Time Perception
[Publishers are always concerned about the number of pages in a book, so to pare down an earlier edition of the text, this section was removed. It's now a bit dated, but I'll make an effort to update it when the smoke clears a bit.]
Perhaps
you have an uneasy feeling as you begin to read about time perception. Color
perception, shape perception, and distance perception all refer to tangible
attributes. Even loudness, pitch, and motion perception seem reasonably
concrete. But time perception? The topic refers to something
invisible and fleeting. We have seen how photoreceptors register information
about light and hair cells register information about sound, yet no receptor
registers information about the passage of time. And consider the stimulus
for time perception. A square or a red patch exists, yet as
Fraisse (1984) points out, "Duration has no existence in and of itself" (p. 2).
Although
invisible and fleeting, time is an essential variable in perception. The
timing of the stimuli must be precisely correct for backward masking to occur,
for example. The timing of the two stimuli in stroboscopic movement studies
must be equally precise; the phenomenon is lost if the interval between the
two stimuli is too long or too short. Careful regulation of the interval
length can produce the impression of an object moving through space or — by
extending the interval by less than one tenth of a second — the impression
of movement unaccompanied by an object (phi movement). A sound that arrives
at one ear a small fraction of a second after it arrives at the other ear provides
us with information about the location of the sound source. Virtually
every experiment in perception specifies how long a stimulus was exposed to
observers, how long observers were allowed to dark adapt, the number of cycles
that a sound wave completes in 1 second, or some other characteristic related
to time.
However,
until now, time has been on the periphery of our discussion. Now we'll
make it our central issue. Block (1990) has identified four factors that
provide a context within which psychological time is perceived: characteristics
of the time experiencer, time-related behaviors and judgments, contents of
a time period, and activities during a time period. We will adopt Block's
framework, and discuss each of the four factors. Although we will consider
each factor separately, Block stresses the interrelationships among the four
factors; changes in one factor are likely to induce changes among the other
factors.
Characteristics of the Time Experiencer
In The
Hitchhiker's Guide to the Galaxy, Douglas Adams (1979) satirizes the
foibles of modern people, including our obsession with digital wristwatches. Keeping
track of the passage of time is certainly important to many people, but
the level of concern varies among cultural groups and even among people
of a single culture (Levine, 1988; 1990). The pace with which people
lead their lives certainly indicates the extent to which their actions
are in keeping with the Latin phrase "Tempus fugit" ("time
flies").
In developing
objective measures of the importance of time to people in various American
cities, Robert V. Levine (1990) and his colleagues made use of four measures:
the speed with which bank tellers made change, the talking speed of postal
clerks, the walking speed of pedestrians, and the proportion of pedestrians
wearing wristwatches. Levine found that the Northeastern United States
is more fast-paced than the Western United States. For instance, the
three fastest-paced cities surveyed were Boston, Buffalo, and New York. The
three slowest-paced cities surveyed were Shreveport, Sacramento, and Los Angeles. Furthermore,
there was a moderate correlation between the pace of life and the rate of death
from heart disease. Because of the correlational nature of the study,
one cannot conclude that a faster pace of life leads to an increase
in heart attacks. Nonetheless, the results are intriguingly consistent
with our beliefs about the relationship between stress and heart disease.
Without
a timepiece, or even conscious awareness, people perceive the passage of time. For
instance, many of us believe that we can go to sleep without an alarm and wake
up at a predetermined time. In fact, the evidence suggests that although
more people can perform such a feat than should happen by chance, a relatively
small proportion of us possess this particular ability (Campbell, 1990) . Nonetheless,
virtually everyone is aware of the passage of time, and can estimate its passage
with some accuracy. The means by which organisms perform this task, however,
remains something of a mystery.
Many organisms,
including humans, appear to organize their lives around the light/dark cycle
of a typical day. The behavioral patterns that emerge are referred to
as circadian rhythms because they are organized around a period
of approximately one day (in Latin circa means approximately and dies means
day). The adaptive advantages of using external cues from the environment
are apparent. If an organism could use sun-position cues, for example,
to keep track of the passage of time, then it could tell that a flower's nectar
was likely to have been replenished or that prey are likely to return to drink
from a river. As a result, if you feed an animal at a regular time, it
will begin to salivate in anticipation of food at the appropriate time, even
if no other feeding cues are present (Campbell, 1990) .
External
cues, such as the sunrise, serve to trigger circadian rhythms, which then continue
without additional external input (Block, 1990) . In the absence
of continuous time-of-day cues, many internal states exhibit circadian rhythmicity,
including hormonal levels and body temperature. Such circadian rhythms
are the product of an internal clock of some sort. Research suggests
that this biological clock might well be located in a brain structure near
the optic chiasm (Block, 1990). The nearness of the biological clock
to the visual pathway illustrates the importance of light as a trigger mechanism.
