What is the test for a brief investigative detention under the Fourth Amendment?

The Fourth Amendment to the United States Constitution prohibits seizures of persons, including brief investigative detentions, when they are "`unreasonable.'" (People v. Souza (1994) 9 Cal.4th 224, 229.) A detention is not "`unreasonable' if the police officer [can] `point to specific and articulable facts which, taken together with rational inferences from those facts,' would warrant the intrusion." (Ibid.) "[T]he temporary detention of a person for the purpose of investigating possible criminal activity may, because it is less intrusive than an arrest, be based on `some objective manifestation' that criminal activity is afoot and that the person to be stopped is engaged in that activity." (Id. at p. 230.) The court must take into account "`the totality of the circumstances' in determining the propriety of an investigative stop or temporary detention." (Ibid.)