Illusory Upward Self-Motion Results in a Decrease in Perceived Room Temperature

doi:10.4236/psych.2013.411118

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2013. Vol.4, No.11, 823-826

Published Online November 2013 in SciRes (http://www.scirp.org/journal/psych) http://dx.doi.org/10.4236/psych.2013.411118

Open Access 823

Illusory Upward Self-Motion Results in a Decrease in Perceived

Room Temperature

Takeharu Seno1,2,3, George H. Van Doorn4

1Institute for Advanced Study, Kyushu University, Fukuoka, Japan

2Faculty of Design, Kyushu University, Fukuoka, Japan

3Research Center for Applied Perceptual Science, Kyushu University, Fukuoka, Japan

4School of Applied Media and Social Sciences, Monash University, Melbourne, Australia

Email: [email protected], [email protected]

Received August 21st, 2013; revised September 22nd, 2013; accepted October 23rd, 2013

Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any

medium, provided the original work is properly cited.

Purpose: Stationary observers often experience illusory self-motion (vection) when they are exposed to

large patterns of optic flow. The effect of different temperatures on the strength of vection was investi-

gated. Method: Eleven participants were exposed to visual stimuli that induced illusory motion (up, down)

in three room temperatures (26˚C - 27˚C, 21˚C - 22˚C, 5˚C - 6˚C). Participants rated (a) the vection mag-

nitude, and (b) the room temperature (twice; before and after vection). Results: Upward vection was rated

as stronger than downward vection in the 26˚C - 27˚C temperature. In addition, after experiencing upward

and downward vection, subjective ratings of room temperature decreased and increased, respectively,

when the room temperature was 26˚C - 27˚C. This effect was not observed when the room was 5˚C - 6˚C.

Conclusion: These results suggest that a cross modal association exists between the direction “up” and

26˚C - 27˚C temperatures.

Keywords: Vection; Temperature; Vision; Illusory Self-Motion

Introduction

Exposure to a visual motion field that simulates the retinal

optical flow generated by self-movement commonly causes the

perception of the subjective movement of one’s own body. This

phenomenon is known as “vection” (Fischer & Kornmuller, 1930).

For example, when a stationary person observes a train begin-

ning to move, they are likely to perceive that they are moving

in the opposite direction to the motion of the train. This pheno-

menon is known as the “train illusion”, and provides a good

example of vection (e.g. Seno & Fukuda, 2012). Some recent

studies reported that vection can modulate aspects of perception

and cognition, e.g. daydreaming (Miles, Karpinska, Lumsden,

& Macra, 2010), attention (Seno, Ito, & Sunaga, 2011a), time

perception (Seno, Ito, & Sunaga, 2011b), perception of num-

bers (Seno, Taya, Ito, & Sunaga, 2011), and visual illusions

(Fukuda & Seno, 2011; Fukuda & Seno, 2012). Vection is also

affected by personality traits such as narcissism (Seno, Yamada,

& Ihaya, 2011). In this study, we assessed for the first time

whether vection can be modulated by temperature, or can have

a modulating influence on perceived temperature.

Soto-Faraco, Spence and Kingstone (2004) suggested that a

feature in one sensory modality can be associated with a feature

in another sensory modality, i.e. a cross-modal correspondence.

Although different sensory organs receive different inputs, in-

teractions between sensory modalities occur after these inputs

have been recoded at post-perceptual levels (Marks, 2004); re-

coding activates a representation that captures elements of each

input that are common across modalities (Martino & Marks,

2000). Consequently, reaction times (RTs) to a simultaneously

presented high-pitched tone and a light coming from above

might be shorter, for example, than RTs to a low-pitched tone

and a light coming from above; the recoded inputs of the for-

mer pair share the post-perceptual format “high”, whereas the

later do not.

Similar to Mark’s (2004) work, Seno, Ito, Sunaga, Hasuo,

Nakajima and Ogawa (2011) recently proposed a consistency

hypothesis that predicts that visually-induced self-motion will

be enhanced when inputs from one (or more) of the non-visual

senses are consistent with visual simulation. Consistent with the

predictions of this hypothesis, somatosensory stimulation gen-

erated by adding air-flow to a stationary observer’s face sig-

nificantly (p < .05) enhanced visually-simulated forward mo-

tion (Seno, Ogawa, Ito, & Sunaga, 2011). In addition, vection

has been facilitated by vibrations on the body and auditory cues

that are consistent with visual rotation (Riecke, Schulte-Pelkum,

Caniard, & Bülthoff, 2005; Riecke, Feuereissen, & Rieser, 2008).

