Puzzles and language

  A recent article in New Scientist highlights some very interesting research by Gillian Forrester at Birkbeck, University of London.  She has been developing puzzles to test the ability of great apes (including human children) to use their hands to solve increasingly complex puzzles, designed to test conceptualizing abilities similar to those required for language learning and use.  The evidence she has garnered through this (and earlier) research supports the claim that sign language developed prior to vocal language, and further suggests a role for puzzle-solving ability.  This short video gives a flavor of her work: 

https://youtu.be/8edayRfe484 

If Robin Dunbar is correct in his claim that language evolution was driven primarily by the pressures of living in large and complex social structures, Forrester’s work would seem to suggest that solving social puzzles is related to solving physical puzzles.  I’m looking forward to the publication of Forrester’s work for further details!  

Fatigue

  I just read an interesting review (in The New Scientist) of recent research on fatigue.  I’ve always considered feelings of fatigue to be based only on depleted energy supplies and accumulated “waste” chemicals in the muscles.  Recent research suggests it is more complicated; several brain systems are involved. In addition to the interoceptive reports on available energy and depletion of energy, reward systems assess the potential benefits of continuing the activity. A separate system balances the energy supply with the anticipated rewards in an on-going “cost/benefit analysis.”  The experience of being fatigued is the result of the brain’s assessment that the potential rewards of continued physical or mental effort do not justify the energy expenditure.  Anything that reduces the assessed reward value of the activity (such as depression or boredom) increases fatigue; anything that increases it (such as social encouragement – a cheering squad or the offer of monetary rewards) decreases the feeling of fatigue.  This helps explain why depression, which reduces the subjective pleasure of almost everything, is so enervating.

I have often noticed that the last mile of a hike seems especially long and tiring, whether it comes after three miles or fifteen miles.  The rewards of the hike (pretty views, birdsong, etc.) are all past, and apparently the reward of reaching the car and resting feels about the same regardless of how long the hike was.   

Dreaming – does it necessarily have a purpose?

  In his recent work Antonio Damasio has argued that the brain has evolved primarily as an organ for representing the body in its social and physical environment, and projecting that representation forward into the future.  The representation of the body Damasio writes about is story-telling, dynamic not static. Other researchers argue that a primary function of consciousness is to consider the potential outcomes of alternative actions as a basis for making decisions.  These ideas together suggest that the stories we invent in our dreams – both daydreams and sleeping dreams – are an extension of the process through which we represent and project forward our body’s physical and social presence.  

In “When Animals Dream” Peña-Guzmán argues that animals actually experience their dreams, and takes it as evidence that animals have some form of conscious experience, though the quality of that experience is likely to be quite different from that of human consciousness.  

I think it is reasonable to extend Damasio’s account of mental representation to dream behavior in both humans and other animals.  Perhaps, as Peña-Guzmán and others argue, dreams provide a way of consolidating mental representation, rehearsing behavioral responses, or both.  But it is also possible that the dream behavior is simply a continuation of forward-projection, disconnected from actual sensory input, so drawing its substance from random fragments of memory, sometimes but not always including memories of recent (e.g. yesterday’s) experience.  If that is the case, dreams may be simply an epiphenomenon, lacking any function at all - sometimes disturbing, sometimes entertaining.

Animal Dreams

  I’ve been reading “When Animals Dream” by David M. Peña-Guzmán.  The book summarizes an array of evidence supporting the claim that many animal species (not just mammals) do dream and evidence providing clues about the possible nature of those dreams – I will probably be writing more about it as I work my way through it. 

What especially caught my eye in the first chapter was Peña-Guzmán’s discussion of scientific resistance to the claim that the observed behavior is evidence of actual dreaming, comparable to the phenomenal experience of humans.  According to his analysis of the literature, the underlying issue pits phenomenology (the interpretation of behavior as experience) against a computational view in which the observed behaviors of sleeping animals is nothing more than the result of an algorithm running in the animal’s brain, associated with no subjective experience.  The sleeping animal jerks its legs, snaps its teeth, and so on – but does not experience any of this. 

I have recently criticized the computer model of human cognition (and the related code model of language and other signaling behavior); the algorithmic view of animal sleeping behavior criticized by Peña-Guzmán seems to be an extension of the computer model to animal brains, subject to many of the same criticisms.  It also seems part of the continuing ideology of human uniqueness, a defense of the sharp line between human and animal, that is becoming increasingly blurred as a result of new research in animal behavior, cognition, and communication.  

Reflections on memory loss and projection into the future

  A primary function of the brain is to maintain a representation of the state of the body in its physical and social environment and project that representation forward into the future, both short term and longer-term.  These processes depend on both long-term and short-term memory as well as current information from the senses, both external and internal.  They also depend on a story-telling capability, probably the same or closely connected with the more or less constant emergence of thoughts, including daydreams, that are often disconnected from whatever topic is the current focus of attention.  Most of us have a background knowledge of what we are likely to be doing both over the next few hours (short-term projection) as well as over a longer future time-span (long-term projection).  All of this is part of the cognitive context, background knowledge that contributes to how we understand relevant events, including communication.  We ordinarily pay attention only to what is relevant to current concerns and otherwise give little thought to this background mental “chatter” – until it stops.

In healthy young people the body usually repairs itself – and even the brain is able to repair minor damage, sometimes growing new neurons when needed.  As we age, this self-repair ability weakens, just as damage becomes more common.  Unfortunately, the brain seems especially susceptible to enduring damage.  Physical injuries, including concussions and penetration wounds, can destroy brain tissue.  Strokes are a common cause of damage, and they become increasingly common with advanced age.  Diseases, including Alzheimer’s, often cause a progressive damage to various brain tissues.  Any of these factors can result in loss of memory (short term, long-term, or both), impairment of language skills, partial or complete impairment of one or more perceptual senses, balance, social skills, reasoning, and so on.  

Patients whose short-term memory is impaired can have difficulty engaging in a coherent conversation, even when their language skills have not been impaired, because they can’t clearly recall what has already been said.  This can lead to repeatedly asking the same question or series of questions, in what becomes and endless loop (frustrating to family members and care-givers).  

The loss of short-term memory is also sometimes associated with inability to make or  recall plans, even plans based on ordinary routine (for example, lunch and socializing, followed by afternoon snack, followed by socializing, followed by dinner, followed by going to bed).  This suggests that the ability to project forward in time is related to memory or possibly part of memory.  Daily routine, and forward projection based on daily routines, appear to be closely related to short-term memory, and longer-term plans to long-term memory.  Cycles of the same question or comments like “I don’t understand” could be evidence of an impairment to reasoning functions, but they could also indicate a loss of the contextual knowledge in short-term memory.    

I’ve yet to find anything in the neurological literature that addresses this possibility, so it remains just an interesting speculation.