- The Nature of Memory – Two common memory models are presented. Table 7.1 provides an overview comparing each of these models.
- Memory Models
1. Information Processing Model – The information processing model of memory proposes a computer model to explain how information in memory is processed using the operations of encoding, storage, and retrieval. Encoding gets information into the brain and is similar to a keyboard. Storage retains information like the computer’s hard driveor disk. And, retrieval is the process of getting the information out of memory storage. (See Process Diagram 7.1).
2. Parallel Distributed Processing Model – The PDP or connectionist model of memory views memory as weblike connections among interacting processing units operating simultaneously and more a distributed than a sequential operation.
3. Three-Stage Memory Model: Sensory Memory, Short-term Memory (STM), and
Long-term Memory (LTM)- This model is the most widely used and proposes that memory needs different storage stages to house information for various lengths of time. A flowchart for memory processes (Figure 7.1) includes the three stages: sensory memory, short-term memory (STM), and long-term memory (LTM).
- Sensory Memory - Sensory memory occurs within the senses and very briefly preserves a replica of an image. Visual images (iconic memory) last about 1/4 to 1/2 second and auditory images (echoic memory) up to four seconds. Sensory memory’s capacity is unclear.
- Short-Term Memory - STM is our conscious thoughts or working memory. It can hold about seven (7 + or – 2) items and can store them for about thirty seconds; however, its capacity can be increased by chunking and its duration can be increased by maintenance rehearsal. STM may be viewed as a three-part working memory: Visuospatial Sketchpad, Central Executive, and the Phonological Rehearsal Loop.
- Long-Term Memory - LTM is more permanent and has unlimited capacity. Organization of information improves transfer and retrieval of information, as well as, sleep. LTM is divided into two major systems – explicit/declarative and implicit/nondeclarative procedural memory. Two types of explicit/declarative memory include semantic and episodic memory. Implicit/nondeclarative memory includes procedural skills and simple classical conditioning responses.
Psychology at Work: Improving Long-Term Memory (LTM) -
Strategies for improving LTM involve the processes of encoding storage, and retrieval. (Figure 7.6). Encoding information in LTM may be improved by adding meaning to the information, developing organizations and associations, or relating it to something we already know. Rehearsal also improves encoding for both STM and LTM and includes both maintenance rehearsal and elaborative rehearsal. Retrieval of information from LTM involves the serial-position effect and retrieval cues (Process Diagram 7.1).Three of the most important retrieval cues are recall, recognition, and priming. Paying attention to the retrieval cues of context, mood, and state can also improve memory.
II. Forgetting
- How Quickly Do We Forget? – Hermann Ebbinghaus’ now famous “curve of forgetting” research demonstrated the rapidness at which information is forgotten immediately after learning. However, he also found that relearning can occur more quickly the second time.
- Why Do We Forget? – Five major theories have been offered to explain why forgetting occurs: decay theory, interference theory, motivated forgetting, encoding failure, and retrieval failure. The decay theory proposes that memory deteriorates over time while interference theory suggests forgetting occurs when there is competing information. Retroactive interference occurs when new information interferes with the learning of old information and proactive interference occurs when old learning interferes with the learning of new information. The motivated forgetting theory proposes that we may forget or inhibit the retrieval of information that may be unpleasant, painful, or embarrassing. Encoding failure theory may contribute to information never being encoded from STM to LTM and thus forgotten. Retrieval failures may also contribute to the inability to recall information that is stored in LTM. (Process Diagram 7.3).
Psychology at Work: Key Factors in Forgetting – Four important factors that help prevent forgetting include: (1) the misinformation effect is the distortion of a memory by misleading post-event information, (2) source amnesiais a result of confusion or misattribution regarding the actual occurrence of an event, (3) the sleeper effect is a tendency to initially discount unreliable sources and later consider it trustworthy because the source was forgotten, and (4) the information overload. Forgetting is greatest when students use massed practice or “cramming” rather than distributed practice with breaks in between learning.
Gender and Cultural Diversity: Cultural Differences in Memory and Forgetting –
The work of Ross and Millson (1970) used college students from the United States and
Ghana and discovered that the Ghana students were better at memory testing for themes
in stories presented aloud. Wagner (1982) found that previous experience plays a part in
facilitating memory recognition. It appears that STM is not affected by cultural factors
but that a person’s culture provides background of experience and strategies for
remembering factors specific to that culture.
- Biological Bases of Memory
- How Are Memories Formed? -The biological aspects of memory include neuronal and synaptic changes, hormonal influences, and structures in the brain. Changes in the dendrites occur from repeated reverberating circuits. Hormones produced during stress or excitement, such as epinephrine and cortical play a significant role in memory. These hormones affect areas of the brain structures in the limbic system including the amygdala, hippocampus, cerebral cortex, and other parts of the brain. Hormonal changes during a heightened state of emotions may produce a vivid image surrounding the event as in the phenomenon known as flashbulb memories.
- Where Are Memories Located? – Early memory researchers believed memory was localized, later researchers suggest that memories are distributed throughout the cortex. Current research suggests that memory tends to be both localized and distributed throughout the brain with the right prefrontal cortex and the parahippocampal cortex as the most active regions.
- Biological Causes of Memory Loss – Two biological causes of memory loss including traumatic brain injury (TBI) and Alzheimer’s disease are presented. Memory loss for events that occurred before the injury is called retrograde amnesia and memory loss for events that occur after an injury are called anterograde amnesia. Alzehimer’s disease is a progressive mental deterioration in memory which generally begins between the ages of 45 and 55 and may be primarily genetic.
Research Highlight: Memory and the Criminal Justice System –Research studies
are presented which address two areas of memory problems including the difficulties with eyewitness testimonies and repressed memories. Primarily because of the constructive nature of memory the reliability of eyewitness testimonies are questioned. The area of false versus repressed memories is a hotly contested debate. Because of the constructive element of memory as well as source amnesia, the misinformation effect, and the sleeper effect it is difficult to discern their reliability.
IV.Using Psychology to Improve Our Memory
- Understanding Memory Distortions -The explanation for why memories are often rearranged and distorted can be found in our need for logic, consistency as well as the need for efficiency.
- Tips for Memory Improvement -Eight tips for memory improvement are highlighted: (1) pay attention and reduce interference, (2) use rehearsal techniques –maintenance and elaborative, (3) ) use the encoding specificity principle-context and state, (4) improve your organization, (5)counteract the serial position effect, (6) manage your time – avoid massed practice, (7) employ self-monitoring and overlearning, and (8) use mnemonics – the method of loci, peg-word, substitute word, and word association.
Critical Thinking/Active Learning: Memory and Metacognition - The active learning exercise for this chapter allows students to practice reflective thinking--to "think about thinking"--and to use it to evaluate processes involved in recalling and storing memories.Students are asked to engage in a reflective thinking activity by reflecting on their memories of the first day of their General Psychology course.