5 ms·

Not exactly an answer to your question, but a few studies report a weak positive correlation (around .3) between head size and IQ in humans. https://scholar.go

by sieste 4y ago

Not exactly an answer to your question, but a few studies report a weak positive correlation (around .3) between head size and IQ in humans. https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=correlation+head+size+iq&btnG= https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=corr...

svnt 4y ago
But several in your search, including the twin study, report no correlation, and others report correlation only within race and sex groups.
- clnq 4y ago
  If there's a weak correlation in a population, finding no correlation in some subpopulations and a stronger correlation in others is expected. For example, a very weak correlation between GPA and job performance exists. In some disciplines, like law, the correlation is strong. In other fields, like extreme medicine, there is no correlation.
  - astrange 4y ago
    Are there studies on GPAs of extreme medics? …Why? (And how much education did they have? The field includes people who have and haven't gone to medical school, I assume.)
    - clnq 4y ago
      No, this was meant to be an intuitive example of weak correlation. It could have been about a correlation between the redness of a fruit and its sweetness. For the entire population of fruit, it is weakly correlated. For some apples, it is strongly correlated. And for tomatoes, there is no correlation. Extreme medicine, which includes field, mountain, and battlefield medicine, is a specialization of general medicine. You can study it as a part of various programs. I studied it as a specialization in a general practitioner's MSc program in Central Europe. Depending on the region, it is probably possible to specialize in extreme medicine as a nurse or an EMT. There was a wide range of GPAs in that program because success was measured by a narrow range of criteria that did not include things usually considered "academic aptitude" - mainly the ability to follow resuscitation algorithms in simulations precisely. Some of the things we were scored by automatically were time to ECG, time to defibrillation, correct callouts to the team, intubation depth and time, and chest compression depth and rate. And failing to execute a particular algorithm meant immediate failure. Every other imperfection immediately meant a reduced score, and scoring was entirely metric-based in simulators, not open to human interpretation. Scoring just 45% of the possible grade on tests was considered excellent. You had to demonstrate very high competency to pass. Mediocre knowledge of algorithms or skills in resuscitation was unacceptable because that would severely worsen the outcomes of actual patients. If you either cared about your GPA or were primarily motivated by your GPA at school or university, it was clear that this would be a very difficult specialization for you. It was more for people who excelled in algorithm following, composure under stress, and perseverance; and those who wanted a high skill ceiling.
      - fsckboy 4y ago
        you are suggesting that "caring about GPA" is what leads to high GPA. That's like suggesting that "caring about scoring stats" is the key to what leads athletes to accumulate high scoring stats.
        clnq 4y ago
        Certainly. Students who care about their GPA will put more effort into maintaining a high one. I am not claiming it is the only GPA determining factor.
  - svnt 4y ago
    Twins should be the ultimate check in whether head size actually means anything (otherwise it could just as easily be nutrition, sleep, or other factors that generally lead to growth).
    - Retric 4y ago
      Depends on how sensitive the studies are. The pool of twins with significantly different brain sizes is presumably limited.
    - JumpCrisscross 4y ago
      > twins should be the ultimate check in whether head size actually means anything (otherwise it could just as easily be nutrition, sleep, or other factors that generally lead to growth) Twins are great for ruling out genetic factors. It may still be the case that neonatal nutrition drives both head size and adult IQ.
- airgapstopgap 4y ago
  It's a solved question. Of course brain size relates to intelligence, albeit noisily. What, why do people assume that the increase in brain volume in the evolutionary record, concurrent with the increase in sophistication of material culture, doesn't set a prior for within-species effects of variance in this trait? Do we have another computational substrate besides brain contents? Would this skepticism be considered reasonable in the context of any other tissue and its quantifiable function, like muscle or bone? This is the most up-to-date meta-analysis on the topic: https://royalsocietypublishing.org/doi/10.1098/rsos.211621 https://royalsocietypublishing.org/doi/10.1098/rsos.211621 > Brain size and IQ associations yielded r = 0.24, with the strongest effects observed for more g-loaded tests and in healthy samples that generalize across participant sex and age bands.
  - Teever 4y ago
    > Would this skepticism be considered reasonable in the context of any other tissue and its quantifiable function, like muscle or bone? let's run with that idea. I have more muscle in my legs so I must be faster than a rabbit?
    - airgapstopgap 4y ago
      Not necessarily faster, but you definitely have way more leg power. Various hypotheses on how a larger brain is actually used to control a larger body and thus doesn't translate into specific "brain power" usable for intelligent activities are unsound.

