Time survived in all ages. Centuries later, psychology has

has always been one of the most mysterious and challenging aspects of life to
figure out. From physics to philosophy, we are still trying to define the
actual existence and meaning of time in our lives. Hard to be conceptualized,
it has been a great enigma for centuries now, rising numerous questions. Humans were aware of
different type of times long before they had even formulated the concept of
time itself (Roeckelein, 2008, p. 4). The first attempts to define and study
systematically- albeit naively and non-scientifically- the concept of time
sprang from the Ancient Greeks as early as 5th century B.C. (Hyland, 1994). The
Greek philosopher Aristotle was the first to ask from a psychological point of
view how we perceive time (Nichols, 1989). For Aristotle, time was a direct
sense perception that derived from the sentient faculty or soul as an immediate
function under the presentation of primary sensation or of memory and as
Nichols (1989, p.458) states, Aristotle’s perception of time was a remarkable
first exposition of time where its essential features have survived in all

Centuries later,
psychology has put much effort to describe and define time with different
terms. As far as cognitive and experimental psychology is concerned, many
researchers were interested in exploring the field of time perception (Wearden,
2016, p. 5-25). In the last century, Francois (1927) and Hoagland (1933) were
the first researchers to point out that our time judgments vary as a function
of internal and external contexts. This realization concluded in the idea of
subjective time, which is referring to our personal evaluation of time,
regardless the faithful reading of objective time, e.g., from a counter (Gil
& Droit-Volet, 2012). About thirty years later, in the early 1960s, one of
the today’s most known theories was proposed by the works of Creelman (1962)
and Treisman (1963), describing a model regarding a clock-like mechanism which
was established as “the internal-clock model”(Wearden, 2016, p.19-25). It was
later on developed into the scalar timing theory, or also referred to as the
scalar expectancy theory (SET; Gibbon, 1977; Gibbon, Church & Meck, 1984;
Church, 1984), which proposes
that duration discrimination and perception of time are results of an internal
clock, memory stores and a decision mechanism. The internal clock is composed
of three components: a pacemaker, a switch, and an accumulator. The pacemaker emits
pulses, which are sent to the accumulator through the switch. The switch has
the role of the pulses’ guard. This means that it is the one to control how
many pulses pass through by signaling the start and the end of the time of the
event. Then, the pulses proceed to the accumulator so as to be counted and then
converted into the perceived duration (Li & Yuen, 2015).

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A revised
theoretical framework for discussing time estimation based on the scalar-timing
model and on Treisman’s model was presented by Thomas and Weaver (1975), and
expanded by Zakay and Block (1995). They introduced attentional models of time
perception, which in more detail concern information-processing (IP) mechanisms
(Buhusi & Meck, 2005), such as the Attentional-Gate Model (AGM; Zakay &
Block, 1995). This model proposes that organisms distribute attentional
resources, which are drawn from the same pool, between all performing tasks and
that temporal processing in order to function optimally requires the most of attentional
resources. Consequently, when a non-temporal task is in need of more attention,
then fewer resources are available for the temporal one, and thus temporal
performance is impaired (Brule & Casini, 2001). As a result, fewer pulses
are accumulated and the duration is perceived as shorter. This hypothetical
cognitive model explains why durations seem shorter when more attentional
resources are allocated to non-temporal tasks (Brule & Casini, 2001; Zakay,
Nitzan, & Glicksohn, 1983).

Based on these
theories, recent studies acknowledge that time perception can be dramatically
affected by variations in external stimulation and by the cognitive state of
the individual (Droit-Volet & Meck, 2007). Hence, the present research’s
purpose is to study how time estimation is being altered by specific features
that may capture an organism’s attention. For that reason, we selected human
faces, which are largely known to attract human’s attention, as well as be
capable of attention capture (Langton et al., 2008) even if they are
task-irrelevant (Simpson et al., 2014). Preeminently, as it has been supported
by many researches, in comparison with neutral faces, faces that involve facial
movements, such as emotional expressions or gaze, tend to capture attention
even more (e.g., Vuilleumier, 2002).

More specifically,
a great number of studies have confirmed that people are highly sensitive to
gaze direction, an ability that emerges in the very early stages of childhood.
Young infants prefer to look at the eyes more than at other regions of the face
(Morton & Johnson, 1991) and by the age of 4 months can discriminate
staring from averted eyes (Vecera & Johnson, 1995). Furthermore, there is evidence
of an advantage on the perception of direct gaze that extends to the perception
of change in direct gaze implying that directly gazing at someone captures
attention more (Yokoyamaô et al., 2011). Eye contact and mutual gaze can
influence face processing, even for a single exposure of an unfamiliar face
(Vuilleymier et al., 2005) and facilitate understanding other persons, i.e.,
accessing relevant material in semantic memory (Macrae et al., 2002). As Emery
(2000) states from an evolutionary point of view, many species seem to perceive
eye gaze as a crucial social signal and additionally visual processing may have
become of vital significance due to its attribution in confronting
morphological, environmental and habitat changes throughout primate evolution.

