Posts tagged memory
I have been reading the excellent book ‘The mind of an ape‘ by David and Ann Premack and also enrolled in a MOOC tiled ‘Origins of the human mind’ offered by Dr. Matsuzawa, so apes have been on top of my mind recently.
Prof Matsuzawa describes an experimental procedure where numerals from 1 to 9 are very briefly displayed on the screen and then masked and the chimpanzee is required to touch the numerals, displayed randomly on the screen briefly, and now invisible as are masked, in ascending order. The chimpanzee is able to perform the task at 80% accuracy, a feat at which if human subjects try they can never succeed (humans perform at 0% accuracy).
We typically pride ourselves as being the epitome of civilization and cognitive abilities, but its humbling to find that there are tasks at which the chimpanzee can excel! This task, in particular, requires immediate memory (sensory/short-term memory) which it seems is better in the chimp.
The different experiments on the chimp also made me think about the underlying structure of memory and reasoning systems. Like humans, it seems chimps too have two different reasoning systems- one tuned to physical world and the other to social/agentic world.
The physical reasoning system is attuned to thinking about causal reasons between psychical objects and events. The question of concern is ‘what caused what?’ . One needs to have a (rudimentary) theory of cause and effect. Some basic understanding of physics is necessary and is instrumental in the development of the capacity of tool use. As a matter of fact too use is one of the ways this physical reasoning system is studied.
The social /agentic reasoning system is attuned to thinking about other con-specifics/ living creatures. It attributes intentions to people and answers ‘who did what to whom?’. One needs to have a (rudimentary) theory of mind to know that others have intentions/ beliefs/ desires etc. A simple paradigm to measure this is whether one understands the visual gaze of a person and can take his/her perspective and know whether the other is able to see something or not.
The physical and social reasoning systems have been show to be different and dissociated in humans and as per one theory are differently accentuated in autistic (more physical reasoning) and schizophrenic (more social reasoning) mind.
Another ability where chimps and humans markedly differ is in their abstract/symbolic representations and linguistic abilities. While chimps can be taught language to a great extent, they don’t develop symbolic language naturally. Language requires abstract and symbolic representation. One can contrast this with the immediate/imaginal representation.
Again, while autistic people have a good immediate/imaginal (thinking/seeing in images instead of words/ symbols) representation system (for e’g’ like in movie ‘rain man’ they can tell the exact number of matchsticks dropped on the floor without counting), their language development is typically hampered , perhaps due to deficits in the abstract/semantic/symbolic representation system.
Thus we see two sets of cognitive functions, and the two sets seem to be slightly at odds with each other: Physical reasoning and concrete/ immediate/imaginal representation; and social reasoning and abstract/semantic/ symbolic representation.
The species (chimps/humans) who are good at imaginal and physical reasoning system may not be as good at symbolic and the social reasoning system. Similarity within the human family, autistic and schizophrenics may excel at different such functions. While we lost or never gained the ability for highly accurate imaginal system since around 5 MYA when we diverged from chimps and bonobos, we gained the ability for abstract/ symbolic representation. Given the limited real estate that the brain can occupy in any body, its inevitable that as you evolve you lose some and you gain some abilities. Like we lost the ability to use four hands that chimpanzee has.
To summarize, one can associate and link the above to human memory systems. One can conceive of four such memory/reasoning systems:
- Visuo-spatial/ short term/ sensory memory: related to immediate memory and imaginal representation.
- Procedural memory: related to Physical reasoning/ tool use /physical skills etc and objects representations.
- Episodic memory: related to social reasoning and agent representations.
- Semantic memory: related to language and symbolism and abstract representations.
Its easy to see how we can apply the same memory/reasoning model to chimps/ other apes without necessarily anthropomorphism. And its equally hard to see and admit that chimps may be better than us at certain cognitive functions and tasks.
I have earlier written about the entrepreneurial roller-coaster and how when entrepreneurs are in a happy mood, they focus on long-term vision related creativity; while when they are in negative mood they focus on the task at hand. I had also tried to relate this to prevention and promotion focus and weave it in the narrative of preventive focus as depressive and promotion focus as being manic in nature.
Another bit of research extends the thesis and adds to our knowledge base. This new article by Winkielman et al suggest that people in sad mood tend to value familiarity whereas those in a happy mood are more open and welcoming of novelty.
