My
question here is to deal with the interface design on Global Positioning System (GPS). As
we may be aware, a GPS device usually provides three features: 1. Audio system
broadcasting instantly when direction changes; 2. Textual information showing
instructions; 3. an up-to-present map occupying a large portion of LCD display.
Based on Baddeley’s (1986) working memory model, as Wicken et al. (1983, 1984)
argued before, the display format should fit the subsystems used to perform the
task in the working memory. This implication somehow triggers my interest in
two coarsely defined inquiries below:
- Which feature is most helpful for people to drive in an unfamiliar area;
- If that feature is found, will the effect be improved or diminished by adding additional feature(s)?
What
people hear from audio will be encoded in the phonological store, so will the
textual data presented to drivers; at the same time, the spatial information
from the map will go to visuospatial sketch pad. The driving routes may upgrade
at varied intervals depending on characteristics of the area, so people have to
receive new information from time to time while following the old instructions
correctly. Although the verbal information will eventually go to visuo-spatial
sketch pad, the central executive need to transfer information, synthesize
information, and analyze information. Those activities add the pressure of
cognitive load that constantly looks for available attention resources. In that
sense, from the perspective of decrementing cognitive load while satisfying
working memory’s need, we may just need the map, or a combination of two
features; perhaps the presence of certain feature will deteriorate the benefits
from other feature(s).
Another aspect
of this problem is pertaining to human information processing, specifically the
attention. In a complex environment like driving, we are watching the traffic,
listening to radio/GPS instructions, controlling the speed, probably talking on
the phone. Thus, we have used three attention resources already, which are
namely sight, touch and hearing. Furthermore, when we discuss the concept of
selective attention, they are most likely related to visual perception, and it
is basically the product of four factors: salience, effort, expectancy and
value (Wicken et al., 2003).
To explain each of them in order, first of all, as what the “salience” means, some unique feature may attract you right away from other less salient objects, for instance, a horse running in the high way with cars; typically, the auditory signal is more attention-grabbing than visual affairs, that is why we often take actions upon hearing the alarm. If the sound is replaced by the flashing LED light, we would imagine how long it is going to take us to notice a potential miserable event. The second variable is expectancy, which is defined as the knowledge with respect to probable time and location of information availability. Imagining that you are driving in a mountain with lots of sharp turns, you should keep an eye on the curvy road more continuously when you are traveling fast; on the other hand, if you are just cruising around Chicago on lake-shore drive, most of the road are straight, so you can relax a little bit and attend to your music more than the road. The third factor is the value of information.
Let us illicit the concept by referencing the same instance of driving, it makes sense for people to look forward most of time, because you want to be quick to take actions whenever see something occurring. With the second and third factor introduced, there is actually an interaction between them, if we multiply the expectancy with value; we can obtain a better function of selective attention, which can be de-abstracted in this way: an experienced air traffic control of certain airport know where to scan most and when. Last but not least, effort. As we know, most of people only can pay attention to one thing at one time, if you focus on the mirror trying to change lane, you probably would not share this effort with looking toward, because it simply cannot be achieved by the majority of human beings. Hereby, the effort seems to appear as a negative value, as attention allocations to multiple places may decrement operation performance as a result.
To explain each of them in order, first of all, as what the “salience” means, some unique feature may attract you right away from other less salient objects, for instance, a horse running in the high way with cars; typically, the auditory signal is more attention-grabbing than visual affairs, that is why we often take actions upon hearing the alarm. If the sound is replaced by the flashing LED light, we would imagine how long it is going to take us to notice a potential miserable event. The second variable is expectancy, which is defined as the knowledge with respect to probable time and location of information availability. Imagining that you are driving in a mountain with lots of sharp turns, you should keep an eye on the curvy road more continuously when you are traveling fast; on the other hand, if you are just cruising around Chicago on lake-shore drive, most of the road are straight, so you can relax a little bit and attend to your music more than the road. The third factor is the value of information.
Let us illicit the concept by referencing the same instance of driving, it makes sense for people to look forward most of time, because you want to be quick to take actions whenever see something occurring. With the second and third factor introduced, there is actually an interaction between them, if we multiply the expectancy with value; we can obtain a better function of selective attention, which can be de-abstracted in this way: an experienced air traffic control of certain airport know where to scan most and when. Last but not least, effort. As we know, most of people only can pay attention to one thing at one time, if you focus on the mirror trying to change lane, you probably would not share this effort with looking toward, because it simply cannot be achieved by the majority of human beings. Hereby, the effort seems to appear as a negative value, as attention allocations to multiple places may decrement operation performance as a result.
To
summarize the massage for selective attention, researchers often refer to the
following model:
P(A) = sS
– efEF + exEX * vV (Wickens et al. 2003)
(“sS” refers to “salient feature”; “efEF” means
“effort”; exEX corresponds to “Expectancy”; and “vV” points to “value”)
Applying
this model to our question of interest, GPS can produce audio instructions that
are more salient than visual in theory; in the meanwhile, the effort to
receiving auditory information usually cost less compared to reading
information from the screen, although the GPS is attached to the windshield. However,
this effort can reach a margin-value when it comes to a complex area such as
6-way intersection. In this scenario, visual feedback is better, because in
other case, our center executive has to consume more attention resources, as
the textual information needs to be rehearsed by articulatory loop, and then
converted to visual data for further processing. With respect to value and
expectancy, they are inconsistent depending on the routes, thus hard to
predict. Collectively speaking, the problem domain is very interesting to look
into, and we may even resort to AI to help us determine which method is more
effective and safe.
To
address those two questions, an experiment may be acquired. In addition, a set of
independent/ dependent variables should be defined along with a reasonable
measurement. Without going to much detail, I think the independent variable
would be of categorical type (e.g. audio, text, and map), the dependent
variable could be “helpfulness” gauged by “time to drive to destination”,
“level of satisfactions”, and “fuel consumed”, while each element carries
different weight. For the concern of safety, the study can also be conducted
virtually in a lab, given the fact that there are many driving training games
available; additionally, we are capable of controlling possible confounding
factors relatively easier in the lab condition. In terms of the analysis
method, ANOVA would be optimal; because three types of treatments are seen
here, and we aim to find out whether there are real differences among them
(statistics such as F–value need to
be reported).
Reference:
Baddeley, A. D. (1986). Working memory.
New York: Oxford University Press. Baddeley, A. D. (1992). Working memory. Science, 225, 556-559.
Wickens, C. D., and Carswell, C. M.
(2006). Information Processing. In Salvendy, G. (Ed.), Handbook of Human
Factors and Ergonomics, 3rd Edition, 111-149, Hoboken, NJ: Wiley.
Wickens, C. (1980). The structure of
attentional resource. In R. S. Nickerson (ed.), Attention and Performance VIII,
239-257, Hillsdale, NJ: Lawrence Erlbaum.
Wickens, C. D., Vidulich, M., &
ILLINOIS UNIV AT URBANA ELECTRO-PHYSICS LAB. (1982). S-C-R Compatibility and
Dual Task Performance in Two Complex Information Processing Tasks: Threat
Evaluation and Fault Diagnosis. Ft. Belvoir: Defense Technical Information
Center.
(© 2012 Miaoqi Zhu)