Does it take longer to choose among more alternatives?
From an optimization-view of human decision making it makes sense that choosing among more alternatives would take longer, simply because there are more alternatives to evaluate before deciding. If humans use simple rules of thumb or use satificing rather than maximizing strategies, it is far fram clear that choosing among more options will take longer.
To examine the question empirically, one could add a real life choice situation towards the end of a survey, for example by having the respondents choose among several options for e.g. charity donations-By randomizignthe number of options displayed data on time to choose among N alternatives for N ranging from 2 to around 25 (or even higher) can be easily collected.