Saturday, 8 March 2014

If you don't believe that intelligence has declined by about one modern standard deviation in the past 150-200 years - then what DO you believe?

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1. Do you believe that Victorian simple reaction time (sRT) data are not comparable with modern data? If so, would you be convinced by evidence of rapidly slowing reaction times over recent decades, measured in one laboratory and using only modern RT machines? Because this kind of evidence is in the pipeline.

2. Do you believe that - despite about 140 years consensus that sRT and IQ are significantly correlated, and the general belief that this correlation is because general intelligence is dependent upon processing speed of which sRT is an indirect measure - there is NOT a causal relationship between simple reaction times and intelligence? That, therefore, average sRTs could be getting much, much slower but that this would not necessarily make any difference to average intelligence?

3. Do you believe that the measured decline in average simple reaction time from a Victorian sRT average speed of about 180 milliseconds (in several independent studies) to a modern average speed of 250 milliseconds (or slower), a slowing of 70 milliseconds plus - is not enough to be of interest: that it is too small to not reflect any significant or meaningful reduction in intelligence.

4. Do you believe that because the measured slowing of sRT over the past 150 years seems unexpected, and is larger than you would have supposed possible, strikes you as indeed ludicrous - that therefore we should simply ignore it?

5. Do you believe that - because the data on long term sRTs seems anomalous with your world view, that we should therefore assume that somehow there is something wrong somewhere with the Victorian to Modern comparison; and therefore we should just carry-on just as if we knew nothing about longitudinal changes in sRTs?

6. Do you believe that there has been a significant reduction in average general intelligence over the past 150 years, but that it is much less than one standard deviation - probably more like HALF a standard deviation? And the large size of the sRT slowing is just a Red Herring?

7. Do you believe that average intelligence has NOT changed over the past 150 years - that moderns have the same intelligence as Victorians? And the slowing of average sRT is irrelevant?

8. Do you believe that average intelligence has increased over the past 150 years despite slowing of sRTs, because you believe the pen-and-paper IQ tests are more valid, reliable and/or objective than reaction time data?

9. Or something else, or what?

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