Working Memory Discussion and Design Review May 5, 2015
What is working memory? Working memory is the ability to retain and manage information in the mind over short periods of time and apply it in current thinking. (Gathercole & Alloway, 2007)It is commonly referred to as the workbench of the mind, as it is the space in which the brain manipulates information in order to understand, make decisions, and solve problems. (Holmes, 2012) Baddeley (1992) defined working memory as “a brain system that provides temporary storage and manipulation of the information necessary for such complex cognitive tasks as language comprehension, learning, and reasoning” (Baddeley, 1992 ). Working memory operates in tandem in long term memory by retrieving pertinent information previously stored that relate to the task at hand. This allows for the mind to interpret the stimuli, while also considering new information and developing new insights. The outcome of this thinking is then encoded and returned to long term memory. (Baddeley & Logie, 1999) In 1974 Baddeley and Hitch introduced the idea that working memory has three main components: the phonological loop, the visuo-spatial working memory, and the central executive. (Baddeley & Hitch, 1974) The first component is the phonological loop. This element is made up of two parts; the phonological store, a short term storage system intended to hold data that comprises words, and the sub-vocal rehearsal process, used to store words and sounds that may be rehearsed. The second component of working memory proposed by Baddeley and Hitch (1974) , the visuo-spatial working memory is known as “the work pad” of the mind. This component enables humans to visualize ideas through the mind’s eye. The third and final component is the central executive. This element directs the use of the information stored in both the phonological loop and the visuo-spatial memory. (Baddeley & Hitch, 1974) Working memory is characterized by three primary traits; limited capacity, limited duration, and high volatility. Emotions such as anxiety and motivation also impact the function of working memory. In the following writing, each of these elements will be explored, along with the design implications that arise in order to leverage these signature traits and influencers of working memory with examples from Intuit Turbo Tax Free online edition. Capacity The first characteristic of working memory purports that working memory is a limited capacity storing system. It serves as the restricted space between the infinite possibilities of perceived stimuli in the world, and the infinite capacity storing system that personifies long term memory. (Cowan, 2001) Working memory is often referred to as a bottleneck due to its strict limitations of information storage. In 1956, the research of George Miller proposed that most humans can store roughly seven chunks of information in working memory at any given time. (Miller, 1956) Since this finding, further research has revealed that the capacity for retaining information for immediate use in working memory is actually much smaller than seven, and remains closer to three or four separate pieces of information at one time. (Cowan N. , 2012 ) One aspect of George Miller’s research that has been validated is the concept of chunking. Chunking is a form of human pattern recognition by which humans group together bits of information based on similarity in order to increase their recognition in memory. (Miller, 1956) Chunking allows for more information to be stored in working memory at one time. This relates to how the working
memory of an expert functions within the context of their chosen domain. One study revealed that “experts do not have a larger working memory capacity than non-experts. Instead, their memory is more detailed.” (Scolari, Vogel, & AWH, 2008) In other words, experts do not a large capacity, but they do have a broader understanding of a given area, which allows them to connect information on a larger scale increasing the amount of information held in working memory. Attention is the intentional selection of specific information at the expense of other information (Pashler, 1999). Attention leverages the limited capacity of working memory to focus on the most important stimuli present. As Scolari, Vogel and Awh note selective attention, “emphasizes the efficient encoding of relevant targets in spite of a potentially overwhelming quantity of sensory information.” (Scolari, Vogel, & AWH, 2008).The function of attention leverages the limited capacity of working memory to increase efficiency of information processed. The concept of chunking, mentioned earlier in this writing also relates to attention. As Bor proposes “In terms of grand purpose, chunking can be seen as a similar mechanism to attention: Both processes are concerned with compressing an unwieldy dataset into those small nuggets of meaning that are particularly salient. But while chunking is a marvelous complement to attention, chunking diverges from its counterpart in focusing on the compression of conscious data according to its inherent structure or the way it relates to our preexisting memories.” (Bor, 2012) The design implications of the restricted capacity of working memory are reflected in the work requirements imposed on the user. The amount of information required or offered up should never exceed the capacity of working memory, which research has shown is three to four chunks of unrelated information at one time. (Cowan N. , 2001)If greater work is demanded than the user has to give, anxiety and frustration will set in and create a negative experience. Turbo Tax does an excellent job of this by breaking information up into smaller bits of information so the user can focus on the optimal amount of information at one time. In the example below this is shown by placing only the pertinent information on the screen.
