We have AI to read books for us now, of course. But in the olden days, many humans would curl up with a bound set of paper and read the words on it. Reading actual books for pleasure is less popular than ever, though many of us still do it!

As Time magazine reports, reading books is associated with health benefits. The journalist drops some causal language into their summary, so let’s decide if that is warranted as we learn about the science. They start out strong with causal language about the “impacts” and “effects” of book-reading:

But a new review published in Psychological Medicine suggests that reading for pleasure—sitting down and focusing on a book you actually look forward to cracking open—can have significant impacts on your brain and wellbeing. 

[…]Reading has an effect from a very young age, says Barbara Sahakian, an emeritus professor of clinical neuropsychology at the University of Cambridge in the U.K. and an author of the new paper. In one study of about 10,000 children in the U.S., she and her colleagues found that kids who started to read for pleasure early in life were better adjusted later, regardless of their socioeconomic background. “They had better cognition, they had reduced symptoms of mental-health problems, they had better attention,”

And here’s another causal claim:

Some of the research Sahakian finds most exciting focuses on older people’s reading habits. She refers to one study in Taiwan that followed people over age 64 for 14 years. “People who just read once a week had a significantly reduced risk of cognitive decline over that 14-year period, and importantly, it didn’t relate to educational levels,” she says. “What is so good about reading is that you get these benefits regardless of socio-economic background or educational level. It will improve your brain. It will improve your cognition. It will improve your well-being,” she says.

Questions

a) Start with the claim in the last paragraph about the study in Taiwan. What are the three variables in this study? Were they measured or manipulated (as far as you can tell)?

b) Is this study correlational or experimental?

c) Work through the three criteria for causation to determine if we can support the claim that “It will improve your brain”. First, why does the study have covariance? (use the term “results” in your answer):

d) Next, the method of this study does establish temporal precedence. Why?

e) Finally, the method of this study can rule out two internal validity threats, because they controlled for educational level and socioeconomic background. But there are other variables that might be responsible for this relationship. What C variables can you think of that might be associated with A (reading once a week) and B (rates of cognitive decline)? Name the C variable and explain how it is related to BOTH A and B.

f) Find another causal claim in the Time story (use the quoted text above or click through to read the original). Apply steps a through e to this new claim.

g) One could design an experiment to actually test this causal claim. What would you manipulate and what would you measure?