¶ … Pleasant vs. Unpleasant Stimuli on Free Recall Memory is a mental process where information is encoded, stored, and then retrieved at sometime in the future. There is the great deal of research attempting to ascertain what particular factors associated with the stimuli to be remembered and with the emotional state of the learner either increase or decrease the amount of material recalled during learning trials. One factor that has been manipulated is whether or not the material to be learned is judged to consist of either pleasant or unpleasant stimuli. Of course this judgment is often an individual one, but the researchers have attempted to use stimuli that are normally judged to be either pleasant or unpleasant or have been normed on these attributes to determine the effects of pleasantness on recall for material to be learned. The current study attempted to replicate the findings that recall material is greater when the content of the material is associated as being pleasant vs. material that is associated as being emotionally unpleasant in a sample of college students. The findings of this study are consistent with the overall findings in the research. The results are discussed in the context of the methodology used, inferences that can be made from the findings, how the current findings suggest that individuals should approach learning situations, and directions for future research.

Memory refers to a mental process where information is encoded, stored, and retrieved for use (Atkinson & Shiffrin, 1968). The early stage models of memory conceptualized a process beginning at the sensory stage (with a very short duration large capacity) moving into short -- term memory (with a limited duration and limited capacity), and humility in long-term storage (typically believed to be unlimited in both duration and capacity; Reisberg, & Snavely, 2010). While these early stage models have been expanded, their basic premises remain valid (Christianson, 2014). One important issue that has often surfaced in the research as that the process of memory is not, contrary to what many believe, like a tape recorder that accurately records events as they are presented in the environment. Instead, our recollection of events is pliable and subject to a number of influences (e.g., Loftus, 1979).

In order for people to form memories, information must transverse through several phases/stages (Christianson, 2014). Transitioning from one stage to another requires a different process depending on the stage. For example, in order to single out relevant information in sensory storage one must pay attention to it; in order to retain information in short -- term memory one must use some form of rehearsal; and in order to transfer information into long-term storage one must use some form of encoding strategy that might involve rehearsing or conceptualizing information (Domjain, 2004). While sensory storage is considered to have a large capacity and is specific to the sensory domain (e.g., sight, sound, etc.), short-term memory has a much more limited capacity commonly cited as "7 ± 2" chunks of information (Miller, 1956). More recent conceptualizations of short-term memory include the model of working memory Baddeley & Hitch, 1975). While the terms working memory and short-term memory are often used interchangeably, working memory refers to the structures and processes that occur in short-term memory designed to temporarily store and manipulate information. Baddeley and Hitch (1975) refer to these processes as the visuospatial sketchpad (for images and other visual information), a phonological loop (for use with verbally mediated information), and an executive control system that manages these and coordinates the processes when more than one system must be used simultaneously. In addition, the major components of the visuospatial sketchpad and phonological loop also have subdivisions making the concept of working memory quite complex. Many of the stimuli that we attempt to encode have both visual and language-based features to them and therefore tax all aspects of working memory (Christianson, 2014).

Long-term memory is also no longer considered to be a singular construct (Christianson, 2014). The first major distinction that has been made in long-term memory is whether the memories in this type of storage are consciously accessible, that there is a need for conscious recollection or recall when reproducing these memories (in other words these memories would be part of the controlled processes in a dual-process model of cognition that divides cognitive processes based on several attributes such as their speed, access to consciousness, etc.; Christianson, 2014). Memories that are consciously accessible have been termed declarative or explicit memory (Christianson, 2014). Memories that are not consciously accessible have been termed non- -- declarative memory or implicit memory (this division would consist of automatic...

Declarative and non-declarative memory are further divided into several subdivisions.
In order to become registered in long -- term memory information must first be retained in short-term or working memory. Because short-term memory has a limited capacity and duration one can adopt different strategies in order to maximize its potential. Likewise, certain forms of information may further limit the capacity of short-term memory. There are several different hypotheses as to why this is so. One popular hypothesis is that because short-term memory has limited resources, vague or less salient types of information are not activated as strongly as more concrete and salient types of information are (Just & Carpenter, 1992). In addition, it is been hypothesized that processes such as interference and decay are especially prominent with regard to working memory due to its well -- defined limited capacity (Towse, Hitch, & Hutton, 2000). Thus, information that can be conceptualized or tied to past experience has an automatic advantage when one is attempting to retain it in short -- term memory. Very abstract concepts or concepts that are not readily activated by both the visuospatial sketch pad and the phonological loop in working memory should even further limit the capacity and duration of short-term memory (Paap, Newsome, McDonald, & Schvaneveldt, 1982). Thus, understanding how different types of stimuli are encoded in retain in memory can offer a great deal of insight into the memory process itself. One of the areas of this research involves how the effects of emotionally charged stimuli or personal judgments regarding whether the stimuli is likeable (pleasant or unpleasant) affect recall.

From an evolutionary perspective, it would appear to be adaptive for memory for stimuli perceived as pleasing or pleasant to be enhanced, because these stimuli are often more important regarding survival and reproduction than are unpleasant or neutral stimuli (e.., food, potential partners, etc.). Research also suggests that stimuli that produce judgments such as being pleasant or unpleasant move through the brain in parallel with systems that are allocated towards attention (Christianson, 2014). Since attention is not a global process it may well be that the arousal associated with these judgments helps individuals maintain a readiness to respond to situations. There are other factors that can confound this relationship, such as age; however, emotionally charged events and affective judgments of stimuli being either pleasant or unpleasant are remembered better than neutral ones (Christianson, 2014).

It also appears that memories are treated differently in the brain when associated by pleasant emotions or unpleasant emotions or judgments regarding the pleasantness of stimuli (Christianson, 2014) such that information in memory is retained differently depending on whether it is associated as being pleasant or unpleasant (Christianson, 2014). Overall it appears that stimuli judged to be pleasant (or positive memories) contain more contextual details which help them to be encoded, consolidated, and stored in memory more efficiently than do negative (unpleasant) and neutral stimuli (Christianson, 2014).

For example, Bradley, Greenwald, Petry, and Lang (1992) tested 89 students' recall of 60 pictures that were either rated as moderately or highly pleasant or unpleasant. The nature of the pictures was rated on such qualities as valence and arousal. A free recall test was a performed immediately following the presentation of the 60 pictures and 59 of the 89 students were contacted again a year later and given a delayed recall test. Results indicated that in the free recall condition the pictures rated as either moderately or highly pleasant or recall with greater frequency than pictures rated as either moderately or highly unpleasant. However, following a year delay there was an interaction such that the moderately pleasant pictures were recalled only slightly more often than the moderately unpleasant pictures, whereas pictures rated as highly unpleasant were recalled slightly more often than pictures rated as highly pleasant. The differences between the two (pleasant and unpleasant) were not significant in either the moderately or highly pleasant/unpleasant conditions during the long-term recall conditions; however in the immediate recall condition these differences were highly significant, suggesting that the effect of emotional valence may only be important during encoding.

Recognition memory differs from free recall in that during recognition one does not need to actually retrieve stored information but only associate it with past experience (Christianson, 2014). Researchers have tested whether emotional valence affects recognition memory as well. Fernandez-Rey and Redondo (2007) randomly presented 193 volunteers (137…