Crossmodal correspondence, or consistency, seems to be non-

arbitrary and accumulated through repeated exposure to pairs of

stimuli (Williams & Bargh, 2008). As we go through life expe-

riencing wind against our face, for example, it becomes paired

with forward motion.

This idea can be applied to temperatures and spatial direc-

tions (up/down) which may be semantically associated in eve-

ryday language (e.g. “hot air rises”). If a correspondence exists

between “hot” temperatures and “upward” direction (and vice

versa for “cold” and “down”) then vection may be influenced

by temperature; specifically, upward vection would be stronger

T. SENO, G. H. VAN DOORN

when the temperature of a room is hotter than usual, and vice

versa for colder temperature. In addition, illusory change in

room temperature may arise as a result of perceiving vection.

Thus, we tested the following hypotheses:

H1: In a 26˚C - 27˚C room, upward vection will be stronger

than illusory self-motion in other directions.

H2: Subjective ratings of room temperature will be hotter af-

ter experiencing upward vection, and cooler after downward

vection.

Method

Participants

Eleven volunteers (seven females) took part in the experi-

ment. The participants had a mean age of 24.8 years (SD = 3.7

years). All participants had normal or corrected-to-normal vi-

sion and none of them reported visual or vestibular abnormali-

ties. The experiments were pre-approved by the ethics commit-

tee of Kyushu University, and written informed consent was

obtained from each subject prior to participating.

Materials and Stimuli

The up/down vection stimulus was a white vertical sinusoid-

dal grating whose luminance was horizontally modulated. Mo-

tion displays subtended a visual area of 72˚ (horizontal) × 57˚

(vertical) when viewed from 570 mm in front of a television

screen. Upward/downward vection was induced by moving the

grating (spatial frequency: .1 cycle/deg; mean luminance: 18

cd/m2; Michelson contrast: 80%) down/up, respectively, at a

speed of ~20 deg/sec. We used virtually continuous motion in

the minimum motion technique that was essentially the same as

that used in Cavanagh, MacLeod and Anstis (1987). Each up/

down motion stimulus consisted of 13 images presented se-

quentially and repeatedly. The gratings moved in only one di-

rection for the duration of each trial, which was fixed at 30 sec.

There was also a static (i.e. control) grating condition.

The experiment was conducted in a 7 m × 7 m × 2.6 m dark-

ened room. There were three room temperature conditions, i.e.

normal (21˚C - 22˚C), hot (26˚C - 27˚C), and cold (5˚C - 6˚C).

Room temperature was modulated and kept constant by the two

air conditioners. Room temperature was certificated by the ther-

mometer.

Procedure

Prior to the presentation of stimuli, participants were asked to

sit down; they remained seated for the entire experiment. Be-

fore each stimulus combination was presented (e.g. 5˚C - 6˚C

temperature/upward grating pattern) participants were asked to

estimate the room temperature to one decimal point (e.g. 23.5˚C).

They were also instructed to press a button during each trial if/

when they experienced vection, and were to keep the button de-

pressed for as long as the experience lasted. If vection ceased,

or became ambiguous, they were to release the button. Duration

and latency of vection were recorded as dependent variables.

Latency was defined as the time interval between the onset of

the visual stimulus and the time at which the participant pressed

the button. Duration was calculated as the total time that the

button was pressed until it was released.

Following the instructions a motion stimulus was presented.

After the 30 sec stimulus presentation period ended, and after

participants released the button to signify that vection had ceas-

ed, participants rated the strength of vection by verbally stating

a number from 0 (no vection) to 100 (very strong vection); the

experimenter recorded this number on a piece of paper. Par-

ticipants then estimated the room temperature again, and the dif-

ference between pre- and post-trial estimations was calculated.