Special considerations should also be taken into account for user groups with limitations in the working memory. An example of this would be when designing for the elderly population as working memory capacity decreases with age. (Schneider-Garces, Gordon, & Brumback-Peltz, 2010)There are also user groups that have limited working memory capacity due to physiological issues such as ADHD. In these user groups with increased limitations, it is important to understand the restraints of the working memory capacity of these populations and ensure the cognitive load requirements do not exceed the capacity. Carrying information over whenever possible also assists in the augmenting the limited capacity of working memory. Duration
The next defining element of working memory is it’s limited duration. Duration refers to the amount of time working memory can retain information in an active readily available state. (Mastin, 2010) Atkinson and Shiffrin propose that the maximum interval for storage of information within working memory is twenty to thirty seconds. (Atkinson & Shiffrin, 1968) Some researchers propose that this duration is even less, clocking in at around eighteen seconds. (Peterson & Peterson, 1959) The limited duration of storage is also influenced by the entrance of unintended and irrelevant thoughts drifting into working memory. This is referred to as interference. Interference occurs when the information being held by working memory activates information that is stored in long term memory. (Tomlinson, Huber, Rieth, & Davelaar, 2009) This prior knowledge drifts into working memory, limiting the amount of space available for the new information to be stored. The limited duration of working memory can be augmented in design by working with it’s nature in order to create a pleasant experience. The first implication is that users should never have to carry information over from one area of an interface to another. The limited ability to store information is not conducive to a design that requires this workload from users. This can be leveraged by carrying information over automatically whenever possible. This is exemplified in Turbo Taxes’ interface, where the name and date of birth is carried over from one previous form in the site to another.
Li’s Interference model (1999) proposes that elderly users are more likely to experience interference in comparison to younger users. (Holmes, 2012) Furthermore, Hasher and Zacks (1988) found that interference is more likely to occur within the elderly population when prompted with external information, as opposed to information from their own memory due to a slower processing time of the external information, allowing irrelevant thoughts to creep in. (Hasher & Zacks, 1988)These finding should be taken account when designing for these specific user groups. Turbotax leveraged this within the interface by providing two options, “guide me” which provides a thorough step by step instruction and prompts, or jump to a full list which allows the user to rely on their own knowledge of the process to make decisions.
Volatility The third trait that characterizes working memory is volatility. Volatility refers to the reality that once information is lost from working memory, it is gone forever. The volatility of working memory could be considered a product of the two aforementioned traits, limited capacity, and limited duration. The limited amount of storage, in combination with the restricted amount of time information can be held creates an environment where information can easily be lost. There are several ways information can be lost from working memory. One way is interference, the entrance of irrelevant thoughts into working memory, which has been discussed in depth in a previous section. Another way is from interruption. As Clapp and Gazzaley ( 2012) note “Interruption by external interference involves intervening stimuli that are purposefully attended to as an aspect of a secondary task (e.g., a phone call while holding something in mind). An interruption requires a reallocation of cognitive resources, as well as processes involved in reactivating the disrupted representation afterwards.” (Clapp & Gazzaley, 2012). This reallocation of cognitive resources can cause information to be lost forever. Despite working memory’s volatility, information can be recalled based on a few cognitive practices. After the sensory system receives stimuli from the environment, perceptual processing begins. Working memory is the space where these stimuli start to be encoded by the mind, phonetically, visually, or semantically. Working memory is volatile because the only way to retain the information held in working memory is to rehearse and repeat until the information is worn into long term memory. Decay occurs when information has not been rehearsed and the capacity to recall decreases. Frequency of repetition increases the recall and retention rate. This is why experts have a quicker response time, as well as the ability to recall information in larger chunks as mentioned previously. Treisman’s theory of attenuation proposes that selective attention can reduce the processing of unattended stimuli based on the amount of capacity available in working memory. (McLeod, 2008 )This relates to volatility because the physical characteristics of unattended input are remembered over their meaning, with the meaning being lost or not even considered in working memory and thus absent from the long term memory. Volatility should be considered in the design of products and interfaces when evaluating the environment in which the product is being used. Is the user in an environment that sustains frequent interruptions such as a hospital setting? The designer must consider the frequency and duration of possible interruptions from the environment. Turbo tax does a nice job of understanding the environment in which users interact with their product, in the home most likely after work, with several distractions. Due to this the system is broken down is smaller parts with several stopping and options for the user to leave and come back if necessary. The information is predominately procured through prompts so the risk losing information is made obsolete.
