Why Do We Forget Things?

It is a common occurrence that, despite our best efforts, we occasionally forget certain information. We may overlook wishing someone a happy birthday, fail to remember a person's name, or even forget a significant amount of information during an examination. What accounts for this phenomenon? Furthermore, what strategies can we employ to mitigate it?

Although long-term memory is generally believed to possess an infinite capacity and to endure throughout one’s life, instances of forgetting still arise. If the theory regarding long-term memory holds true, it suggests that the information we fail to recall never actually made it into our memory. In this case, it is not that we have forgotten; rather, the memory simply does not exist. This may be a possibility, but it is not the only explanation. We will explore several theories proposed by psychologists to address the perplexing issue of memory retention.

One such explanation is known as INTERFERENCE. This concept posits that certain factors disrupt our memory, making it more challenging to retrieve information accurately. Interference can be categorized into two types: PROACTIVE and RETROACTIVE. Proactive interference occurs when previously learned information hinders the recall of new information acquired subsequently. For instance, Underwood (1957) discovered that participants exhibited poorer performance on memorization tasks as they were required to memorize an increasing number of word lists. The rationale behind this is that each list learned earlier diminishes the participant's ability to perform well on later lists.

Conversely, RETROACTIVE interference refers to the situation where new information obstructs the recall of older information. This type of interference was examined as early as 1900, when researchers Müller and Pilzecker conducted studies involving participants.

Participants were tasked with memorizing a series of nonsensical syllables and subsequently asked to recall them after a designated retention period. Those who engaged in an additional task during the retention interval exhibited poorer recall performance. This decline in memory retrieval may be attributed to the interference caused by the new information being processed during the interval, which could have disrupted the retention of the nonsensical syllables. Alternatively, the inability to recall may stem from a retrieval failure within long-term memory. While interference typically hinders information from reaching long-term memory by disrupting the rehearsal process, there are various reasons that can explain why we might struggle to retrieve information that we are aware exists in our memory. Difficulties in accessing long-term memory are often linked to the manner in which the information was encoded during the learning phase. The ENCODING SPECIFICITY PRINCIPLE, introduced by Tulving and Thomson in 1973, posits that memories are more easily retrieved when contextual information remains consistent across different time points. Prior to presenting this theory, Tulving, in collaboration with Pearlstone (1966), conducted research to illustrate that memory can be enhanced through the use of additional cues. Participants were instructed to learn 48 words categorized into 12 thematic groups. Each word was presented with its corresponding category, resulting in lists such as: fish-cod, fish-haddock, fruit-apple, fruit-orange. For the recall phase, participants were split into two groups: one group was asked to recall as many words as possible freely, while the other group received prompts in the form of category names. The free-recall group managed to remember an average of 40% of the words, in contrast to the other group.

Participants in the cued-recall group successfully recalled 60% of the words. This indicates that having an additional cue significantly enhances recall, as the same list of words was used and participants were unaware of their group assignment prior to the task. This raises the question: what types of cues exist in everyday life that could influence our memory retrieval? The answer is numerous, which is advantageous in this context. Ethel Abernethy (1940) discovered that students achieve optimal performance on tests when conducted in the same environment where they initially learned the material, particularly in the presence of the original instructor. In contrast, taking a test in a different location with an unfamiliar teacher poses considerable challenges related to context-dependent forgetting, reminiscent of the typical exam setting. Supporting Abernethy’s conclusions, Godden and Baddeley (1975) conducted a notable study with scuba divers, revealing that participants recalled word lists most effectively when asked to do so in the same environment where they had learned the material. When the list was presented underwater, recall was most accurate; however, presenting the list on land did not enhance recall, regardless of the presence of marine life. The significance of location is evident. Additionally, one’s mental state at the time of learning serves as a retrieval cue, a phenomenon referred to as state-dependent forgetting. In the late 1960s, Goodwin et al. (1969) had participants learn a list of words while either sober or under the influence of alcohol. The participants in the drinking condition were instructed to consume a specific amount of alcohol.

The participants were approximately three times over the legal limit for alcohol consumption, which raises the question of whether the researchers arranged for their transportation home. After a 24-hour period, the participants were asked to remember a list of words. Half of each group returned to the same level of intoxication they had experienced during the initial learning phase, while the other half either abstained from alcohol or consumed it in excess, depending on their previous behavior. It is anticipated that sober individuals would demonstrate the highest recall accuracy when also sober during the recall phase, and this expectation is confirmed. However, an unexpected finding emerged: intoxicated participants were able to recall nearly as many words as their sober peers, provided they were intoxicated again at the time of recall. Both groups encountered difficulties in recalling the words when in a different state than when they initially learned them. Similar phenomena have been observed with caffeine and overall mood; when individuals are in a positive emotional state, they tend to recall happy memories, whereas negative emotions can obscure those same memories, making them seem inaccessible. This phenomenon is known as state-dependent forgetting.