Imagine
what would happen if you were to live for a long while in a cave or a room
with only artificial light and no clocks. In the interest of research
on time perception and circadian rhythms, several people have lived under just
such conditions. The length of their "day" becomes elongated,
and is often roughly 25 hours long. Further, when asked to estimate the
length of an hour by pressing a button with the passage of each hour, the typical
subjective hour is longer than an actual hour. People's estimates are
also widely variable, suggesting that judgments of these durations are extremely
imprecise. In Scott S. Campbell's (1990) terms, estimation of these longer
durations is characterized by both sluggishness and sloppiness.
Time perception
might well be influenced by physiological state, knowledge, personality, and
other factors. For instance, there is some evidence that a person with
a high fever shortened her estimates of a 1-sec interval and that a person
who lived in a cold cave lengthened his time estimates. The evidence
for the contribution of metabolic rate to time perception is weak, but would
be consistent with a biological clock. The fact that knowledge and experience
also play a role (Theme 4), however, argues that there is a cognitive component
in time perception. Alberto Montare (1985; 1988) has found that providing
feedback to people about the accuracy of their time estimations increases the
accuracy of subsequent judgments. Montare did not find gender differences,
suggesting that time perception might be equivalent among men and women.
Overall,
then, the research suggests that people have a biological clock that regulates
various internal circadian rhythms. However, because of the sloppiness
and sluggishness of that regulation, and because of the effects of experience,
it is unlikely that our perception of time is due solely to this same clock.
Time-Related Behaviors and Judgments
We've
already mentioned some ways in which researchers have assessed people's perception
of time. Dan Zakay (1990) provides several examples of methodological
differences and the ways in which they might influence judgments of time. It
is important to discuss these various measures because, as Fraisse (1984)
emphasizes, "Results are neither comparable nor homogeneous across methodologies" (p. 10). We
will now discuss four classes of measures, or dependent variables, used by
researchers in studying time perception: estimation, production, reproduction,
and comparison (Zakay, 1990).
There are
several variants of the estimation procedure. First, participants in
the study could simply estimate time passage in some standard units of time
such as seconds or minutes. A duration could be presented, and immediately
after the time period, participants would estimate time passage. Time
estimation could also be assessed using the some of the psychophysical methods
discussed in Chapter 2. For instance, rather than estimating the number
of minutes or seconds that had passed, participants could assign a number value
or a line length to match their impression of the duration. Finally,
an estimation might be made with a rating scale. For example, the two
ends of the rating scale might be labeled "short time interval" and "long
time interval." Alternately, the ends might be labeled "time
passed quickly" and "time passed slowly" (e.g., Joubert, 1984).
A second
class of dependent variable involves time production. Participants could
be told to press a button and release it, for example, when they thought that
2 minutes had passed. This procedure can be used to explore time perception
in both humans and other organisms (Wearden & McShane, 1988). A third
class of dependent variable requires participants to reproduce a given time
period. The experimenter could present a time interval of a certain duration,
perhaps 2 minutes, without telling the participants the number of minutes that
had passed. The participants would then be asked to match the duration
of the interval presented previously.
Finally,
a comparison procedure might be used. One procedure would be to present
two different durations and ask a person to identify which of the two was longer. The
two-alternative forced choice method could also be used. Using this method,
two different durations could be presented (A and B) and then a duration (X)
could be presented and the observer asked to label the final duration (X) as
either A or B.
The estimation
and reproduction approaches can be applied in experimental situations in which
participants expect to make time judgments or are surprised by being asked
to make time judgments. For example, Brown and Stubbs (1988) asked some
undergraduates to listen to several musical selections and to pay close attention
to the selections because of a subsequent questionnaire; no mention was made
of duration. Other undergraduates were asked to remove their watches
and to listen to the same selections in an effort to estimate their durations. Just
as Montare found that feedback about accuracy improves timing judgments, Brown
and Stubbs found that people are more accurate when they know that they will
be judging duration.
Studies
of time typically involve levels of time in the independent variable. We
have already seen that some studies require people to judge the duration of
fairly long time periods, such as hours. In other research, such as that
of Montare (1985; 1988), much shorter durations are used (4 or 12 secs). Generally,
people tend to overestimate brief intervals and underestimate longer intervals
(Zakay, 1990). Further, researchers believe that longer intervals — beyond
5 secs — involve memory (Fraisse, 1984).
