2. (20 points) The following are examples of different types of human memory. For each pair in the lists A-D, compare the two types of memory by mentioning, for example, their differences in function and structure.
A. Sensory memory vs. working memory
B. Iconic memory vs. echoic memory
C. Short-term memory vs. long-term memory
D. Explicit memory vs. implicit memory
ANSWER by Umer Fareed
Sensory Memory: The sensory memory contains an exact copy of what a person sees (visual) or hears (auditory). It only lasts for a few seconds. Some opinions are that it lasts for only 300 milliseconds. It has unlimited capacity. Its structure is assumed to be built on stimulus persistence (something that looks like physical stimulus stays present even after stimulus is no longer present) and information persistence (information extracted from the presented stimulus after it’s removal). The ability to look at a stimulus and remember what it looked like with just a second of observation, or memorization, is an example of sensory memory.
Working Memory: The working memory is defined to have a dedicated system that maintains and stores information in the short term, and that this system underlies human thought processes. Stored information decays quickly unless actively rehearsed. Current views of working memory involve a central executive, the phonological loop and the visuo-spatial sketchpad; and the multimodal episodic buffer. The central executive passes information to the three component processes: the phonological loop, the visuo-spatial sketchpad, and the episodic buffer. The phonological loop stores auditory information by silently rehearsing sounds or words in a continuous loop; the articulatory process (the "inner voice") continuously "speaks" the words to the phonological store (the "inner ear"). The visuo-spatial sketchpad stores visual and spatial information. It is engaged when performing spatial tasks (such as judging distances) or visual ones (such as counting the windows on a house or imagining images). The episodic buffer is dedicated to linking information across domains to form integrated units of visual, spatial, and verbal information and chronological ordering (e.g., the memory of a story or a movie scene).
Iconic Memory: Iconic memory is a type of sensory memory named by George Sperling in 1960. According to Sperling, it lasts only approximately 250 ms after the offset of a display and has a rapidly decaying behavior. Iconic memory is thought to be the sensory store for vision. Ulric Neisser (1967) proposed the idea that iconic memory preserves an exact duplicate of the image falling on the retina. It contains all the sensory information available from the retina of the eye. Current concepts of iconic memory have refined Sperling’s original formulation; now iconic memory is viewed as a short-term sensory (visual) buffer, allowing time for sensory information to be recoded in a more permanent, categorical manner. Iconic memories are fragile, decay rapidly, and are unable to be actively maintained.
Echoic Memory: It is the auditory version of sensory memory; which is believed to be a brief mental echo that continues to sound after auditory stimuli has been heard. The idea behind echoic memory is that auditory information may persist in the form of an echo that can be attended to after the original stimulus is removed. According to Neisser (1967), echoic memory lasts for only one or two seconds. In the echoic memory, the inner ear converts sounds train of nerve impulses that represent the frequency and amplitude of individual acoustic vibrations. Due to its short span, echoic memory is a type of sensory memory as the echoic memories are temporal and last only for a brief period of time. For example, when given two different sound tones, listeners were unable to match two tones after a very short delay time (300 milliseconds) but were able to correctly match when there was no delay between the tones. Echoic memory can be expanded if it is repeated in the phonological loop which rehearses verbal information in order to keep it in short term memory.
Short-term Memory: Short-term memory (STM) refers to memory processes that retain information only temporarily, until information is either forgotten or becomes incorporated into a more stable, potentially permanent long-term store. Estimates of short-term memory capacity vary from about 3 or 4 elements (i.e., words, digits, or letters) to about 9 elements: a commonly cited capacity is 7±2 elements. The information held in short-term memory may be either recently processed sensory input or items recently retrieved from long-term memory.According to Miller (1956), capacity of short-term memory is limited. Duration of short-term memory is brief (Peterson and Peterson, 1959). Most definitions of short-term memory limit the duration of storage to less than a minute; no more than about 30 seconds, and in some models as little as 2 seconds. Without attention and rehearsal, information is lost rapidly from STM. In order to overcome the limitation of short-term memory, and retain information for longer, information must be periodically repeated, or rehearsed — either by articulating it out loud, or by mentally simulating such articulation. In this way, the information will re-enter the short-term store and be retained for a further period. When several elements (such as digits, words, or pictures) are held in short term memory simultaneously, their representations compete with each other for recall, or degrade each other. Thereby, new content gradually pushes out older content, unless the older content is actively protected against interference by rehearsal or by directing attention to it.
Long-term Memory: Long-term memory (LTM) is memory that can last as little as a few days or as long as decades. It differs structurally and functionally from short-term memory. As long-term memory is subject to fading in the natural forgetting process, several recalls/retrievals of memory may be needed for long-term memories to last for years, dependent also on the depth of processing. Individual retrievals can take place in increasing intervals in accordance with the principle of spaced repetition. This can happen quite naturally through reflection or deliberate recall (a.k.a. recapitulation or recollection), often dependent on the perceived importance of the material. The brain stores long term information by growing additional synapses between neurons. Since the brain has approximately 1015 synapses, one can argue that brain has a maximum capacity of about 100 TByte, possibly more if one synapse can store more than 1 bit of information. By no means do humans store that much information. Experiments in the mid 1980s showed that humans can store only 1-2 bits/second in their long term memory. The cumulative amount of data stored in the brain over a 70 year lifetime is therefore only in the order of 125 Mbyte. Studies undertaken by Bahrick predicted that long term memory can indeed remember certain information for almost a lifetime. However factors can in fact reduce or extinguish information completely. For Example, childhood amnesia is a factor effecting long term memories duration, there are very few people who can remember information or events before the age of 3 or 4.