Knowledge processes should be enabled through the design, for example automating processes wherever possible, and changing long processes to shorter routines. Staged learning may also be considered in complex systems to ensure that basic concepts are accepted into long term memory before being built upon by more complex interactions. Motivation Motivation is an emotional element that has been demonstrated to impact working memory. Motivation as defined by Pintrich and Schunk (1996) is "the process by which goal-directed behavior is instigated and sustained." (Pintrich & Schunk, 1996) Through this definition, motivation can be understood in relation to working memory as the conscious allocation of working memory resources through selective attention in order to accomplish a goal. (Brooks & Shell, 2012) The higher the level of motivation, the more working memory resource is intentionally allotted towards the given task. Motivation not only effects both which stimuli receives the most attention resource, but also the depth of learning allocated to understand it. Highly motivated individuals are less likely to engage in mindless behavior, and more apt to sustain mindful learning behavior. This is an example of how motivation facilitates a more complete use of working memory resources. Motivation has also been shown to affect several other areas aside from selective attention including encoding of a stimuli and active maintenance. (Brooks & Shell, 2012) Webster’s dictionary defines motivation as, “the reason or reasons one has for acting a certain way” (Merriam-Webster, 2014 )From this definition, we can view motivation as it relates to the value a user derives from the interaction of a product or service or from engagement in an activity. This is relevant in the design of interfaces to ensure that the value received by the user is understood and always outweighs the investment cost to receive it. Products can be designed to create a sense of motivation or pleasure in order to engage the user. An example of this would be performance validation built into a system, such as within a reward when completing a level in the use of a video game. Building rewards and gratification into a product can increase a user’s motivation to continue usage. Turbotax designs for this principle by adding positive reinforcement into the interface after tasks are complete to motivate the user to continue on in the process.
Anxiety Anxiety is an emotion that has been shown to have both positive and negative influences on the functions of working memory. Eysenck defined anxiety as “an aversive emotional and motivational state occurring in threatening circumstances.” (Eysenck, 1992). This definition references the motivational element that is derived from anxiety. Anxiety arises when a person perceives worry, or “thoughts of potential threats that compete for resources in working memory” (Wetherell, Rynolds, Gatz, & Pedersen, 2002). These thoughts of worry consume space in working memory thus limiting the capacity, and decreasing the efficiency of working memory processes. (Eysenck & Calvo, Anxiety and performance: The processing efficiency theory., 1992) .This outcome accounts for the negative effects anxiety imposes on working memory. Conversely, anxiety can also have a positive effect on working memory by escalating the level of arousal, which forces the individual to be more vigilant and focused, thus increasing effort and overall performance on the task (Baddeley & Logie, 1999). Anxiety should be considered in design decisions by understanding the nature of the emotion and its effects on behavior. Designs should reduce anxiety and frustration wherever possible by using familiar technology and understanding the mental models and preferences of a user. Determining the ideal level of activation will also help appropriately motivate users to complete tasks. Turbo tax does a good job of understanding the anxiety commonly faced with filing taxes and the elements that could potentially hinder the user’s experience and performance.
Addressing emotions up front allows the user to understand the interface recognized these emotions and is there to help.
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