Here is the abstract of the study:
People often prefer familiar stimuli, presumably because familiarity signals safety. This preference can occur with merely repeated old stimuli, but it is most robust with new but highly familiar rototypes of a known category (beauty-in-averageness effect). However, is familiarity always warm? Tuning accounts of mood hold that positive mood signals a safe environment, whereas negative mood signals an unsafe environment. Thus, the value of familiarity should depend on mood. We show that compared with a sad mood, a happy mood eliminates the preference for familiar stimuli, as shown in measures of self-reported liking and physiological measures of affect (electromyographic indicator of spontaneous smiling). The basic effect of exposure on preference and its modulation by mood were most robust for prototypes (category averages). All this occurs even though prototypes might be more familiar in a happy mood. We conclude that mood changes the hedonic implications of familiarity cues.
The authors reasoning is as follows:
Happy or sad mood signal the safety of the environment.
Much psychological research points out that one signal of environmental safety or danger is an individual’s mood (e.g., Clore, Schwarz, & Conway, 1994; Schwarz, 2002). Bad mood signals a problem, tuning individuals toward safety concerns, whereas good mood signals that an environment is benign. Tuning accounts assume that mood adjusts cognitive and affective reactions so that they best serve the individual in the specific context.
In a safe environment, one can experiment or value novelty. In an unsafe environmental it makes sense to stick to tried and proven things.
After all, familiarity is only a heuristic cue to safety. Thus, as with any heuristic cue, its validity and hedonic meaning vary by context (Hertwig, Herzog, Schooler, & Reimer, 2008). Specifically, the familiarity-positivity link should depend on whether individuals are tuned toward safety concerns. Familiarity should be valued in an unsafe environment, but less so in a benign environment (e.g., Bornstein, 1989). Analogously, in a strange city a familiar face elicits a warm glow, whereas locally the same face prompts a yawn. Numerous studies (and parents) have observed that in unsafe environments infants are neophobic, but in safe settings, they are less so (Shore, 1994). Similarly, in multiple species, stress increases neophobia, whereas comfort reduces it.
Thus they hypothesize that sad mood should lead to mare liking for familiarity while happy mood should lead to novelty preference. They do some clever experimentation and get exactly the same result.
To me this is extension of promotion focus is expansive, is happy, is creative and long-term, and is novelty preferring versus prevention focus is restrictive, is sad, is focused on the task at hand, and is familiarity preferring. In other words people in safe environments having promotion focus are manic while those in unsafe environments and having prevention focus are depressive.
Another finding that struck out from the current paper was that the (false) memory for prototype was increased in positive mood condition. This is congruent with the fact that the promotion focus / mania condition has a more narrative focus that tries to weave a narrative around things and remembers a gist rather than is accuracy based and tries to recall the exact events. thus, I believe the risk of delusions and hallucinations magnifies as one goes deep into promotion focus / mania and starts weaving narratives and having false prototypical memories of events/happenings.
de Vries, M., Holland, R., Chenier, T., Starr, M., & Winkielman, P. (2010). Happiness Cools the Warm Glow of Familiarity: Psychophysiological Evidence That Mood Modulates the Familiarity-Affect Link Psychological Science DOI: 10.1177/0956797609359878
The Society for Neuroscience(SfN) was formed 40 years ago and to commemorate the occasion, the journal of Neuroscience has made some review articles open-access. They are written by leading luminaries in their filed and are somewhat scholarly- though I found some of them pretty accessible too.
Two articles relate to reviewing memory research in the past 40 years and both are a pretty good read. The first is written by Larry Squire and gives you a broad overview of memory research. The second by Eric Kandel focuses more on the molecular aspects of memory formation- but is an excellent article and ends with 11 still unresolved questions for the next 40 years in the memory research.
There is another article by Marcus Raichle that I found pretty interesting, partly because of my continuing fascination with the default brain network and the intrinsic activity of the brain. this again is a very accessible article that brings one up to speed on the 40 yrs of imaging with special focus on the default brain network.
There are other retrospectives there including one on neurotransmitters so go to the source and enjoy the ride.