• Consistent with the results reported above, Crystal (2006) argues that time is not perceived in a linear fashion. That is, one minute will not appear to be one sixtieth of an hour. Moreover, there is not a simple linear translation of perceived time into actual time. Crystal discusses the multiple-oscillator theory of timing, the broadcast theory of timing, and the stochastic counting cascades approach -- all of which are consistent with nonlinear representation of time.
Events
that occur during the interval being judged have a major influence on duration
estimation. For example, stimulus intensity is important. Fraisse
(1984) concludes that more intense sounds and lights are judged longer than
less intense stimuli. This phenomenon is particularly true for vision.
Stimulus
complexity also influences duration estimation. Poynter and Homa (1983)
presented flashing lights, which flashed on and off in either a simple, regular
pattern or a more complex, irregular pattern. Using the reproduction
technique of duration estimation, participants provided longer estimates for
the more complex patterns. Furthermore, when participants look at a display
of dots, the perceived duration depends upon the number of dots and the velocity
with which the dots are rotated. The greater the number of dots (Mo,
1975) or the faster the speed of rotation (Tayama, Nakamura & Aiba, 1987),
the longer the time interval seems to be.
Duration
estimates also depend upon whether the interval is segmented or unsegmented. Poynter
(1983) prepared two kinds of tape recordings. Both consisted of 27 nouns
and the names of 3 U.S. presidents, and each recording lasted 170 seconds. However,
in the unsegmented recording, all 3 presidents' names appeared first, followed
by the 27 nouns. In the segmented recording the three presidents' names
appeared in positions 10, 20, and 27, thereby creating three segments, or parts,
in the recording. Poynter found that the unsegmented recording was judged
to be shorter than the segmented recording.
Recall the
filled space-open space illusion. Do you think that a duration will seem
longer if it is filled or empty? Ornstein (1969) proposed that a filled
interval should appear to be longer, and some data support his position. As
we'll discuss in the next section, the activities with which a person fills
a time period are also thought to influence time perception. However,
there are other data that suggest that filled intervals are not always perceived
as being longer. Jones and Boltz (1989) argue that the expectancies created
by the information filling an interval are more important than the absolute
quantity of information filling the interval. For instance, songs that
ended unexpectedly early were judged to be shorter in duration. So time
perception is influenced by several higher-level processes, including expectations,
consistent with Theme 4.
Most studies
of time perception don't specifically involve auditory stimuli, but it is clearly
the case that time is crucial for audition. In fact, durations that would
not be perceived by our visual system have profound implications for our auditory
system. You might assume, therefore, that the perceived duration of auditory
stimuli would differ from the duration of visual stimuli. However, Schab
and Crowder (1989) found little or no difference in the accuracy of judgments
of intervals greater than 1 sec that were presented visually or auditorily.
Music represents
one type of auditory stimulus for which timing is crucial (Jones, 1990). The
timing with which the notes are played determines the tempo,
or overall pace of the piece of music (slow or fast). Just as Andrea
Halpern (1989) found that people had good memories for the typical pitch of
familiar songs, she also found that people remember the tempos of familiar
songs, although they were tolerant of both faster and slower tempos (Halpern,
1988).
Musicians
can maintain identical tempos and still change the internal temporal organization
of a song, called meter or rhythm. If
you've heard the same melody played as rock and reggae or jazz, then you know
the importance of rhythm. Even the melody itself is strongly determined
by timing. The melodies of two of the songs of The
Music Man — "Seventy-Six
Trombones" and "Goodnight My Someone" — are composed of
virtually identical notes played with substantial timing differences, such
that the two songs do not sound at all similar.
Notice,
then, that stimulus characteristics can have an important influence on duration
estimates. A time period is judged longer if it is intense, complex,
or segmented. A time period marked by auditory stimuli is judged no more
accurately than a time period marked by visual stimuli. Some evidence
suggests that a filled time period is perceived as longer than an empty time
period, although it appears that this might well be due to expectations derived
from the information filling the time period.
Activities During a Time Period
The activities
of the person during the time interval being judged typically interact with
the contents of the duration, making the distinction between these two areas
somewhat arbitrary. Generally, you can think of the activities of the
observer as requiring greater or lesser amounts of cognitive effort. Often
the contents of the duration produce these differing attentional demands. Some
stimuli require more cognitive processing, and we may judge time on the basis
of the amount of cognitive "work" required of a person during an
interval (Luce, 1984). The important factor, apparently, is not the
complexity of particular stimuli presented, but the complexity of the task
in which a person is engaged (Block, 1990).
