test the effect of caffeine on memory, 1 group partic is given coffee, another group isn't. They're both given the same list of words to recall
Advantages
no order effects: partic only does one condition = performance less likely to improve due to practice/get worse due to boredom
demand characteristics: less likely to occur, partic less likely to guess aim as they only take part in one condition
Disadvantages
particvariables: may differ between groups = become confounding if left uncontrolled
more partic needed = lower ecological validity
Ways to deal with disadvantages
randomly allocate to conditions: even distribution of participant variables, done by names in hat being drawn so every other partic goes to condition 1/2
