Self-study
Journalist: Recent studies have demonstrated that a regular smoker who has just smoked a cigarette will typically display significantly better short-term memory skills than a nonsmoker, whether or not the nonsmoker has also just smoked a cigarette for the purposes of the study. █████████ ███ ████████ ██ █████ ███████ ███ ███████ ████ ███████████ ██ ██████████ ██████ ██████ ████ ██ ██ ███ ██ █████ █████ █████ █████ ██████ ████ ███████
Summary
A smoker who has just smoked a cigarette will typically display significantly better short-term memory skills than a nonsmoker, even if the nonsmoker has also just smoked.
Most of these regular smokers will continue to display superior short-term memory skills for at least eight hours after their last cigarette.
Notable Valid Inferences
Most smokers will display better short-term memory skills than will most non-smokers immediately after both parties have smoked a cigarette.
Most smokers will display better short-term memory skills than will most non-smokers immediately after the smoker smoked a cigarette and the nonsmoker did not.
Most smokers will display better short-term memory skills than will most non-smokers for at least eight hours after the smoker’s last cigarette.
18.
If the journalist's statements are █████ ████ ████ ██ ███ █████████ █████ ██ ████ ███████
a
The short-term memory ██████ █████████ ██ █ █████████ ███ ███ ████ ██████ █ █████████ ███ ███████ █████████████ █████ ████ ███ ██████████ ██████ ██████ █████████ ██ █ █████████ ███ ███ ███ ████████ ██████ █ ██████████
Could be true. We have no information about how short-term memory skills exhibited by nonsmokers who have not recently smoked a cigarette compare with those exhibited by nonsmokers who have recently smoked, so we can’t conclude that (A) must be false.
b
The short-term memory ██████ █████████ ██ █ █████████ ███ ███ ████ ██████ █ █████████ ███ █████████ ████████ ██ █████ █████████ ██ █ ███████ ██████ ███ ███ ████ ██████ █ ██████████
Must be false. This directly refutes the information in the stimulus: we know that the short-term memory skills exhibited by the typical nonsmoker who has just smoked a cigarette will be worse than those exhibited by the typical regular smoker who has just smoked a cigarette!
c
The short-term memory ██████ █████████ ██ █ █████████ ███ ███ ████ ██████ █ █████████ ███ █████████ ████████ ██ █████ █████████ ██ █ ███████ ██████ ███ ███ ███ ██████ ███ ████ ████ █████ ██████
Could be true. We don’t know how nonsmokers’ short-term memories stack up against smokers’ short-term memories once those smokers have gone over 8 hours without a cigarette!
d
A regular smoker ████ ███████████ █████ ███████ █ ██████████ ████████ ██████████ ██████ ██████ ██ ██████ ████ █████ █████████ █████████ ██ █ █████████ ██ ████████████ ██████ ██ ███████ ████████ ██████████ ██████ ██████ ██ ███ █████ █████████ █ ██████ ██ █████ ████████
Could be true. The stimulus does nothing to rule out the possibility that the regular smoker described in (D) could experience a boost in short-term memory skills after smoking heavily, even if their short-term memory skills were not superior immediately after one cigarette.
e
The short-term memory ██████ █████████ ██ █ ███████ ██████ ███ ████ ██████ █ █████████ ████ █████ ███ ███ █████████ ████████ ██ █████ █████████ ██ █ ███████ ██████ ███ ███ ████ ██████ █ ██████████
Could be true. We have no information about what happens to smokers’ superior short-term memories during the five hours after their last cigarette—maybe they improve before dropping off later!