit based on previous experience. It is often the case with eyewitnesses of crimes. The real perception of events in this case is always fragmented and unclear because attention is not concentrated on details that witness is asked about during interrogation, so brain adds whatever is necessary to build complete picture. Author describes very interesting studies using fMRI and PET scanning in attempt to separate actual memory from later additions and misattributions. Similar problem occur when individual has brain damage causing difficulties in image recognition and/or false recognition such as seeing movie starts everywhere. Another interesting example is subconscious plagiarizing when people forget that they actually encountered some ideas and even texts in other individuals’ works and sincerely believe that they produce these ideas themselves.
- The Sin of Suggestibility
This is probably one of the most difficult to accept features of human brain when false memories could be planted intentionally or unintentionally so a person believes that something happened, which never really did. It is widely used in police investigation often leading to miscarriage of justice. Author discusses in details a famous case in 1990s when teachers were imprisoned after investigators managed to plant false memories of sexual abuse into minds of their students.
- The Sin of Bias
This problem as many other relates to the nature of memory as continuously constructive process when result is highly susceptible to impact of the new information obtained well after events under review. Author provides multiple examples from Ross Perot supporters’ modified memories of what they believed before his drop out from election bid, to memories of pre-game anticipation of Red Sox fans. In all cases the after event memories of pre-event believes are markedly different from actually recorded pre-game attitudes and believes. The typical human approach: “I knew it all along”. The sin of bias relates not only to the memory, but also to real time attitude and processing of perceptions. Author provides a wonderful example of impact of received information on behavior when inconsistency of such information with bias overrides biased attitude. The story goes like this: being a black man and walking at the night on the street in nice area author noticed fear that he generated in people he encountered who tried to avoid approaching him. However after he started whistling some melody from Vivaldi, the attitude changed dramatically. Instead of fear and vigilance he saw smiles and sympathetic interest. Obviously nothing changed in color of his skin, or dress, or anything, except that sound of baroque music sent signal that author is member of educated, non-violent, and friendly American middle class, rather then member of inner city violent lower class. Author also brings in split-brain studies to demonstrate that bias it one of regular methods of brain to make sense of environment with high levels of informational deficiencies.
- The Sin of Persistence
This one is about persistent memories that people have difficult time ridding off. Often it linked to traumatic events that had dramatic impact on individuals’ lives and consequently is continuously rerun in the memory in search of solution of the problem decreasing or even removing this impact. This memory feature is highly related to PTSD when memories practically torture people until some resolution is found.
- The Seven Sins: Vices or Virtues? End Matter
In the final chapter author not only suggests that all reviewed memory sins are also virtues from evolutionary point of view and goes on to demonstrate how all these sins could be instrumental in human survival and promote evolutionary fitness.
MY TAKE ON IT:
It is very nice catalog of performance consequences of the simple fact that human memory technically is just reactivation on demand of randomly connected neural networks related to remembering event or fact. Consequently all memory sins look consistent with this idea and support evolutionary fitness. Here is how it happens in my opinion:
- Transience – every bio-electro-chemical network tends to deteriorate over time and without constant reactivation its ability to recreate original signal deteriorate correspondingly.
- Absent-mindedness – The is quite a narrow bandwidth between human receptors and environment therefore attention is very important in order to pick up key features of environmental situation at any moment. As soon as something ceases to be such key feature, it is out of memory and gets missed.
- Blocking – this is just a consequence of incomplete activation of neural network related to specific memory. The typical cause would be that instead of being invoked by unconscious mind and taking time before bringing it to the forefront, memory if consciously activated, for example in response to external questions. In this case brain just did not have time to fully activate all parts of related network.
- Misattribution – this one is probably the most interesting feature of human brain because it somewhat proves that memory is reconstruction, rather than retraction of previous state. In short activation of network related to memory at the time of its creation also activates related networks created much later.
- Suggestibility – It probably has the same mechanism as Misattribution with difference being conscious implant of additions and/or substitutions to existing memory network by external interlocutor.
- Bias – this is a wonderful and very important tool absolutely necessary in dealing with unknown. Without bias, correctly understood as ability to build future scenario of outcome from encountering unknown based on previously accumulated information, it would not be possible to survive. For example a human in natural environment who encountered unknown individual of big cat species would be fine if acts according to bias against big cats being predators, but would probably not live long if try to overcome bias and treat the cat too friendly.
- Persistence – Finally persistence of memory is probably a result of activation of critical networks related to survival that basically command to replay the painful memory again and again in order to find reliable solution in case of encountering situation again. Interestingly enough it seems that latest and most successful approach to treating PTSD is to replay situation multiple times until it become somewhat routine and response to it well defined. As soon as this response fully incorporated in survival toolkit, the emotional networks critical for survival cease to be activated when related memory invoked.
In short our memory is just part of survival machinery of hunter gatherers which works just fine as selected by evolutionary process, but need some external enhancements to make it effective in contemporary live.