Faster Progress Bars: Manipulating Perceived
Duration with Visual Augmentations
Chris Harrison
Zhiquan Yeo Scott E. Hudson
Human-Computer Interaction Institute, Carnegie Mellon University
5000 Forbes Avenue, Pittsburgh, PA 15213{chris.harrison, zyeo, scott.hudson}@cs.cmu.edu
ABSTRACT

Human perception of time is fluid, and can be manipulated
in purposeful and productive ways. In this note, we propose
and evaluate variations on two visual designs for progressbars that alter users’ perception of time passing, and “appear” faster when in fact they are not. As a baseline, we use
standard, solid-color progress bars, prevalent in many userinterfaces. In a series of direct comparison tests, we areable to rank how these augmentations compare to one another. We then show that these designs yield statisticallysignificantly shorter perceived durations than progress bars
seen in many modern interfaces, including Mac OSX. Progress bars with animated ribbing that move backwards in a
decelerating manner proved to have the strongest effect. Ina final experiment, we measured the effect of this particular
progress bar design and showed that it reduces the perceived duration among our participants by 11%.
ACM Classification: H5.2 [Information interfaces andpresentation]: User Interfaces. - Graphical user interfaces.
General terms: Design, Human Factors
Keywords: Progress bars, percent-done indicators, perception, perceived performance, induced motion.
INTRODUCTION

Progress bars [8], typically used to visualize the progression of an extended operation, are prevalent in current userinterfaces. In desktop systems, advanced users often multitask during these periods. However, it is not uncommon foradvanced users to watch an install finish or file transfer
complete – especially if they are waiting on that operation.
Anecdotally, novice users tend to anxiously monitor theirprogress bars, in hopes that some error does not occur. In
non-desktop applications (e.g., ATMs, ticketing kiosks, andsome mobile device platforms), novice and expert users
alike have no choice but to watch progress bars frustratingly inch their way across the screen. No matter how objectively fast we make these operations, it is typically the
subjective speed that mars the user experience [11]. Indeed,a core tenet of HCI is to improve user satisfaction.
Previous research has shown that the perceived duration ofprogress bars can be manipulated by changing how they
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move (e.g., pauses, accelerations) [4]. We extend this exploration to the manipulation of visual attributes. Following
a series of head–to-head comparisons of perceived duration
for different visual styles, we conclude with an experimentthat quantitatively assesses the perceptual improvement
over the ubiquitous, solid-color progress bar.
This work adds to the nascent field of time design [5,9] – adiscipline that looks at how temporal aspects of interactive
systems can be structured and manipulated to improve theuser experience. It is argued that subjective time is not only
the most readily manipulated, but also the most important[11]. After all, our perception is our reality. Finally, withgood design, such benefits can often be realized immediately and essentially for free (i.e., we do not have to makefaster computers to make computers feel faster).
STUDY 1: PULSATING PROGRESS BARSFrequency variations in rhythmic stimuli have been shown
to affect peoples’ perception of time [7]. We hypothesizedthat this effect could be used to reduce the perceived duration of progress bars. To test this, we designed several variations of a progress bar that used a sinusoidal visualpulsation, causing the progress bars’ fill color to vary between light blue and blue.
Study Design

To investigate how pulsation can be used to manipulate
perceived duration, we recruited 20 participants (7 female,mean age 23) to evaluate five distinct behaviors we had
Behavior Name
Constant
Slow Increasing
Fast Increasing
Slow Decreasing
Fast Decreasing

Start Frequency(0% Progress)
1.1 Hz1.1 Hz1.1 Hz1.1 Hz1.1 HzEnd Frequency(100% Progress)
1.1 Hz1.17 Hz1.25 Hz0.95 Hz
0.8 HzTable 1. The five pulsating progress bar behaviors.