There were two motion directions and three room tempera-

ture conditions. There were four trials per condition, and thus a

total of 24 trials per participant. The presentation order of trials

was randomized. Each temperature condition lasted approxi-

mately 20 mins. Thus the experiment had a total duration of ap-

proximately 60 mins for each participant. All conditions were

interior-group design.

It is known that vection can be modulated by an experimen-

ter’s instructions or demands (Palmisano & Chan, 2004). Thus,

we carefully instructed the participants regarding their task with-

out giving them any suggestion which may lead to a cognitive

bias about the consistency hypothesis. Furthermore, several con-

trol conditions were included in an attempt to negate potential

extraneous variables.

Results

A 3 (temperature: 21˚C - 22˚C, 26˚C - 27˚C, 5˚C - 6˚C) × 3

(grating motion: upward, downward, static) repeated-measures

ANOVA on subjective ratings of vection strength revealed a

significant main effect of temperature [F(2,20) = 21.62, p

< .0001, η2 = .16]. Vection was weaker in the 26˚C - 27˚C con-

dition than in the 21˚C - 22˚C and 5˚C - 6˚C cold conditions

(see Figure 1). This is supported by the duration and latency

data which were significantly shorter and longer, respectively,

in the 26˚C - 27˚C condition relative to the 21˚C - 22˚C and 5˚C

- 6˚C conditions [duration: F(2,20) = 6.83, p = .005, η2 = .06;

latency: F(2,20) = 13.62, p = .0002, η2 = .21].

The main effect of the grating motion was significant [mag-

nitude: F(2,20) = 66.62, p < .0001, η2 = .16; duration: F(2,20) =

86.29, p = .005, η2 = .70; latency: F(2,20) = 54.36, p < .0001, η2

= .55]. Bonferroni-corrected post-hoc tests revealed significant

differences between the static grating and the others (p < .05).

Importantly, the direction of illusory self-motion experienced

by each participant was consistent with previous research (e.g.

Seno, Ito, & Sunaga, 2009).

The interaction between temperature and grating motion was

significant [magnitude: F(4,40) = 9.36, p < .05, η2 = .10; dura-

tion: F(4,40) = 3.79, p < .05, η2 = .03; latency: F(4,40) = 12.19,

p = .002, η2 = .16]. Bonferroni-correct post-hoc comparisons

revealed that upward vection was stronger than downward vec-

tion in the 26˚C - 27˚C condition (p < .05), and thus H1 was

supported.

A second 3 (temperature) × 3 (grating motion) repeated-mea-

sures ANOVA on the difference between perceived tempera-

tures pre- and post-stimulus presentation revealed no significant

main effect of temperature [F(2,20) = 1.62, p = .22; η2 = .03]

(see Figure 2). The main effect of grating motion was signifi-

cant [F(2,20) = 7.17, p = .0045, η2 = .08]. Post-hoc tests

(Holm’s Sequentially Rejective Bonferroni Procedure) revealed

significant differences between down and the other two condi-

tions [up vs. down, t(10) = 2.98, p = .04; Cohen’s d = .73; down

vs. static, t(10) = 2.48, p = .03; d = .31]. There was also a trend

towards significance between the up and static conditions, t(10)

= 2.05, p = .06; d = .29. The interaction was significant [F(4,40)

= 2.64, p < .05, η2 = .12]. Bonferroni-corrected post-hoc com-

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T. SENO, G. H. VAN DOORN

Figure 1.

Strength of vection. The unit of measure-

ment for latency and duration were seconds,

while magnitude was a rating from 0 to 100.

There was no vection in any static condition,

and hence the “spaces” in the figures.

Figure 2.

The perceived change in temperature after vection.

parisons revealed that perceived room temperature was modu-

lated by motion stimuli only in the 26˚C - 27˚C condition (p

< .05).

Discussion

Vection refers to the experience of illusory self-motion in re-

sponse to large patterns of optic flow. The main issues explored

in this study were whether (a) vection is influenced by changes

in room temperature, and (b) perceived room temperature is

changed by experiencing vection. Remarkably, the interaction

between temperature and grating motion was significant, and

thus vection seems to be influenced by room temperature. Fur-

ther, and contrary to H2, upward vection produced a perceived

drop in room temperature and downward vection resulted in a

perceived rise, but only in the 26˚C - 27˚C condition.