Hat Tip: Mind Hacks
Squire, L. (2009). Memory and Brain Systems: 1969-2009 Journal of Neuroscience, 29 (41), 12711-12716 DOI: 10.1523/JNEUROSCI.3575-09.2009
Kandel, E. (2009). The Biology of Memory: A Forty-Year Perspective Journal of Neuroscience, 29 (41), 12748-12756 DOI: 10.1523/JNEUROSCI.3958-09.2009
Raichle, M. (2009). A Paradigm Shift in Functional Brain Imaging Journal of Neuroscience, 29 (41), 12729-12734 DOI: 10.1523/JNEUROSCI.4366-09.2009
Jonah Lehrer, has an article in this week’s Nature News, (find a PDF here) , regarding 30 or so cognitively enhanced mice strains that have been bred and genetically engineered. As Lehrer very elaborately documents, all these have enhanced LTP as an intervening mechanism that leads to improvements in learning and memory. Most of the genes involved affcet the LTP mechanism in one way or the other to breed super mnemonist mice. However, from the time of Luria, t has been well known that those who have enhanced memory also suffer from some of its disadvantages and that the ability to forget is also very important.
Little is known about the side effects and tradeoffs of both the current usage or the drugs in development, but initial clues offered by smart mice raise concerns. The Hras strain developed in Silva’s lab might be good at learning, but its fear response for a relatively benign stimulus would be counterproductive for a wild mouse. Its enhanced memory is both a blessing and a burden. Silva cites other strains of smart mice that excel at solving complex exercises, such as the Morris water maze, but that struggle with simpler mazes. “It’s as if they remember too much,” he says — possibly taking in irrelevant information such as the position of windows or lights but missing the big clues.
Farah sees a parallel between these mice and one of the few case studies of an individual with profoundly enhanced memory. In the early 1920s, the Russian neurologist Alexander Luria began studying the learning skills of a newspaper reporter called Solomon Shereshevsky, who had been referred to the doctor by his editor. Shereshevsky had such a perfect memory that he often struggled to forget irrelevant details. After a single read of Dante’s Divine Comedy, he was able to recite the complete poem by heart. Although this flawless memory occasionally helped Shereshevsky at work — he never needed to take notes — Luria also documented the profound disadvantages of such a capacious memory. Shereshevsky, for instance, was almost entirely unable to grasp metaphors, as his mind was so fixated on particulars. When he tried to read poetry, for example, “the obstacles to his understanding were overwhelming”, Luria wrote in his book The Mind of a Mnemonist. “Each expression gave rise to a remembered image; this, in turn, would conflict with another image that had been evoked.”
For Luria, Shereshevsky’s struggles were a powerful reminder that the ability to forget is as important as the ability to remember. Enhancing human memory in individuals without severe cognitive defects might prove counterproductive.
It is interesting to pause here and note that many savants who have excellent memory are also autistic and that schizophrenics on the opposite end of the spectrum are characterized by too much reliance of metaphors and too much generalizations and abstractions. Further Martha Farah notes the following:
Many scientists are concerned that the animal models of enhanced cognition might obscure subtle side effects, which can’t be studied in rodents or primates. Farah is currently looking at the trade-off between enhanced attention — she gives human subjects a mild amphetamine — and performance on creative tasks. Other researchers have used computer models to show that memory is actually optimized by slight imperfections, as they allow one to see connections between different but related events9. “The brain seems to have made a compromise in that having a more accurate memory interferes with the ability to generalize,” Farah says. “You need a little noise in order to be able to think abstractly, to get beyond the concrete and literal.”
Again, one can easily see the correlations with Autism and Schizophrenia- one end marked by too narrow a focus , while the other marked by too much noise and divergent creativity. I would have been happy to incorporate the more LTP as autistic and less LTP as schizophrenics, but it flies in face of my earlier findings regarding experience dependent plasticity in autism and schizophrenia where the conclusions were just the revers. Yet, it is clear that synaptic plasticity is a majo mechanism involved in the autism/psychosis differentiation. Do let me know if you can reconcile the new findings with the older ones to come up with the right LTP and psychosis/autism relationship.
Today I discovered a new educational video portal,WatchKnow, that aggregates educational videos in categories. The psychology category has about 14 or so videos and one video that caught my fancy was a video by New Scientist that demonstrates the Rubber Hand illusion.
This becomes pertinent in light of a post today by Mind Hacks about new research that showed that rubber hand illusion can be induced in amputee, for a robotic arm, and the effcet is the same rubber hand illusion extended.
Another series of videos I liked were BBC‘ Horizon series on Memory, where I found for the first time that Memory was correlated with self-recognition (mirror test) in children.
The part 2 and part 3 of the above clip are about a memento style John , who cannot form memories adequately and an eternal sunshine of the spotless mind type lady who needs to get her PTSD memories erased.
There are more available at the source, so go have a look!