Consequently, eye
gaze could be argued to play a significant role in capturing human attention
and as a result influence time estimation into perceiving shorter durations
than the actual duration presented. Accordingly, there are some supportive
evidence advocating interval underestimation for short durations, such as 1200
and 2400 ms, when there was stimulus of direct gaze in comparison with averted
gaze stimulus (Rouchitsas, 2015), as it could have been predicted by the
attentional-gate model. However, there are studies that yield opposite results,
where the direct gaze stimulus produced longer subjective duration responses
(Thones & Hecht, 2016). Notably, both the above-mentioned studies provide
only weak and task-dependent evidence for the influence of mutual gaze on
subjective time. Nevertheless, it is clear and fair to note that direct gaze
may indeed play a crucial role in changing the subjective duration of a
temporal interval that is present on the order of several seconds.

Even though
studies on time estimation and gaze direction are limited, much research has
been made concerning the interplay of emotional expression and mutual or
averted gaze. The way in which gaze direction influences emotion perception
actually depends on the specific type of emotion and the overall social context
in which it is placed. Adams and Kleck (2005) found that for some emotions,
such as joy and anger, direct gaze enhances perception, but for other emotions,
e.g., fear and sadness, averted gaze does. They assumed that this kind of
differentiation in enhancement happens because anger and fear indicate the
source of threat (i.e., as part of an early warning mechanism), whereas joy and
sadness may just be a social signal indicating a tendency for social

Additionally, in
another study angry faces were recognized as expressing more anger and that the
underlying emotion was judged as being more intense with a direct than with an
averted gaze, whereas the opposite effect was revealed for the emotion of fear (Sander
et al., 2007). Looking directly towards someone else can also elicit more
positive and arousing reactions than when looking away, perhaps due to the
perception of direct gaze as an affiliative signal (Hietanen et al., 2018;
2008). It has been shown that direct gaze is a sign indicating the other person
as trustworthy and truthful (Bayliss & Tipper, 2006) and it is also used in
functions such as the regulation of turn-taking in conversation, expressing
intimacy, and exercising social control (for a review, see Langton, Watt, &
Bruce, 2000). Both emotional expression and gaze behavior seem to influence
attention and communicate basic behavioral motivations to social approach or

In the
emotion-related domain, many studies have been executed appointing the huge
effect of emotion, in general, and of facial expressions, in particular, on
time estimation (for reviews, see Droit et al, 2007; Lake, 2016; Lake, Labar, &
Meck, 2016). However, even though cognitive variables such as emotion have been
shown to influence judgment of duration, this happens not entirely
systematically (Meck et al., 2003). Hence, some evidence suggested that not
only attention but also arousal play a crucial role in time perception by influencing
different parts of the internal clock (Gil & Droit-Volet, 2011). In more
detail, it has been proposed that arousal influences the operation of the
internal pacemaker by speeding up its rate of emitting pulses and subsequently
this increases the number of stored units in the accumulator (Gil & Droit-Volet,
2012). Consequently, the duration of emotionally loaded stimuli (e.g., facial
expressions) are being overestimated relative to neutral stimuli. Angrilli et
al. (1997) conducted a study in order to investigate the effects of arousal and
valence on time perception. They found that there was no main effect of arousal
or valence, but a significant interaction between those two variables. More
specifically, at low levels of arousal the duration of negative slides was
underestimated, while the duration of positive slides was overestimated. In
contrast, at high levels of arousal, positive slide duration was underestimated
relative to the duration of negative slides. A great deal of data has been
corroborative to this arousal-driven temporal distortions by indicating a
lengthening effect produced by the perception of emotional faces and especially
of angry expressions, which are considered as more arousing due to their life-
threatening meaning (Doi & Shinohara, 2009; Droit-Volet, Brunot, &
Niedenthal, 2004; Fayolle & Droit-Volet, 2014; Fayollea, Gil &
Droit-Voleta, 2015; Gil et al., 2011; Gil & Droit- Volet, 2012; Li et al.,