We speculate that, as upward vection was stronger than

downward vection in the 26˚C - 27˚C condition, there is a cor-

respondence between heat and upward motion that exists in clo-

sed spaces, e.g. rooms and buildings where hot air rises. How-

ever, in the 5˚C - 6˚C condition, downward vection was not sig-

nificantly stronger than upward vection. It is somewhat surpris-

ing that an association exists only between 26 - 27˚C and “up”,

and not between 5˚C - 6˚C and “down”. Although speculative,

this unidirectional finding may be explained by the work of

Riecke et al. (2008) who showed that the possibility of actual

self-motion facilitates vection. In their experiment auditory cir-

cular vection was enhanced by suspending participants above

the ground. In our experiment, participants’ feet touched solid

ground and they, presumably, knew that actual “downward”

motion was impossible, whereas given the free space above each

participant’s head it was (theoretically) possible for them to

move up into this free space.

To examine this hypothesis, we conducted an informal ob-

servation with 4 naïve volunteers in which their feet were kept

off the ground, and thus upward and downward motion was

(theoretically) possible; we, again, measured strength of vection.

The results were similar to those of the main experiment, i.e.

upward vection was stronger than downward vection in the

26˚C - 27˚C condition. Thus, the idea that contact between

one’s feet and solid ground inhibits vection is not supported by

our informal observations. That said, even though the partici-

pants’ feet did not touch the ground, their buttocks did touch

the chair. Further experiments are planned to determine whe-

ther manipulating the procedure shows correspondence effects

in the other conditions. The current results suggest that illusory

self-motion is stronger when there is a correspondence between

two stimuli and one knows that physical motion is possible.

Contrary to H2, upward vection produced a perceived drop in

room temperature while downward vection resulted in a per-

ceived rise, but only in the 26˚C - 27˚C condition. It is possible

that participants were aware of the fact that hot air rises and,

after experiencing illusory self-motion in the 26˚C - 27˚C tem-

perature condition, they expected an increase in room tempera-

ture. As the actual temperature remained constant after experi-

encing vection, because no physical positional change took place,

there was a discrepancy between expected and actual room

temperatures, which resulted in the room being judged colder

than it actually was. However, given downward vection was

weaker than upward vection in the 26˚C - 27˚C and, here, down-

ward vection resulted in a perceived increase in room tempera-

ture, this explanation is speculative. It might be that the hot

temperature (26˚C - 27˚C) and vection stimuli used here contain

some unknown features that correspond, whereas the cold tem-

perature (5˚C - 6˚C) and vection stimuli did not. There is some

evidence (see Pilcher, Nadler, & Busch, 2002) that heat can be

more attention-getting than can cold and, as such, it may be that

a hotter room shifts attention to temperature, and thus partici-

pants became sensitive to it.

It is known that exposure to visual stimuli like those used

here can create nausea in participants, and common autonomic

reactions are cold sweating and reduced peripheral blood flow.

These reactions are especially common among healthy, young

people who do not suffer from vestibular disorders. These are

natural autonomic responses and a shift in the autonomic nerv-

ous system towards a sympathetic reaction. Although each ex-

Open Access 825

T. SENO, G. H. VAN DOORN

Open Access

826

perimental trial lasted only a short time, there were repeated

exposures and the autonomic response is quick, especially if

trials are repeated with short inter-trial intervals. That said, for

autonomic responses to have been a confounding variable the

reported influence of temperature on vection would have to be

explainable having found that autonomic responses occurred in

the 26˚C - 27˚C temperature/downward motion (upward vection)

condition but not in the 26˚C - 27˚C temperature/upward mo-

tion (downward vection) condition, and that this increased the

perceived strength of vection in the former condition. There is

no evidence to support such a view.

In conclusion, we have demonstrated the existence of a new

crossmodal correspondence, namely an association between tem-

perature and directional up; vection modulated perceived tem-

perature, and was modulated by actual temperature. As Parise

and Spence (2012) argue, this correspondence might reflect the

natural correlation between physical properties of the world, i.e.

warmer air moves upwards relative to cooler air.

Acknowledgements

This work is supported by the Program to Disseminate Ten-

ure Tracking System, MEXT, Japan.

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