Explicit Memory: Explicit memory is the memory with awareness. It is the conscious, intentional recollection of previous experiences and information. We use explicit memory throughout the day, such as remembering the time of an appointment or recollecting an event from years ago. Remembering a specific driving lesson is an example of explicit memory. Explicit memory depends on conceptually driven, top-down processing, in which a subject reorganizes the data to store it. The subject makes associations with previously related stimuli or experiences. The later recall of information is thus greatly influenced by the way in which the information was originally processed. There are two kinds of explicit memory: Episodic memory, also called autobiographical memory, consists of the recollection of singular events in the life of a person. It is the memory of life experiences centered on yourself. Second one is Semantic memory that consists of all explicit memory that is not autobiographical. Examples of semantic memory are knowledge of historical events and figures; the ability to recognize friends and acquaintances.
Implicit Memory: It is often referred to as memory without awareness. The key difference with respect to explicit memory is that at the time of test, subjects are unaware that the task they are performing is related to a particular study. Improving your driving skills during the driving lesson is an example of implicit memory. In daily life, people rely on implicit memory everyday in the form of procedural memory, the type of memory that allows people to remember how to tie their shoes or ride a bicycle without consciously thinking about these activities. Implicit memory is distinct from explicit memory and exists as its own entity, with its own processes.
3. (20 points) Explain the embedded processes model of immediate memory. How does this model differ from Baddeley’s working memory? What are the strengths and weaknesses of the model?
ANSWER by Vengertsev Dmitry
Embedded process model of immediate memory:
Embedded processes model consists of central executive, long-term memory, active memory (subset of memory in a temporarily heightened state of activation), and the focus of attention, which are represented in Figure 2. It involves all information accessible for a task: memory in the focus of attention; memory out of the focus but nevertheless temporarily activated; and inactive elements of memory with pertinent retrieval cues. Active memory is a subset of long-term memory and the focus of attention is a subset of the active memory. The direction of the focus of attention is controlled by the central executive.
In embedded processes model some of the necessary information may be in the focus of attention, some may be in an especially active state, ready to enter the focus as needed, and some may simply have the appropriate contextual coding in long-term memory that allows it to be made available quickly.
It differs from Baddely’s working memory in following respects
1) It does not divide immediate memory into separate subsystems.
2) It specifically include a long term memory contribution – working memory is essentially activates long-term memory, that is long-term memory plays important role in short-term memory task. Baddely’s model allowed only phonological loop to play major role.
The greatest advantage of embedded processes model as was mentioned before it introduces long-term memory. It provided demonstration of long-term memory effects, such as memory span (the number of items that can be immediately recalled in order).
Another advantage of embedded processes model is that it predicts that output time will have an effect on measures of span.
One of the weaknesses about embedded processes model is the usage of the term activation. To code information in some cases nervous system uses a change in the rate of firing, rather than activity versus no activity. Another problem relates to assumption of deactivation. In memory studies idea of usage decay in connectionist network was criticized and then rejected. In memory, information appears lost over time but time should not be given causal role.
4. (20 points) Memory can be viewed as a process rather than a structure. Explain the theory of transfer appropriate processing (TAP). In what aspects is this theory different from the levels of processing view? What kind of data can TAP explain best? Explain also the relationship to the encoding specificity principle of Tulving.
ANSWER by Subhojit Chakladar
It states that memory performance is not only determined by the depth of processing but the relationship between how information is initially encoded and how it is later retrieved. The performance is best when processes engaged in during encoding match those engaged in during retrieval. For example, if the learning uses a shallow process (which involves relatively low depth of processing of the given information) then a retrieval task that involves shallow processing gives the best performance. Thus a match between the information enters the system (the brain or memory) and leaves the system (how the subject uses the stored information), leads to better performance than when they are mismatched. No one type of process is good for all tests.
The level of processing takes a different view. It states that recall of a stimulus is a function of the depth of processing. The more deeply a given information is analyzed (determined how it is connected to preexisting memory, time spent in analyzing it, the cognitive effort), the more durable it is in the memory. On the other hand shallow processing using just superficial properties of the presented information leads to a fragile memory test that is susceptible to rapid decay. Thus according to level of processing, any information that was not analyzed deeply will not be remembered well. Of course this is not true in all cases. Though a more detailed analysis is better for remembering many things, there can be deviations. For example, if we see a certain thing for a very short time, we may forget about it temporarily but a certain suitable cue (that may or may not be directly related to the previous thing) may elicit the memory of that object, even though it was not analyzed deeply. Clearly, this contradicts the level of processing view of memory. On the other hand, transfer appropriate processing tells that the memory is dependent of the match between the encoding and the retrieval mechanism. A match between the two in the above case will lead information not deeply analyzed to be remembered. Thus the difference between transfer appropriate processing and level of processing view is the dependence of memory on the match between encoding and retrieval process. While the former states that memory performance is dependent on them, the latter states that it is independent of them.