Figure 1. The study interface.

created (Table 1). To identify perceptual differences, weemployed a simple interface that presented two progressbars to the participant (Figure 1), each of which took fiveseconds to complete. Progress bars were run sequentially –when the first one finished, the second one began. Sequential, rather than parallel presentation was necessary to hide
the fact that the progress bars were actually the same duration. Although five seconds is a somewhat short duration
for a progress bar, it was a necessary trade off to run thenumber of trials we desired and still maintain user attention
for the complete experiment. However, as you will see in
discussion of the results from our final experiment, we believe that these types of effects can scale to at least somewhat longer durations.
After watching the two progress bars run to completion,
participants selected whether they believed the first progress bar was faster, the second progress bar was faster, orthat the progress bars were equal in duration. The next trial
began once an answer was provided. Participants could
replay the progress bars if desired.
All distinct ordered pairings of the five pulsation behaviors
were shown to participants, for total of 25 trials. This included testing behaviors against themselves, and both orderings of every pair, the results of which are combined tocontrol for order effects. Presentation order was also
randomized to control for time order errors (see [3], p52).
Results and Discussion

We employed a simple preference metric [4] to compare
the performance of different behaviors, which is calculated
as an average of the following individual scores: +1 if thefirst behavior is preferred (i.e. perceived to be faster), -1 if
the second is preferred, and 0 if the participant believed thetwo to be equal in duration. For example, in 40 comparisons of Fast Increasing vs. Slow Decreasing, 16 participants felt the former was faster, 6 participants felt the latter
was faster, and 18 believed the two progress bars wereequal in duration. Thus, the mean preferences score is (16 –6) / 40 = 0.25. The positive value indicates a preference
towards Fast Increasing. To derive our statistical measures,
we employed a two-sided sign test of the null hypothesisthat each function was equally likely to be preferred.
There were several statistically significant differences in
the preferences between the various pulsation behaviors.
Figure 2 provides a partial order of these relationships, andclearly illustrates the preference towards behaviors withincreasing pulsation frequencies. This result is confirmed
when results are grouped by behavior type – behaviors with

Figure 2. Statistically significant preferences between
the five pulsation behaviors. Thin lines indicate significance at p<0.05; thick at p<0.001. Mean preference
scores are labeled on the edges.

Figure 3. Progress bar used in Mac OSX.

Figure 4. Ribbed progress bar used in the study.

increasing frequency are significantly preferred over thosewith constant or decreasing frequencies (p<0.05 and
p<0.001 respectively). The most preferred behavior overall
was Fast Increasing, with a mean preference score of 0.21.
STUDY 2: RIBBED PROGRESS BARS

Ribbed progress bars have been a stable visual element of
Mac OS X since its earliest releases (Figure 3). These progress bars, like others, progress from left tor right, but also
feature an animated ribbing which moves from right to left.
The visual qualities of ribbing are well suited to take advantage of induced motion effects, which state that motion
perception is not absolute, but rather relative to the surrounding visual context [6,10]. Thus, ribbing moving in the
opposite direction to the progress creates an illusion of increased velocity, which in turn, alters our perception ofprogress bar duration.
Study Design

To investigate how animated ribbing affects perception ofprogress bar duration, we devised seven ribbed behaviors,
described in Table 2. We used the same participants as thepulsating progress bar study. Figure 4 illustrates the graphical appearance of our ribbed progress bars (although notanimated). Using the same study interface (Figure 1), we
presented all 49 distinct ordered pairs of the seven ribbed
behaviors. As before, this included testing behaviors
against themselves, and both orderings of any given pair,
the results of which are combined to control for order effects. Presentation order was also randomized.
Results and Discussion

Participants had strong preferences among the seven ribbed
behaviors (Figure 5). When grouped by direction of ribbing, backwards-moving behaviors were significantly preferred over both still and forward ones (p<0.001 for both).
When grouped by change in velocity, accelerating behaviors (both forward and backwards) were significantly preferred over still ribbing (i.e., no velocity, p<0.05), while
decelerating behaviors are significantly preferred over bothstill and constant velocity ribbing (like that seen in Mac
Behavior Name
Still (no velocity)
Backwards Accel.
Backwards Decel.
Backwards Const.
Forwards Accel.
Forwards Decel.
Forwards Const.

