Morons on Neuroscience

See this comment over at Scalzi’s site.

This is why I love having a degree in Cognitive Psychology with an emphasis in neurology, because it lets me be fully justified when I point out the stupidity of statements like

There are judgements adults can make that children and even adolescents simply do not have the brain structures to make.

That’s utterly hilarious. The final stages of brain development, initiated at puberty, involve the destruction of connections and the massive pruning of redundancy. Adults have less potential and fewer brain structures than children and early adolescents, which is why they cannot pick up languages easily through casual experience, cannot learn to identify phonemes not present in their native languages, and have a very difficult time adopting or abolishing their existing accents and pronunciations.

There’s a tradeoff involved: greater speed and efficiency for impaired flexibility and potential. If you haven’t developed the capacity to do things once the pruning takes place, generally you never will. The late neural pruning exhibited by human beings is a major factor in our increased intelligence and flexibility compared to the majority of animals – the period in which they can learn and adapt is extremely limited, far more so than our own.

In adolescence, the brain changes from the child form to the adult form essentially from the back forwards: the old brain first, the new brain last. (Call that an example of ontogeny recapitulating phylogeny if you want.) Teenagers develop the ability to do crazy skateboard tricks YEARS before they develop the sense NOT to do them. The part of the brain that successfully predicts the consequences of actions develops only very late in adolescence, in fact one might say that the completion of that development IS the completion of adolescence.

Those ‘final stages of development’ involve the loss of the ability to develop functional systems, not their development. A person who hasn’t developed functional frontal structures by the time the pruning occurs will never do so. It in no way follows that the functional structures have not developed before the pruning – in fact, the existence of adults with effective frontal lobes is the definitive demonstration that such development occurs.

In terms of the legal definitions of child and adult, the distinction is arbitrary, having nothing to do with individual competence. There are lots and lots of adults that lack the competence it’s assumed they have because of their age, and lots and lots of legal minors who are far more competent than the adult average.

Hell, most adults never progress beyond concrete reasoning, even in advanced countries. It’s even worse in more primitive societies.

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6 Responses to “Morons on Neuroscience”

  1. Ahem… Bullshit.

    The structures necessary for complex reasoning aren’t fully developed until 23 or so.

    But do feel free to wave around a BA from a Cracker Jack box to refute actual neurobiological research.

    (Also, your arguments sound suspiciously like those developed by people who want the “right” to have sex with underage kids and therefore have come up with bizarre interpretations of research to assert that kids have ability to consent. Surely that’s not your motivation?)

    • Ahem… Bullshit.

      The structures necessary for complex reasoning aren’t fully developed until 23 or so.

      Misrepresentation. “Full development” involves pruning and the crystalization of capacities. What matters is whether the structures can function properly – and people reach their maximum level of reasoning at all sorts of ages, ranging from early to very late adolescence.

      The actual neurobiological research does not contradict the actual behavioral and developmental research, which shows that many adults have the minds of “children” and adolescents often are not only as good at reasoning as they’re ever going to be, but can be significantly better than some legal adults.

      Your further question is beneath contempt.

  2. michael vassar Says:

    Wow what an idiotic ad hominem from Tal!

    That said, it’s clear that the ability to make a judgment isn’t the same thing as the ability to percieve a new class of input.
    Also, zero and one contain the same data. The loss of a neuron or a connection can add information to a brain.
    “Those ‘final stages of development’ involve the loss of the ability to develop functional systems, not their development.” is a false dichotomy. The same physical process can be the loss of the ability to develop systems AND the development of either the same or different systems.

    • That said, it’s clear that the ability to make a judgment isn’t the same thing as the ability to perceive a new class of input.

      Of course it’s not the same thing in all ways.

      But the generation of regulatory structures is what makes rational judgment possible. The ability to generate a structure that responds usefully to incoming data is vital both in hearing phonemes and choosing wisely.

      The loss of a neuron or a connection can add information to a brain.

      So? The information content of the brain is not what’s being discussed here.

      “Those ‘final stages of development’ involve the loss of the ability to develop functional systems, not their development.” is a false dichotomy.

      No, it isn’t. You’re confusing the “system as it functions” with “the systems needed to make it function differently”.

      Before the language-processing centers are fully ‘mature’, they can develop to recognize and respond to all sorts of linguistic data. The final maturation process involves the loss of the ability to adapt and respond to a wide variety of stimuli. The ability to funtion generally is lost in exchange for a heightened specific functionality.

      Maximum performance is found before final maturation. Afterwards, performance is impaired – ideally, in ways that don’t matter, since the pre-maturation stage is supposed to involve identifying the specific tasks that the organism is likely to need.

  3. michael vassar Says:

    Maximum performance is a contextually dependent notion. Necessarily.
    http://en.wikipedia.org/wiki/No_free_lunch_theorem
    (ignore the mis-use by creationists)

    Look, here’s a hypothetical example.

    Immature organism needs to withdraw from poisonous jellyfish. Has built-in reflex to pull away from those jellyfish when it feels their poison. Later, develops cognitive pathways. Now the signal from the nerves sensing the poison goes through both the cognitive pathways, which could decide to withdraw or not, and through the reflexes, which are simple and cause withdraw before the cognition engages with the sensory input. Finally, pruning removes the reflex pathway giving the organism the ability to use its mature adult judgment in deciding when to withdraw.

    • We know, far beyond reasonable doubt, that the parts of the brain that undergo neural pruning are less flexible and in many cases incapable of adapting themselves to new stimuli regardless of how the environment changes or how important it is that they do so.

      Furthermore, we know that effective judgment is possible long before neural pruning takes place – through observation. Your hypothetical does not address the reality that we’re aware of.

      Try not to be described by the title of this post more than is necessary.

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