Our everyday activities involve managing sequences of thinking and anticipating, the “stream of consciousness”, and organizing this stream towards achieving a goal through reflective thinking (Carruthers, 2015). This evolutionary development in human cognition enables us with abilities that include the integration of perceptual information and stored knowledge, response inhibition, interference resistance, language enhancement, and thus, provides increased reasoning, planning, and general intelligence (Coolidge & Wynn, 2005). Working memory (WM) is the key system within which these processes occur and thus understanding its nature and limitations is crucial to aid human performance. Varying among individuals, performance is influenced by emotions as explained in the context of arousal theory, the effects of stress on an individual’s level of activity, and the processing efficiency theory (Daneman & Carpenter, 1983; Eysenck & Calvo, 1992; Selye, 1976). Thus, considering these factors will help a product designer cater to human limitations and craft an experience that can derive maximum efficiency.
Models and Components of Working Memory
Drawing inspiration from the distinction between temporary primary memory and durable secondary memory (James, 1890), the modal model includes sensory memory systems connected in parallel to short-term memory (STM) that holds and manipulates information which is then encoded to the long-term memory (LTM) (Atkinson & Shiffrin, 1968). However, this model assumed the degree of long-term learning depended on the length of time the item is held in STM rather than depth and richness of encoding (Craik & Lockhart, 1972), and could not explain why items processed in terms of appearance were poorly retained compared to those that were verbalized (Shallice & Warrington, 1970).
To explain this, the multicomponent model of WM proposed to replace the unitary STM by three components that include the central executive, an attentional control system, and two subsystems limited in capacity, the phonological loop capable of holding speech-based acoustic information comprising a phonological store and an articulatory rehearsal mechanism; and the visuospatial sketchpad capable of holding visual and spatial information (A. D. Baddeley & Hitch, 1974). But this model, could not explain the human capacity to process information in chunks. In contrast, the embedded-process model of working memory suggested a view oriented on the underlying cognitive processes rather than modularity and components of WM. It included activated memory, a part of LTM which consists of voluntarily or involuntarily activated elements needed to perform a cognitive task; and the focus of attention suggesting that the WM held a subset of the activated elements in focus (Cowan, 1998). But this model could not explain the reason behind varied processing of information from different modalities. To accommodate the process of semantically associating elements (A. D. Baddeley, Hitch, & Allen, 2009), and the research on individual differences in WM performance (Daneman & Carpenter, 1983), a fourth component, the episodic buffer was introduced to the multi-component model as an interface that binds perceptual information, information from sub-systems, and information from LTM to be integrated into temporary episodes that can accessed through conscious awareness (A. Baddeley, 2000, 2007). The distinctions drawn between the WM components can be explained primarily through its nature of being highly volatile, limited in capacity, and constrained by time.
Highly Volatile
Interference accounts for one of the most crucial implications of volatility in WM, forgetting (Anderson, 2003). The two WM subsystems are susceptible to concurrent similar code interference indicating that sequential verbal characteristics are more disrupted by concurrent verbal tasks than spatial tasks and vice versa for spatial characteristics (Vergauwe, Barrouillet, & Camos, 2010). Similarly, the central executive is disrupted by concurrent tasks involving processes that are controlled rather than automated (A. Baddeley, 1996). Interference can also occur from information learned from another time due to proactive interference, where activity engaged prior to the current task disrupts the latter (Jonides & Nee, 2006) and pronounced for people with low WM capacity (Kane & Engle, 2000); and retroactive interference, where a new learning can interfere with information from the past (Ellis, Shepherd, & Davies, 1979). In contrast, both concurrent and retroactive interference can be reduced if information from tasks are coded to be purely processed by different WM components (Hälbig, Mecklinger, Schriefers, & Friederici, 1998) as it involves efficient time sharing of resources (A. Baddeley, Chincotta, & Adlam, 2001). However, the efficiency of time-sharing may be reduced due to the similarity in the content held at the same time in the WM (Hirst & Kalmar, 1987). To counter the effects of volatility and increase performance, the WM components may be involved in covert rehearsal processes like selective spatial attention for spatial working memory (Awh, Jonides, & Reuter-Lorenz, 1998), and covert speech for the articulatory loop aided by the executive functioning of the central executive involved in interference resistance and inhibitory control (Anderson, 2003; Banich, 2009). But, growing inefficiencies in inhibitory control due to aging may decline WM performance and similar degraded performance associated with the access and restraint functions of inhibition can be observed in individuals with reading disabilities at all ages (Chiappe, Siegel, & Hasher, 2000). Furthermore, stress, an emotional state of heightened arousal from environmental as well as psychological factors such as anxiety, can increase performance if the level is below an optimal threshold, however, higher levels may decrease performance as they start to produce attentional difficulties and higher cognitive interferences (Coy, O’Brien, Tabaczynski, Northern, & Carels, 2011).
