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Ch. 28 Nervous Systems
Taylor - Campbell Biology: Concepts & Connections 10th Edition
Taylor, Simon, Dickey, Hogan10th EditionCampbell Biology: Concepts & ConnectionsISBN: 9780136538783Not the one you use?Change textbook
All textbooksTaylor, Simon, Dickey, Hogan 10th EditionCh. 28 Nervous SystemsProblem 8
Chapter 28, Problem 8

A proposal to test an SSRI in a large number of individuals with depression was submitted to the FDA. Through random assignments, half of the patients would be controls, receiving nothing at all, and half the patients would receive the drug in pill form. Patients in both groups would note changes in their own mood in a daily journal. What flaw(s) do you note in this experimental design?

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1
Identify the purpose of the experiment: The goal is to test the effectiveness of an SSRI (Selective Serotonin Reuptake Inhibitor) in treating depression. This requires a well-designed experiment to ensure valid and reliable results.
Recognize the importance of a control group: While the experiment includes a control group, the flaw lies in the fact that the control group receives 'nothing at all.' This can lead to biased results because the placebo effect is not accounted for. A proper control group should receive a placebo pill that looks identical to the SSRI pill but contains no active drug.
Evaluate the method of data collection: Patients are asked to note changes in their mood in a daily journal. This self-reporting method can introduce subjective bias, as individuals may interpret their mood changes differently or inconsistently. A more objective measure, such as standardized mood assessment scales administered by professionals, should be included.
Consider random assignment: Random assignment is correctly used to divide patients into groups, which helps reduce selection bias. However, the experimental design should also ensure that participants and researchers are blinded to group assignments (double-blind study) to prevent bias in treatment administration and data interpretation.
Address sample size and diversity: The proposal mentions a 'large number of individuals,' but it does not specify whether the sample is representative of the population with depression. Ensure that the sample includes diverse demographics (age, gender, ethnicity, etc.) to make the findings generalizable.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Control Group

A control group is essential in experimental design as it serves as a baseline to compare the effects of the treatment. In this case, the control group receives no treatment, allowing researchers to determine if changes in mood are due to the SSRI or other factors. Properly establishing a control group helps eliminate bias and ensures that the results are attributable to the drug being tested.
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Random Assignment

Random assignment is a technique used to ensure that each participant has an equal chance of being placed in either the experimental or control group. This process minimizes selection bias and helps ensure that the groups are comparable at the start of the experiment. In this study, random assignment is crucial for validating the findings and ensuring that any observed effects are due to the SSRI rather than pre-existing differences between participants.
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Self-Reporting Bias

Self-reporting bias occurs when participants provide subjective assessments of their mood, which can be influenced by their expectations or beliefs about the treatment. In this study, relying on patients to note changes in their mood in a journal may lead to skewed data, as those receiving the SSRI might report more positive changes simply because they expect the drug to work. This bias can compromise the validity of the study's conclusions.
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Related Practice
Textbook Question

Joe accidentally touched a hot pan. His arm jerked back, and an instant later, he felt a burning pain. How would you explain the fact that his arm moved before he felt the pain?

a. His limbic system blocked the pain momentarily, but the important pain signals eventually got through.

b. His response was a spinal cord reflex that occurred before the pain signals reached the brain.

c. Motor neurons are myelinated; sensory neurons are not. The signals traveled faster to his muscles.

d. This scenario is not actually possible. The brain must register pain before a person can react.

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Textbook Question

Which division of the autonomic nervous system would you expect to be activated if a person heard an intruder at the front door?

a. Parasympathetic

b. Sympathetic

c. Enteric

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Textbook Question

Anesthetics block pain by blocking the transmission of nerve signals. Which of these three chemicals might work as anesthetics? (Choose all that apply and explain your selections.)

a. A chemical that prevents the opening of voltage-gated Na+ channels in membranes

b. A chemical that inhibits the enzymes that degrade neurotransmitters

c. A chemical that blocks neurotransmitter receptors

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Textbook Question
Using microelectrodes, a researcher recorded nerve signals in four neurons in the brain of a snail, called A, B, C, and D in the table below. A, B, and C can all transmit signals to D. In three experiments, the animal was stimulated in different ways. The number of nerve signals transmitted per second by each of the cells is recorded in the table. Write a short paragraph explaining the different results of the three experiments.

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Textbook Question
Design an experiment with a group of taxi drivers in a new city to examine the role of neuroplasticity on learning. Assume you have the ability to image their brains to measure changes in the volume of gray matter.
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