A heuristic is sometimes also called a 'rule of thumb'. This phrase is an old one used to describe good procedures for getting an acceptable approximation for quick applications, or sometimes it is used to refer to ways of getting started on a problem to check out the feasibility of an approach that has had success in the past. Algorithms have a probabilistic solution. Sorry, not right. Algorithms are procedures that have a determinate outcome.
Algorithms are precise procedures for calculating a result from specific starting states.
This is another way of saying that an algorithm requires a well defined problem. So, in an magnitude estimation task, subjects are not given time to calculate the answer to, e.g., a math problem, but must very quickly make a guess. Sorry, not right. The problem is a multiplication problem and so subjects try to provide an answer based on starting that process. So, in an magnitude estimation task, subjects are not given time to calculate the answer to, e.g., a math problem, but must very quickly make a guess.