Initial Ribbing
Velocity
0 (mm per second)-7.8 mm/sec-31.3 mm/sec-15.6 mm/sec
7.8 mm/sec
31.3 mm/sec
15.6 mm/sec

End Ribbing
Velocity
0 (mm per second)-31.3 mm/sec-7.8 mm/sec-15.6 mm/sec
31.3 mm/sec
7.8 mm/sec
15.6 mm/sec

Table 2. The seven ribbed progress bar behaviors.
Negative values indicate ribbing moving to the left
(opposite to the direction of progress). The progress
bar moved right at 128 pixels per second.

also randomized. The study was completed for both 5- and15-second durations (36 comparisons in total) using thesame interface as the previous two studies.
Results and Discussion

Figure 5. Statistically significant preferences between
the seven ribbed behaviors. Line styles: dashed(p<0.1), thin (p<0.05), thick (p<0.01). Mean preference scores are labeled on the edges.

OSX) (p<0.05 for both).
Progress bars with backwards-moving ribbing that were
either accelerating or decelerating performed the strongest.
The theory of induced motion would suggest that Backwards Accelerating ribbing would be ideal, providing thehighest relative velocity of any behavior (264 pixels per
second near the conclusion - a particular salient area due topeak and end effects [1]). Indeed, although not statisticallysignificant, Backwards Accelerating is slightly preferredover Backwards Decelerating (a weak preference score of0.1). However, if the preference scores against all otherbehaviors are averaged, Backwards Decelerating has thegreatest overall preference (0.34 vs. 0.29). Additionally,amongst the statistically significant relationships, Backwards Decelerating had both more significant and higher
magnitude preferences (Figure 5).
STUDY 3: PULSATING AND RIBBED COMPARED

The previous two studies identified which pulsating andribbed behaviors were the strongest within their respective
groups. However, the results offered no insight into how
these visual augmentations compared against each other orstandard, solid-color progress bars. Thus, a new study wasdevised that pitted three types of progress bar against eachother: a standard, solid-color progress bar, the bestperforming pulsating progress bar (Fast Increasing), and thebest-performing ribbed progress bar (Backwards Decelerating).
Study Design

We recruited 10 participants (5 female, mean age 19) toevaluate the relative perceived duration of the three progress bars at two different durations, 5 and 15 seconds. The
latter time was included to explore if the perceptual effects
scaled to somewhat longer intervals (both durations arewell below Vierordt’s threshold [12], minimizing perceptual distortion between the two conditions. Nonetheless, tocontrol for any e.g., attenuation effects [2], we do not compare results across durations). Each unique ordered pair ofprogress bars was presented to participants twice, for a totalof 18 trials. Data from repeated trials was combined, as
were results from different presentation orderings of thesame pair (to control for order effects). The trial order was

There was only one preference approaching significanceamongst the three progress bars at the 5-second duration:
the progress bar with increasing pulsation was more likely
to be perceived as having a shorter duration (i.e., faster)than the standard, solid-color progress bar (p<0.1). However, the results from the 15-second duration comparisons
showed that both the ribbed and pulsating progress bars
were significantly preferred over the standard, solid-color
progress bar (p<0.05). In trials that compared ribbed withpulsating progress bars, ribbed was slightly preferred.
When combing results from the 5- and 15-second duration
tests, 30 trials indicated a preference for the pulsating behavior, 33 indicated a preference the animated ribbing, and17 trials noted no preference (equal duration).
STUDY 4: PERCEIVED PERFORMANCE MAGNITUDE

Our previous studies indicated which visual behaviors led
to a perception of decreased progress bar duration. However, they did not directly measure how much faster they
were. In response, we initiated a final round of experimentation that was explicitly designed to gauge the magnitudeof the perceptual effects we had seen.
Study Design