Limited in Capacity
Initially identified as 7±2, then downgraded to three or four, the maximum number of items recalled with complete attention employed to rehearsal, immediately after their presentation is termed Memory Span (Conway et al., 2005; Cowan, 2010; Miller, 1956). Although the exact number depends on the task and pattern, information about the shape, color, and texture is retained in the visual working memory, by focusing on one aspect each among rapid fixations, in a need-to-know fashion implying the phenomenon of change blindness (Irwin, 1992; Rensink, 2005). As a limited capacity system, when the demands of the tasks exceed the resource supply, a case of workload overload, individuals may allow performance degradation, switch to satisfactory heuristics or shed tasks (Hart & Wickens, 1990). On the contrary, individuals in a motivational state of mind show a greater memory span due to increased receptivity for incoming information (Heckhausen & Gollwitzer, 1987). Furthermore, the proportionality between decay and number of items in the working memory as shown in the Brown-Peterson paradigm (Melton, 1963), denotes a longer delay between the successful rehearsals of each item in the phonological store. Moreover, the differences in the speed of rehearsal among people, specifically experts, suggest that the WM capacity is influenced by information from LTM to group items in a meaningful way into a single perceptual unit or chunk (A. D. Baddeley, 1997; Chase & Simon, 1973). Equipped with the ability to rapidly encode frequently encountered chunks into LTM, experts develop larger templates compared to novices who rely on smaller chunks in the limited capacity WM susceptible to interference (Gobet & Clarkson, 2004; Ye & Salvendy, 1994). In addition, reduced storage and processing is observed in individuals with high levels of anxiety as the limited capacity may be unduly occupied with thoughts of what might go wrong leaving less capacity for the current task (Eysenck & Calvo, 1992). However, superior anticipation skills in the domain of expertise help experts perform better than novices in such situations (Darke, 1988; Williams & Elliott, 1999).
Constrained by Time
Numerous variations of the Brown-Peterson paradigm demonstrate the transient characteristic of WM suggesting that little information is retained in the absence of continuous rehearsal (Loftus, Dark, & Williams, 1979; Moray, 1986). This notion forms an important part of recent WM models that suggest tasks involving short interval information presentation that demand verbal working memory are more readily served by speech leveraging the fact that echoic memory, a sensory auditory store, has a slower decay than iconic memory and also because speech has obligatory access to the phonological store and higher compatibility with rehearsal (Wickens, Sandry, & Vidulich, 1983). In contrast, it is found that more information can be retained with longer viewing through the visual working memory implying that decay is not just related to time, but also to interference by other factors and complexity of the material to be remembered (Lewandowsky, Oberauer, & Brown, 2009). Applicable to both spatial and verbal WM, transience is a serious problem when items to be remembered cannot be rehearsed due to interference and also intervening tasks. However, experts’ ability to resume a skilled activity without a degrade in performance after an interruption includes access to long-term WM which is stable with a longer time constant, and accessed through retrieval cues supported by templates in WM (Ericsson & Kintsch, 1995).
Product Review
Considered as the backbone of India, Indian Railways caters to millions of passengers every day by operating hundreds of trains that connect every town, city, and village in the country. The affordability, convenience, and comfort of traveling by train present a train ticket with a higher value for money compared to its counterparts like flight or bus and thus, it is always in high demand from individuals of all ages. A typical 600 seat train is completely booked at least weeks in advance to the date of the journey through ticket purchase facilities accessed via counters at railway stations or the internet portal – www.irctc.co.in, which is the target of this product review. However, to accommodate emergency situations, a new series of a limited number of tickets or quota was introduced called “Tatkal”, typically around 50 tickets, which can be accessed via the two same channels only at a specific time on the previous day of the journey. Thus, thousands of people compete for Tatkal tickets every day consuming the Tatkal quota in a few minutes after it is opened to the public. Furthermore, to make sure that this facility is not exploited by people, the internet portal automatically logs out a user after 5min of inactivity.
