6. A system, comprising: at least one computing device that implements one or more services, wherein the one or more services: provide, in connection with navigation of a website by an entity, a collection of security checks to the entity, the collection of security checks including a challenge-response problem based at least in part on evolutionary psychology, cognitive psychology, psycholinguistics, or color psychology; receive a collection of responses comprising at least a first response to a first security check of the collection of security checks and a second response to a second security check of the collection of security checks; calculate, based at least in part on the collection of responses, an aggregate performance score for the entity; determine a reference performance score for the collection of security checks; determine, based at least in part on the aggregate performance score and the reference performance score, information indicative of whether the entity is an automated-agent or a human-user, wherein the information indicates that the entity is human by including one or more incorrect responses of the collection of responses and indicates that the entity is automated by including one or more correct responses of the collection of responses; and perform one or more operations as a result of the information.
11. The system of claim 6 , wherein the reference performance score is included with previous requests and responses associated with the entity, the previous requests and responses being stored as at least part of a profile for the entity.