For our final study, we selected a progress bar that featured
Backwards Decelerating ribbing, as this was slightly preferred over the pulsating behavior in study three. This wascompared against a standard, solid color progress bar. The
test interface, instead of simply recording participant’s
preferences, used the responses to warp the duration of theribbed progress bar (the solid color progress bar had a fixed
duration to act as a control). Specifically, if a user felt theribbed progress bar was faster, its duration was extended(to slow it down). Conversely, if the user felt the ribbing
was slower, the duration was reduced (to speed it up).
Equal responses left the duration unchanged. The goal was
to allow participants to converge to a duration where they
believed the two progress bars “felt” equal. (For an extended discussion on method of adjustment experiments,
please refer to [3], “Difference Thresholds”).
As before, two progress bars durations were evaluated: 5
and 15 seconds. The latter was included as a preliminary
test to see if the effects extended to longer periods (alreadypartially demonstrated in the study 3). We piloted withlonger durations, but it was clear that participants’ attention
suffered tremendously. We presented both orderings ofeach duration (solid-color first and ribbed first), yielding
four distinct experimental conditions, for which duration
warping was handled independently. Results from the twoorderings were combined at the end of the study to control
for order effects.
We recruited 16 participants (6 female, mean age 22). Participants had eight rounds to find a perceptual equilibrium
for each of the four conditions. This was repeated twice(with data averaged together) for a total of 64 trials (fourFigure 6. Results from the perceived performance magnitude experiment.

conditions of eight rounds each, done twice), the order ofwhich was randomized to control for time order errors.
The time that was added or subtracted to the ribbed progress bar duration decreased linearly each round, allowing
for increasingly fine tuning. This value started at 25% of
the total original duration, and then dropped by 5% eachsubsequent round. For the final three rounds, a fixed valueof 2.5% of the original duration was used. In the firstround, the “equal speeds” answer button was disabled,
forcing participants to select either the standard, solid color
progress bar or the ribbed progress bar as being faster. This
helped to kick off the convergence (participants could invert the relationship if, e.g., they chose incorrectly, in as
little as two rounds).

forming behavior, a backwards moving and decelerating
ribbed progress bar, and compared its perceived performance to that of standard, solid color progress bar. This wasachieved using a special interface that manipulated the actual duration of the ribbed progress bar, allowing users tofind a perceptual equilibrium. Results show that the selected visual augmentation caused users to believe it had aduration equal to that of a progress bar 11% longer in actual time. In other words, visually augmented progress bars
could be used to make processes appear 11% faster, whenin reality, their duration remains unchanged.

Results and Discussion

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Figure 6 displays the results of the duration matching trials.
In both cases, the Backwards Decelerating ribbing significantly increased perceived performance (p<0.001). On average, a 5 second solid color progress bar felt perceptuallyequivalent to a 5.61 second ribbed progress bar (SE=0.14),
which is 12.2% longer in actual duration. A similar effectwas seen in the case of the 15-second duration tests, where
the ribbed progress bar was converged to an average of
16.75 seconds (SE=0.45), an 11.7% increase in actual time.
The similarity in the magnitude of the two results suggests
these effects might scale linearly to longer durations, but
additional tests will be needed to confirm this.
Another interesting result is that unlike the 5-second duration results, which level off quickly (by roughly roundfour), the 15-second results show a clearly upward trajectory, even at round eight. It is possible that the longer duration necessitates additional rounds to find a perceptual
equilibrium. If this trend does exist, it would suggest an
even greater perceptual performance effect is at play, andpossibly that the effect magnifies as duration increases.
CONCLUSION

In this paper, we have explored two classes of visual augmentations that could be applied to progress bars: a pulsating effect and an animated ribbing. We described the results from four studies that sought to identify which visual
behaviors could improve the perceived performance of aprogress bar. In our final experiment, we took our best per-ACKNOWLEDGEMENTS

This work was supported in part by grants IIS-0713509 and
IIS-0840766 from the National Science Foundation.