For instance,
one study asked people to estimate time passage, in number of seconds, for
a tone sounded while they were performing another task (Tsao, Wittlieb, Miller & Wang,
1983). When the other task was extremely demanding, they were more likely
to underestimate time. For example, a 63-second interval was estimated
as 38 seconds when the other task was extremely demanding, in contrast to 49
seconds when people were performing no other task.
Rather than
use different competing tasks, Brown and West (1990) had people perform simultaneous
duration judgments. The letters A, B, C, and D could appear in one of
the four corners of a computer screen for durations between 6 and 16 seconds. Each
letter would be on the screen for a different duration, and each would start
and stop at different times. People who were asked to keep track of all
four letters were much less accurate in their time estimates than people asked
to keep track of only one letter, providing further evidence for the position
that timing performance is disrupted with increasing attentional demands.
Two proverbs
emphasize the impact of a person's activities on time perception. You've
heard the proverb, "A watched pot never boils." This saying
has inspired several studies to determine whether people overestimate time
when they are waiting for an event. Cahoon and Edmonds (1980) told participants
in their study that the experiment would start after a delay; the experimenter
said he would return later. One group was told to call the experimenter
when the water in a glass coffee pot started to boil, whereas a control group
did not receive these instructions. In both cases the experimenter returned
4 minutes later and asked the participants to estimate how long he had been
gone. The duration estimates were significantly longer for participants
in the "watched-pot" group. Note that these results are consistent
with the hypothesis that filled time intervals appear to be longer than equal
unfilled intervals.
Contrast
these results with another proverb, "Time goes quickly when you're having
fun." This proverb suggests that filled time intervals can appear
to be shorter than unfilled intervals — if the task is a pleasant one.
Thayer and
Schiff (1975) asked female participants to estimate duration in a neutral condition
and then in an experimental condition in which they gazed at another person. This
other person was either smiling or scowling. The duration of the interval
was either 12 or 36 seconds, and participants were asked to reproduce the time
interval on a masked stopwatch. The time estimates were significantly
longer when the face was scowling than when it was smiling.
Thayer and
Schiff studied perceived duration when the contents were pleasant or unpleasant,
but what about the duration spent waiting for a pleasant or unpleasant event? Does
the time spent waiting for the trip to the dentist appear to be shorter or
longer than the time spent waiting for a vacation trip? Edmonds, Cahoon,
and Bridges (1981) found that the duration spent waiting for a positive experience
appeared longer than the duration spent waiting for a negative experience.
The activities
in which a person is engaged also interact with the type of study being conducted. As
Block (1990) says, "Experienced duration depends on variables such as
the amount of attention to temporal information, whereas remembered duration
involves contextual changes in memory" (p. 30). Thus, you might
expect the activities of an experiencer of time to be more of a factor when
the person knows that they are going to have to judge the duration of a forthcoming
interval.
So the perception
of time is a complex process involving several interrelated factors. As
a means of organizing the information on time perception, we have chosen to
focus on the framework proposed by Block (1990). Our brief review of
the field suggests that individual differences are substantial in time perception,
and that characteristics of the person judging time intervals has an impact
on time perception. How a researcher chooses to design a time perception
study also appears to have an impact. The structure of the central task
in which people are engaged, as well as any peripheral tasks they have to perform,
seem to have an impact on time perception. Further, in keeping with Theme
4 of this text, our sense of time certainly involves higher-order processes,
as indicated by the importance of learning and attentional demands.
1. Four factors appear to influence time perception: characteristics of
the time experiencer, time-related behaviors and judgments, contents of a
time period, and activities during a time period.
2. Time is of greater concern to different cultures and different groups
within the same culture. Nonetheless, all people have a number of internal
processes that follow circadian rhythms, suggesting the presence of an internal
biological clock.
3. In time perception research, one might choose a dependent variable
from among several options: (a) time estimation, using common units (mins,
secs), magnitude estimation, or rating scales; (b) time production; (c) time
reproduction; and, (d) comparisons of time intervals.
4. The contents of a time period influence duration estimates; a time
period is judged longer if it is intense, complex, and segmented. Some
evidence suggests that a filled time period is perceived as longer than an
empty time period, although it appears that this might well be due to expectations
derived from the information filling the time period.
5. Activities of the participants influence duration estimates; a time
period is judged less accurately if people are performing other tasks simultaneously. Time
appears to pass more quickly if people are waiting for an unpleasant event,
or if the situation in which they are engaged is pleasant.
Adams, D. (1979). The hitchhiker’s guide to the galaxy.
New York: Harmony Books.
