Encoding and storage are necessary to acquire and retain information. But the crucial process in remembering is retrieval, without which we could not access our memories. Unless we retrieve an experience, we do not really remember it. In the broadest sense, retrieval refers to the use of stored information.
For many years, psychologists considered memory retrieval to be the deliberate recollection of facts or past experiences. However, in the early 1980s psychologists began to realize that people can be influenced by past experiences without any awareness that they are remembering. For example, a series of experiments showed that brain-damaged amnesic patients who lose certain types of memory function were influenced by previously viewed information even though they had no conscious memory of having seen the information before. Based on these and other findings, psychologists now distinguish two main classes of retrieval processes: explicit memory and implicit memory.
Explicit memory refers to the deliberate, conscious recollection of facts and past experiences. If someone asked you to recall everything you did yesterday, this task would require explicit memory processes. There are two basic types of explicit memory tests: recall tests and recognition tests.
In recall tests, people are asked to retrieve memories without the benefit of any hints or cues. A request to remember everything that happened to you yesterday or to recollect all the words in a list you just heard would be an example of a recall test. Suppose you were briefly shown a series of words: cow, prize, road, gem, hobby, string, weather. A recall test would require you to write down or say as many of the words as you could. If you were instructed to recall the words in any order, the test would be one of free recall. If you were directed to recall the words in the order they were presented, the test would one of serial recall or ordered recall. Another type of test is cued recall, in which people are given cues or prompts designed to aid recall. Using the above list as an example, a cued recall test might ask, “What word on the list was related to car?” In school, tests that require an essay or fill-in-the-blank response are examples of recall tests. All recall tests require people to explicitly retrieve events from memory.
Recognition tests require people to examine a list of items and identify those they have seen before, or to determine whether they have seen a single item before. Multiple-choice and true-false exams are types of recognition tests. For example, a recognition test on the list of words above might ask, “Which of the following words appeared on the list? (a) plant (b) driver (c) string (d) radio.” People can often recognize items that they cannot recall. You have probably had the experience of not being able to answer a question but then recognizing an answer as correct when someone else supplies it. Likewise, adults shown yearbook pictures of their high-school classmates often have difficulty recalling the classmates’ names, but they can easily pick the classmates’ names out of a list.
In some cases, recall can be better than recognition. For example, if asked, “Do you know a famous person named Cooper?” you might answer “no.” However, given the cue “James Fenimore,” you might recall American writer James Fenimore Cooper, even though you did not recognize the surname by itself.