Context
John Smith, an elderly gentleman based in Bangalore, wants to visit his daughter, who is based in Mangalore, after he receives the good news that she has just given birth to his granddaughter. He wants to utilize the tatkal service for this unplanned event and thus, opens the internet portal (Fig.1) exactly at 11:23 am, keeping in mind that the tatkal tickets would be made available at 11:25 am and abiding by the 5min inactivity clause. He receives the train number (165-15), and the train name (Yeshvantpur Karwar Express) from his daughter at 11:20 am. With increased receptivity due to the motivation to meet his granddaughter, these data points are currently in his phonological loop going through covert speech rehearsal and waiting to be encoded into LTM.
Anxious about his chances of getting a ticket, he types Bangalore in the “From” text field of the home page.
Negative. The “From” text field does not take consider the full name of the location, in this case, Bangalore. Instead, it considers mnemonics that is remembered only by expert users of the system, in this case, SBC. So, John has to search and remember the mnemonic for both Bangalore (SBC) and Mangalore (MAQ) and then enter them in their respective fields which might lead to concurrent use of the same WM subsystem and thus, interference. The system should be designed to accept most common inputs, rather than expecting the users to remember mnemonic codes.
As the clock ticks to 11:24 am, John is even more anxious about his chances as he is directed to the train schedules between the two cities (Fig 3, next page). This page is filled with a lot of data points that John has to process to identify the train name and number.
Negative. The advertisement in the middle of the page distracts users in a time when they are more susceptible to interference considering the fact that John’s age has led to inefficiencies in inhibitory control. The number of data points in the screen, like the refine results tab in the left, makes it harder for a user to quickly identify a specific train number or name. Information related to the train is not organized for easier processing (Green outline in Fig 3): the name of the train is written in abbreviations (YPR KAWR EXPRES), and the train number is not chunked making it harder to process; less important information like other days of departure, and redundant iconography used for departure and arrival time are present in the same row as train number, acquire attention and WM space but do not add any value to the task. Consider organizing this page to aid the efficient processing of information.
Negative. The most important step of this process is to select the Quota as Tatkal (Dashed orange rectangle in Fig 3) and the page has not been designed to provide enough attention to this dropdown. The failure of a user in identifying this step will lead to more anxiousness, degradation in performance and in turn, satisficing or shedding the current task. Fortunately, the first option on the screen is what John was looking for. Overloaded with information, he clicks the row to go to the next step but then realizes that clicking on the “Check Availability” button will only take him to the next step.
Negative. The “Book Now” button won’t be active until the exact time 11:25 am. Thus, John’s spatial working memory is going through a covert rehearsal process of selectively focusing on one specific part of the website (orange rectangle in Fig 4). However, as his anxiety levels increase, his limited capacity working memory is interfered with the advertisement below the “Book Now” button and misses the time spot by a few seconds leading to more anxiety.
As soon as he clicks “Book Now”, a pop-up appears (Fig 5) asking him to login and also enter a Captcha code further increasing his anxiety as it will decrease his chance of securing a ticket.
Negative. Consider including the login screen either while starting the process or after securing a seat. Furthermore, the Captcha code (bounded by orange in Fig 5) appears minuscular compared to the advertisement above it which leads to higher processing power in the anxiety consumed memory capacity
After logging in, John is directed to the passenger details screen (Fig 6), where he has to enter his details.
Negative. In such situations where users are under time stress to perform an action, human performance can be supported by pre-filling the text fields with the passenger’s details rather than asking the user to retrieve stored memory and enter it into the interface. Furthermore, there is another Captcha to move to the next step (bounded by orange in Fig 6), which has very similar problems as the previous one. In addition, as this Captcha enters John’s WM, it might be interfered proactively by Captcha he used in the last step and also due to the similarity in the number of digits taking into account that the code is not chunked for easier processing. To supplement it, because of the paucity in time John’s working memory may not have enough time to rehearse the code leading to inefficiencies.
Positive. John is asked to review the travel details on the next page before booking his seat. The ability to look at all the important details regarding the journey on a single page gives the fatigued working memory a chance to selectively scan, process and correct mistakes.
Conclusion
Although the human working memory is limited, volatile and transient in nature, a product designer can overcome these limitations by designing the right support system, analyzing task demands, triggering the right emotion, and decreasing interference.
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