Block, R. A. (1990). Models of psychological time. In R. A. Block (Ed.), Cognitive
models of psychological time, (pp. 1-35). Hillsdale, NJ: Erlbaum.
Brown, S. W., & Stubbs, D. A. (1988). The psychophysics of retrospective
and prospective timing. Perception, 17, 297-310.
Brown, S. W., & West, A. N. (1990). Multiple timing and the allocation of
attention. Acta Psychologica, 75, 103-121.
Cahoon, D., & Edmonds, E. M. (1980). The watched pot still won’t boil:
Expectancy as a variable in estimating the passage of time. Bulletin of the
Psychonomic Society, 16, 115-116.
Campbell, S. S. (1990). Circadian rhythms and human temporal experience. In R.
A. Block (Ed.), Cognitive models of psychological time, (pp. 101-118).
Hillsdale, NJ: Erlbaum.
Crystal, J. D. (2006). Sensitivity to time: Implications for the representation
of time. In Comparative cognition: Experimental explorations
of animal intelligence.
E. A. Wasserman & T. R. Zentall (Eds.)., (pp. 270-284.) New York: Oxford.
Edmonds, E. M., Cahoon, D., & Bridges, B. (1981). The estimation of time
as a function of positive, neutral, or negative expectancies. Bulletin of
the Psychonomic Society, 17, 259-260.
Fraisse, P. (1984). Perception and estimation of time. Annual Review of Psychology, 35,
1-36.
Halpern, A. R. (1988). Perceived and imagined tempos of familiar songs. Music
Perception, 6, 193-202.
Halpern, A. R. (1989). Memory for the absolute pitch of familiar songs. Perception & Psychophysics, 17,
572-581.
Jones, M. R. (1990). Musical events and models of musical time. In R. A. Block
(Ed.), Cognitive models of psychological time, (pp. 207-240). Hillsdale,
NJ: Erlbaum.
Jones, M. R., & Boltz, M. (1989). Dynamic attending and responses to time. Psychological
Review, 96, 459-491.
Joubert, C. E. (1984). Structured time and subjective acceleration of time. Perceptual
and Motor Skills, 59, 335-336.
Levine, R. V. (1988). The pace of life across cultures. In J. E. McGrath (Ed.), The
social psychology of time: New perspectives, (pp. 39-60). Newbury Park,
CA: Sage.
Levine, R. V. (1990). The pace of life. American Scientist, 78,
450-459.
Luce, R. D. (1984). Time perception: Discussion paper. Annals of the New
York Academy of Sciences, 423, 78-81.
Mo, S. S. (1975). Temporal reproduction of duration as a function of numerosity. Bulletin
of the Psychonomic Society, 5, 165-167.
Montare, A. (1985). Learning effects of knowledge of results upon time estimation. Perceptual
and Motor Skills, 60, 871-877.
Montare, A. (1988). Further learning effects of knowledge of results upon time
estimation. Perceptual and Motor Skills, 66, 579-588.
Ornstein, R. E. (1969). On the experience of time. Hammandsworth, England:
Penguin.
Poynter, W. D. (1983). Duration judgment and the segmentation of experience. Memory & Cognition, 11,
77-82.
Poynter, W. D., & Homa, D. (1983). Duration judgment and the experience of
change. Perception & Psychophysics, 33, 548-560.
Schab, F. R., & Crowder, R. G. (1989). Accuracy of temporal coding: Auditory-visual
comparisons. Memory & Cognition, 17, 384-397.
Tayama, T., Nakamura, M., & Aiba, T. S. (1987). Estimated duration for rotating-spot-pattern. Japanese
Psychological Research, 29, 173-183.
Thayer, S., & Schiff, W. (1975). Eye-contact, facial expression and the experience
of time. Journal of Social Psychology, 95, 117-124.
Tsao, Y., Wittlieb, E., Miller, B., & Wang, T. (1983). Time estimation of
a secondary event. Perceptual and Motor Skills, 57, 1051-1055.
Wearden, J. H., & McShane, B. (1988). Interval production as an analogue
of the peak procedure: Evidence for similarity of human and animal timing processes. The
Quarterly Journal of Experimental Psychology, 40B, 363-375.
Zakay, D. (1990). The evasive art of subjective time measurement: Some methodological
dilemmas. In R. A. Block (Ed.), Cognitive models of psychological time,
(pp. 59-84). Hillsdale, NJ: Erlbaum.
More Recent Material
• Scientific American (Sept. 2002) issue focuses on time, with an article by Antonio Damasio, "Remembering when" (66-73) and by Carol Ezzell, " Clocking cultures" (74-75). [Apparently re-issued with changes in 2006 as a "Special Edition"]
