حافظه هیجانی ادراکی است

In two experiments it was investigated which aspects of memory are influenced by emotion. Using a framework proposed by Roediger (American Psychologist 45 (1990) 1043–1056), two dimensions relevant for memory were distinguished the implicit–explicit distinction, and the perceptual versus conceptual distinction. In week 1, subjects viewed a series of slides accompanied with a spoken story in either of the two versions, a neutral version, or a version with an emotional mid-phase. In week 2, memory performance for the slides and story was assessed unexpectedly. A free recall test revealed superior memory in the emotional condition for the story's mid-phase stimuli as compared to the neutral condition, replicating earlier findings. Furthermore, memory performance was assessed using tests that systematically assessed all combinations of implicit versus explicit and perceptual versus conceptual memory. Subjects who had listened to the emotional story had superior perceptual memory, on both implicit and explicit level, compared to those who had listened to the neutral story. Conceptual memory was not superior in the emotional condition. The results suggest that emotion specifically promotes perceptual memory, probably by better encoding of perceptual aspects of emotional experiences. This might be related to the prominent position of perceptual memories in traumatic memory, manifest in intrusions, nightmares and reliving experiences.

The idea that emotional events are better memorized than neutral events is widespread. It is tempting to attribute a functional value to this phenomenon, as emotions signify information that is potentially important for survival. A superior recollection of emotional events might help the organism to better cope with both negative and positive events, i.e. it might help to optimally adapt to the environment. Dozens of animal and human studies have indeed yielded evidence for the idea that emotional events are better memorized than neutral events (e.g., Cahill & McCaugh (1996a) and Cahill & McCaugh (1996b); Christianson, 1992; Roozendaal, 2000). Pharmacological studies have demonstrated that peripheral epinephrine plays a role in this emotion effect, as it stimulates via peripheral β-epinephrine receptors the release of central norepinephrine that stimulates the amygdala, which in turn modulates the storage of memory material ( Cahill, Prins, Weber, & McCaugh, 1994; Cahill & McCaugh, 1998; McCaugh, 1992; van Stegeren, Everaerd, Cahill, McCaugh, & Gooren, 1998, but see O’Carroll, Drysdale, Cahill, Shajahan, & Ebmeier, 1999). Whereas animal research on emotional learning has concentrated on procedural memory (i.e., retention of escape behavior trained in an aversive conditioning paradigm; McGaugh et al., 1993), most human research so far has focused on explicit memory, i.e. has used free recall tests and recognition (multiple choice) tests to assess the retention of stimuli presented during an encoding phase. This is a rather restricted approach, which is problematic for at least two reasons. First, it is well known that memory is not a uniform concept. Memory has many facets, and memory performance depends on the type of memory processes and type of memory material involved. Thus, from a theoretical point of view it is important to investigate various memory processes to get a more complete picture of the influence of emotion on memory. Second, there is one clinical problem for which a better understanding of emotional memory is highly relevant, posttraumatic stress disorder (PTSD). PTSD is thought to be characterized by two seemingly contradictory memory phenomena: a facilitated memory of the traumatic event, as is evident from reliving experiences, intrusions, and nightmares, as well as an inhibited memory, the inability to (voluntary) remember important aspects of the trauma (APA, 1994). The two contrary memory phenomena might be related to specific memory processes, from which it follows that it is important to investigate different memory processes as they relate to emotion. The idea that specific memory processes play a role in producing PTSD symptoms has indeed been put forward. Ehlers and Clark (2000) have proposed that data-driven processing is particularly strong during traumatic experiences, that is the processing of perceptual information, to explain the poor integration of traumatic memories, their perceptual qualities, and their involuntary triggering in PTSD. Ehlers and Clark (2000, p. 331) tend to associate data-driven processing and the resulting perceptual memories with aspects of implicit memory, that is the types of memories that can be involuntary triggered, especially by “perceptual priming”,1 and can influence the subject's behavior without (full) awareness that it is a specific memory. Likewise, Brewin (2001) stipulates two memory systems of relevance for PTSD, one (verbally accessible memory) being voluntary accessible, related to other autobiographical memories, and containing much conceptual information. The other system (situational accessible memory) is assumed to contain information from a “lower level perceptual processing of the traumatic scene” (p. 375), that can be poorly verbally communicated (thus lacks conceptual qualities), and is mainly involuntary triggered by triggers that remind of the trauma. According to these views, situational (perceptual) cues can involuntary trigger specific types of memories of the trauma, especially the reliving type of memories, which can (but not necessarily) become conscious, and may or may not be correctly related to their origin. Thus, these theories state that in PTSD perceptual trauma memories are often triggered in an implicit way (they may become conscious, but this is a secondary effect). Such accounts seem to make a global distinction between implicit–perceptual memories on the one hand, and explicit–conceptual memories on the other hand. Thus, they tend to relate the quality of the stored trauma information (perceptual versus conceptual) to aspects of implicit versus explicit memory, namely the pathway by which the memory is elicited: involuntary and automatically versus voluntary and declarative. The association of implicit memory with type of memory material that has been stored, i.e. with procedural or low level (perceptual, bottom-up) knowledge, is, according to Roediger (1990), not a necessarily one. Roediger (1990) has proposed a framework in which the type of memory retrieval, explicit versus implicit, is completely distinguished from the type of memory material, in which he discerns concepts from data. According to Roediger, new information can initially be processed more on a level directly related to the perceptions (“data-driven”) or more on a conceptual level, that is that the meaning of the information is processed (“conceptually driven”). Initial processing is considered to influence storage and later retrieval, in the sense that information processed on the level of the data is primarily remembered on a similar level, whereas after conceptual processing data-related information is lost, and therefore not stored, so that memories are more of a conceptual quality. Using Roedigers framework, a complete investigation of memory would involve memory tests in each of the four cells of the 2×2 matrix resulting from combining the implicit–explicit distinction with the perceptual versus conceptual distinction (Fig. 1). This contrasts to memory research in which implicit tests are equated with tests of perceptual memory, and explicit tests are equated with conceptual memory. Full-size image (20 K) Fig. 1. Type of retrieval (implicit versus explicit) and type of memory material (data versus concepts) as independent dimensions, and the resulting memory tests. Figure options The present study aimed at investigating the influence of emotion on memory retention. By using memory tests that represent each of the four combinations of the implicit–explicit and the perceptual–conceptual level dichotomies, we intended to investigate emotional memory in all aspects of Roedigers framework. By using the material and instructions originally employed by Cahill and coworkers (Cahill et al., 1994) the present study is not only an attempt to replicate the emotion effect with this experimental paradigm, but also a theoretically and clinically relevant extension.