On the other hand,
the advocates of the attentional gate model suggest that time intervals should
be underestimated when emotional stimuli are present due to the fact that
attention is allocated from time estimation to the cognitive process of vital
importance signals (Brule et al., 2001; Zakay et al., 1983). Many studies have
highlighted through different types of examination (e.g., detection tasks or
Stroop-like paradigm) an automatic processing of emotional expression and a
spontaneous bias to orient attention towards threatening cues, e.g., angry
faces (Vuilleumier, 2002). Moreover, threatening stimuli not only capture
attention but also delay the disengagement of attention from it (Belopolsky,
Devue, & Theeuwes, 2011).Lui and her colleagues (2011) found supportive
evidence that perceived time was shorter when it was preceded by an emotional
as compared to a neutral distractor indicating that emotional experiences may
decrease temporal estimates. However, the most contemporary data propose a
combined mechanism, which involves both attention and arousal (see Figure 1).
Arousal seems to influence mostly the pacemaker rate and as Angrilli et al.
(1997) implicated this phenomenon occurs only for very short durations, less
than 1s, whereas changes in attention, as reported earlier, seem to affect the
activity of a switch or gate that influences the number of pulses collected in
the accumulator but for longer durations.


Figure 1. An oversimplified way of demonstrating the derived
of emotion mechanisms of arousal and attention, as modulatory factors on time


The aim of the
present study is to investigate and describe the temporal distortions in
subjective time, which occur as a result of gaze behavior and facial emotional
expressions. Two types of gaze were examined, direct gaze and averted to the
left gaze, as well as three facial expressions, anger, fear, and happiness
along with a neutral expression as baseline. Many previous studies presented a
serious limitation as far as the type of stimulus is concerned. They used
mostly static images (Angrilli et al., 1997; Bar Haim et al., 2010; Doi et al.,
2009; Droit- Volet et al., 2004; Droit- Volet et al., 2015a; Droit-Volet et
al., 2015b; Gil et al., 2011; Gil et al., 2012), which cannot fully reflect
real life situations. Under those circumstances, various problems emerge
concerning ecological validity because facial behavior is a combination of
dynamic information rather than static patterns of portrayed emotional
expressions (Krumhuber, Kappas, & Manstead, 2013). Hence, it is very
important the experimental variables to be to the greatest extent closer to
reality including all the dynamic aspects facial activation can provide, as an
attempt to imitate the complexity of actual social interactions of daily
experiences. Only a few recent studies have focused on the different outcomes
produced by morphing photographs and static displays of emotions on time
estimation, concluding in a possible enhancement of the lengthening effect when
the stimulus was to some extent more dynamic (Fayolle et al., 2014; Li et al.,
2015). Although the above-mentioned researches offered some interesting
results, it must be stated that the utilization of morphing photographs in grayscale
still undermines considerably the attempt to approach real-life perceived faces
due to the fact that morphing has been shown to result in less accurate effects
(Krumhuber et al., 2013). Conversely, our experiment contained validated colored
videos from trained actors (Van der Schalk, Hawk, Fischer, & Doosje, 2011),
in order to emulate as much as possible real experiences. Hence, our experiment
could be considered as original in attempting to research authentic dynamic
aspects of emotional expressions and gaze behavior on the perception of
temporal intervals.

Another essential
feature under consideration in studies of time perception is the temporal
procedure to be followed. Each estimation method varies in the use of different
cognitive processes and as a result it has been stated that different approaches
produce different outcomes (e.g., Gil et al., 2011). Henceforth, it is crucial
to choose if the duration judgments are prospective or retrospective as well as
to specify the exact method of examining interval timing. In our study, we used
the prospective paradigm, which refers to a situation in which a person is
aware, during a time period that he or she needs to estimate this duration. It
has been argued that prospective duration timing depends on attention demanding
processes (Zakay & Block, 2004). Accordingly, since our aim is to examine
the possible effects of attention on time estimation, prospective paradigm
appears to be the most appropriate method to be followed., One of the most
applied methods in literature of perception and processing of temporal
information in the field of prospective timing, especially regarding the
effects of facial expressions, is the temporal bisection paradigm (for a
review, see Kopec & Brody, 2010).As a temporal discrimination task,
participants are required to compare temporal stimuli to two reference stimuli,
”long” and ”short”, held in memory. It is a well-known and largely tested
temporal task which has though often yield mixed and ambiguous results (Wearden,
2016, p.72-73). For this reason, we selected this method to examine timing
judgments in our experiment in order to provide an additional insight for this
controversial task when investigating dynamic stimuli. Furthermore, it seems
like a logical application since our tested population involves only participants
of age which in a meta-analysis by Kopec and Brody (2010), has been shown that
individuals performing the bisection task should be only over 8 years old.

In summary, our
main goal in the present experiment is to study the interplay of emotion and
gaze on time estimation by the use of dynamic stimuli. If the arousal- driven
mechanism is correct, then we shall find supportive evidence to current
bibliography concerning emotion and overestimated time judgments. On the other
hand, if AGM models are accurate, it is our strong belief that both emotion and
direct gaze will produce significantly shorter subjective judgments.

a better legend this just shows the AGM and where arousal or attention is
expected to affect….and also provide the reference where you took this and made
your own graphic