What did you eat for dinner one week ago? What is your name? Who you are? When answering these questions, we are always referring to our memory, where information is actively encoded, stored and retrieved in the brain. Without memory, people are unable to learn, accumulate experiences or expand survival skills and outreach abilities to operate, whether in the present or not even to think about the future. As memories are playing such a vital role in human life, psychologists have been actively researching this area for decades.
1. Memory with meaning is better remembered.
Memories are better kept with semantic encoding, where a memory storage system that involves elaborating on the meaning of the information. Elaboration on meaning will create a stronger link between active neurons and deepens the level of information processing, hence, the strength and duration of the memory increased.
!! Additionally, repeated rehearsing may aid the retention of information in memory.
2. Some memory only last for a fraction of seconds.
Sensory memory systems from sensory nervous systems (e.g., eye, ears, nose) include Iconic memory, Echoic memory and Haptic memory. The old information received will be pushed by new information received due to occurrence of masking. Therefore, Iconic Memory from visual sensory systems can only last for around 1-2 second; Echoic Memory from what a person has heard can last for up to 3-4 seconds; Haptic Memory which involves the memory of touch can last around 2 seconds according to George Sperling’s study.
A loss of vision is associated with changes of the brain facilitated by synaptic plasticity, where a process enables experience-dependent adaptation, learning and memory. Researchers from Bochum found that after the emergence of blindness, there are changes in the density of neurotransmitter receptors that are crucial for synaptic plasticity. As the synaptic plasticity in hippocampus becomes more impaired, the spatial memory will be affected in subsequent months.
A human mind can create, exaggerate, or re-invent a memory. In the experiment of Loftus and Palmer to investigate the distortion of memory, participants were randomly assigned to watch different videos of a car accident. The participants filled out a survey asking about “How fast the cars were going when they smashed into each other?” by replacing the term “smashed” with other verbs including “bumped”, “collided”, “hit” or “contacted” to reactivate participants’ memories. Participants estimated collision in higher speed when researchers used a harsher word to ask the question. The manipulation of the properties of reactivation can influence memories are once reconfirmed.
Video: Brain game car crash experiment (Source: Youtube)
5. Hot flashes impair memory performance.
Previous studies have shown that women undergo menopause with vasomotor symptoms including hot flashes will experience a decline in memory for verbal materials such as words and stories. Functional Magnetic Resonance Imaging (fMRI) reveals that physiologic hot flashes are associated with the decrease of memory performance and alteration of brain function, specifically in the hippocampus and prefrontal cortex.
6. The capacity of short-term memory is only about 7 plus or minus two bits of information.
The ability of selective attention enables humans to focus on only one stimulus from among all sensory input in a short term memory system, yet the capacity of short-term memory is usually only about seven plus or minus two item bits of information according to Miller’s experiment. Sensory information that is transferred into short term memory may hold for up to 30 second and longer through maintaining rehearsal.
7.Sleep deprivation may lead to memory loss
Sleeping is initially known as a memory enhancer through protecting memories from interfering stimuli. Besides, sleep also plays an active role in enabling different types of memories to undergo consolidation. Sleeping is composed of 5 stages: Very Light Sleep, Light Sleep, Slow Wave Sleep (SWS), Delta Sleep and Rapid Eye Movement (REM).
During Slow Wave Sleep (SWS), declarative memory (memory that can be consciously recalled) is encoded into a temporary store in the anterior part of the hippocampus, then repeatedly reactivated, and redistributed to long term storage in the cortex. In contrast, Rapid Eye Movement (REM) while sleeping is associated with the consolidation of procedural memory, unconscious memory of skills and how to do or use things, as well as movement of the body. Hence, sleep deprivation is significantly associated with a decrease in memory.
Many research found that older adults are associated with deterioration of memory retention due to shrinkage of the brain. This leads to the decrease in function of vital brain structures involved in memory such as the hippocampus. However, new studies by Maede discovered that older adults who take up drawing can improve on their memory, even though they are not good at it (Pedersen, 2018). Besides, Maede also suggested that drawing can act as a therapeutic intervention to help dementia patients hold on to valuable episodic memories.
Hubbard, N. A., Hutchison, J. L., Turner, M., Montroy, J., Bowles, R. P., & Rypma, B. (2016). Depressive thoughts limit working memory capacity in dysphoria. Cognition & emotion, 30(2), 193–209. https://doi.org/10.1080/02699931.2014.991694
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Yee Teng is an intern at Be❦Live in Psychology. She is currently pursuing her Degree in Psychology at HELP University. Apart from psychology, Yee Teng is also interested in investment, passionate in helping people and doing creative works.