Many factors can have an influence on any or all of these stages and therefore affect the accuracy and completeness of an eyewitness account. Once perceived, information is not passively stored in memory and during this retention interval external information influences and changes the witness's memory to such an extent that it dramatically alters their recollections of the original event.
Many factors also influence the retrieval process.
Information may have originally been accurately perceived but may not be accessible at the time of retrieval. The conditions prevailing at the time of information retrieval, what types of questions are asked to obtain information, how these questions are worded and who is asking them, are all examples of important factors that operate during this stage of the memory process and can affect the accuracy and completeness of the eyewitness's account. It is considered to be just as pertinent today as when it was first published. Loftus presents a case against the reliability of the eyewitness by providing detailed descriptions of how memory can be altered by the way a witness is questioned, and how new memories can be implanted and old ones altered in subtle ways. Stress A person's ability to perceive a complex event is affected by the amount of stress that person is experiencing at the time the event is experienced.