Understanding Psychology (10th Ed)

(a)
(b)
(c)
FIGURE 6 
In the Müller-Lyer illusion (a), the vertical line on the left appears shorter than the 
one on the right, even though they are identical in length. One explanation for the Müller-
Lyer illusion suggests that the line on the left (with arrow points directed outward) is 
perceived as the relatively close corner of a rectangular object, such as the building corner in 
(b), and the line on the right (with the arrow points directed inward) is interpreted as the 
inside corner of a rectangular object, such as the room extending away from us (c). Our 
previous experience with distance cues leads us to assume that the outside corner is closer 
than the inside corner and, consequently, that the inside corner must therefore be longer.
Exploring
D I V E R S I T Y
Culture and Perception
FIGURE 7 
The “devil’s tuning fork” has 
three prongs . . . or does it have two?
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134 Chapter 
4 
Sensation and Perception
the world is put together and the way we perceive it. Our view of the world is very 
much an outcome, then, of fundamental psychological factors. Furthermore, each 
person perceives the environment in a way that is unique and special (Knoblich & 
Sebanz, 2006; Repp & Knoblich, 2007).
SUBLIMINAL PERCEPTION
Can stimuli that we’re not consciously aware of change our behavior? In some 
ways, yes. 
Subliminal perception refers to the perception of messages about which we have 
no awareness. The stimulus could be a written word, a sound, or even a smell that 
activates the sensory system but that is not intense enough for a person to report 
having experienced it. For example, in some studies people are exposed to a descrip-
tive label—called a prime —about a person (such as the word smart or happy ) so briefl y 
that they cannot report seeing the label. Later, however, they form impressions that 
are infl uenced by the content of the prime. Somehow, they have been infl uenced by 
the prime that they say they couldn’t see, providing some evidence for subliminal 
perception (Greenwald, Draine, & Abrams, 1996; Key, 2003). 
Although subliminal messages (which social psychologists refer to as priming ) 
can infl uence behavior in subtle ways, there’s little evidence that it can lead to 
major changes in attitudes or behavior. Most research suggests that they cannot. 
For example, people who are subliminally exposed to an image of a Coke can and 
the word “thirst” do later rate themselves as thirstier, and they actually do drink 
more when given the opportunity. However, they don’t particularly care if they 
drink Coke or some other liquid to quench their thirst (Dijksterhuis, Chartrand, 
& Aarts, 2007). 
In short, although we are able to perceive at least some kinds of information of 
which we are unaware, there’s little evidence that subliminal messages can change 
our attitudes or behavior in substantial ways. At the same time, subliminal percep-
tion does have at least some consequences. If our motivation to carry out a behav-
ior is already high and the appropriate stimuli are presented subliminally, 
subliminal perception may have at least some effect on our behavior (Abrams, 
Klinger, & Greenwald, 2002; Pratkanis, Epley, & Savitsky, 2007; Randolph-Seng & 
Nielsen, 2009).