by sieste 4y ago

svnt 4y ago

But several in your search, including the twin study, report no correlation, and others report correlation only within race and sex groups.

clnq 4y ago
If there's a weak correlation in a population, finding no correlation in some subpopulations and a stronger correlation in others is expected. For example, a very weak correlation between GPA and job performance exists. In some disciplines, like law, the correlation is strong. In other fields, like extreme medicine, there is no correlation.
- astrange 4y ago
  Are there studies on GPAs of extreme medics? …Why? (And how much education did they have? The field includes people who have and haven't gone to medical school, I assume.)
  - clnq 4y ago
    No, this was meant to be an intuitive example of weak correlation. It could have been about a correlation between the redness of a fruit and its sweetness. For the entire population of fruit, it is weakly correlated. For some apples, it is strongly correlated. And for tomatoes, there is no correlation. Extreme medicine, which includes field, mountain, and battlefield medicine, is a specialization of general medicine. You can study it as a part of various programs. I studied it as a specialization in a general practitioner's MSc program in Central Europe. Depending on the region, it is probably possible to specialize in extreme medicine as a nurse or an EMT. There was a wide range of GPAs in that program because success was measured by a narrow range of criteria that did not include things usually considered "academic aptitude" - mainly the ability to follow resuscitation algorithms in simulations precisely. Some of the things we were scored by automatically were time to ECG, time to defibrillation, correct callouts to the team, intubation depth and time, and chest compression depth and rate. And failing to execute a particular algorithm meant immediate failure. Every other imperfection immediately meant a reduced score, and scoring was entirely metric-based in simulators, not open to human interpretation. Scoring just 45% of the possible grade on tests was considered excellent. You had to demonstrate very high competency to pass. Mediocre knowledge of algorithms or skills in resuscitation was unacceptable because that would severely worsen the outcomes of actual patients. If you either cared about your GPA or were primarily motivated by your GPA at school or university, it was clear that this would be a very difficult specialization for you. It was more for people who excelled in algorithm following, composure under stress, and perseverance; and those who wanted a high skill ceiling.
    - fsckboy 4y ago
      you are suggesting that "caring about GPA" is what leads to high GPA. That's like suggesting that "caring about scoring stats" is the key to what leads athletes to accumulate high scoring stats.
      - clnq 4y ago
        Certainly. Students who care about their GPA will put more effort into maintaining a high one. I am not claiming it is the only GPA determining factor.
- svnt 4y ago
  Twins should be the ultimate check in whether head size actually means anything (otherwise it could just as easily be nutrition, sleep, or other factors that generally lead to growth).
  - Retric 4y ago
    Depends on how sensitive the studies are. The pool of twins with significantly different brain sizes is presumably limited.
  - JumpCrisscross 4y ago
    > twins should be the ultimate check in whether head size actually means anything (otherwise it could just as easily be nutrition, sleep, or other factors that generally lead to growth) Twins are great for ruling out genetic factors. It may still be the case that neonatal nutrition drives both head size and adult IQ.
airgapstopgap 4y ago
It's a solved question. Of course brain size relates to intelligence, albeit noisily. What, why do people assume that the increase in brain volume in the evolutionary record, concurrent with the increase in sophistication of material culture, doesn't set a prior for within-species effects of variance in this trait? Do we have another computational substrate besides brain contents? Would this skepticism be considered reasonable in the context of any other tissue and its quantifiable function, like muscle or bone? This is the most up-to-date meta-analysis on the topic: https://royalsocietypublishing.org/doi/10.1098/rsos.211621 https://royalsocietypublishing.org/doi/10.1098/rsos.211621 > Brain size and IQ associations yielded r = 0.24, with the strongest effects observed for more g-loaded tests and in healthy samples that generalize across participant sex and age bands.
- Teever 4y ago
  > Would this skepticism be considered reasonable in the context of any other tissue and its quantifiable function, like muscle or bone? let's run with that idea. I have more muscle in my legs so I must be faster than a rabbit?
  - airgapstopgap 4y ago
    Not necessarily faster, but you definitely have way more leg power. Various hypotheses on how a larger brain is actually used to control a larger body and thus doesn't translate into specific "brain power" usable for intelligent activities are unsound.