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Exploring Research Methods & Design
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AP Science Practice

Earlier in this module, we explored the positive effects of touch. Development psychologists report that touch enhances the
development of premature infants. To test the effects of touch therapy on physical development, researchers randomly assigned
hospitalized premature infants to one of two groups. The experimental group had their limbs massaged for 15 minutes, 3 times
a day, for 10 days. The control group did not receive massages. On average, the massaged preemies gained 47 percent more
weight and went home 6 days sooner than did the control group preemies. As a result of this and other studies, many neonatal
intensive care units now provide touch therapy to premature infants.
• Explain which research design is being employed in the study described here (correlational or experimental).
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• Explain how the use of random assignment strengthened this study.
• Can you draw a cause-and-effect conclusion from this study? Explain.
• Imagine that you are on an institutional review board. Which questions would you ask the researchers to ensure that the
Copyright © Bedford, Freeman & Worth Publishers.
study follows ethical guidelines?
Remember, you can always revisit Unit 0 to review information related to psychological research.

Module 1.6d REVIEW

1.6-12 What are the four basic touch sensations, the aromas that interact with information from the taste
and how do we sense touch? receptor cells of the taste buds.
• There are no basic sensations for smell (olfaction). From
• Our sense of touch consists of four basic sensations — the top of each nasal cavity, some 20 million olfacto-
pressure, warmth, cold, and pain — that combine to pro- ry receptor cells for smell send messages to the brain’s
duce other sensations, such as “itchy” or “wet.” olfactory bulb, and then onward to the temporal lobe’s
primary smell cortex and to the parts of the limbic system
1.6-13 What biological, psychological, and social- involved in memory and emotion.
cultural influences affect our experience of pain?
How do placebos and distraction help control pain? 1.6-15 How do we sense our body’s position and
movement?
• The biopsychosocial perspective views our perception of
pain as the sum of biological, psychological, and social- • Position and motion sensors in muscles, tendons, and
cultural influences. joints called proprioceptors enable kinesthesis, our sense
• Pain reflects bottom-up sensations and top-down cognition. of the position and movement of our body parts.
• The gate-control theory of pain suggests that a “gate” in • We monitor our head’s (and thus our body’s) position
the spinal cord either opens to permit pain signals trav- and movement, and maintain our balance, with our ves-
eling up small nerve fibers to reach the brain, or closes to tibular sense, which relies on the semicircular canals and
prevent their passage. vestibular sacs to sense the tilt or rotation of our head.
• Pain treatments often combine physical and psychologi-
cal elements. Placebos can diminish the central nervous 1.6-16 How does sensory interaction influence our
system’s attention and responses to painful experiences. perceptions, and what is embodied cognition?
Distraction can activate neural pathways that inhibit pain
and increase pain tolerance. • Our senses influence one another. This sensory interaction
occurs, for example, when the smell of a favorite food
1.6-14 In what ways are our senses of taste and amplifies its taste.
smell similar, and how do they differ? • Embodied cognition is the influence of bodily sensations,
gestures, and other states on cognitive preferences and
• Taste and smell are both chemical senses. judgments.
• Taste (gustation) is a composite of six basic sensations —
sweet, sour, salty, bitter, umami, and oleogustus — and of

156 Unit 1 Biological Bases of Behavior

03_myersAPpsychology4e_28116_ch01_002_163.indd 156 15/12/23 9:27 AM