Lecture Notes - 2 - May 16th

7/29/2019 Lecture Notes - 2 - May 16th

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Chapter 1 - Continued

THINKING CRITICALLY WITH

PSYCHOLOGICAL SCIENCE


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STATISTICS IN PSYCHOLOGICAL RESEARCH

Two Types

Statistics is theuse of mathematics to organize, summarize and interpret data.

1. Descriptive Statistics

Statisticsusedtoorganize and summarize data.

2. Inferential Statistics

Statisticsusedtointerpretdataand drawconclusions.


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For any given set of data, you want to look at its shape, center and spread.

Shape

Histogram for Quantitative Data

0

50

100

150

200

5 15 25 35

Frequency (f)

Age (years)

Age (years) f % cf % cf

30-39 1 0.4% 234 99.6%

20-29 147 62.6% 233 99.1%

10-19 86 3 6.6% 86 36.6%

! 235 100%



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Shape


0

50

100

150

200

5 15 25 35

Frequency (f)

Age (years)


30-39 1 0.4% 234 99.6%

20-29 147 62.6% 233 99.1%

10-19 86 3 6.6% 86 36.6%

! 235 100%



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Shape


0

50

100

150

200

5 15 25 35

Frequency (f)

Age (years)


30-39 1 0.4% 234 99.6%

20-29 147 62.6% 233 99.1%

10-19 86 3 6.6% 86 36.6%

! 235 100%



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Shape



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Measures of Central Tendency

1) Mode: the most frequently occurring score in a distribution

2) Median: the score that falls in the center of a distribution

3) Mean: the arithmetic averageofthe scores in a distribution



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Measures of Variability

1) Range: the diference betweenthe highest and lowest scores.

2) Standard Deviation:

A computed measure ofhow much on average the scores in a data set vary aroundthe meanscore.



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Standard Deviation-A Closer Look

-80 = -80 =


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Relatively Low Standard Deviation




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Relatively High Standard Deviation




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Shape



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Normal Distribution-A Closer Look

A normal distribution(curve) is asymmetric, bell-shaped curve that describes thedistribution of many types of data(heights, weights, grades...).


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Normal Distributions -A Closer Look

All normal distributions followthe empirical rule: approximately68% of the scoresfall within 1 standard deviation of the mean, 95% of the scores fall within 2

standard deviations of the the mean, and 99.7%

of the scores fall within 3 standarddeviationsofthe mean.


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Correlation

A correlation exists when two variables are related to each other.

Acorrelation may either be:

High School GPA College GPA Absences Test Scores

1 2.1 2.3

2 2.4 2.2

3 2.7 2.8

4 2.9 3

5 3.2 3.5

6 3.3 3.4

7 3.6 3.6

8 3.9 4

Student

1 10 25

2 8 45

3 7 65

4 6 67

5 5 70

6 4 80

7 3 85

8 1 99

Student

Positive Correlation Negative Correlation



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A Positive Correlation A Negative Correlation

High SchoolGPA

CollegeGPA

High SchoolGPA

CollegeGPA

Absences ExamScores

Absences ExamScores

2

2.5

33.5

4

2 2.5 3 3.5 40

25

5075

100

0 2 4 6 8 10

CollegeGPA

ExamScor

es

AbsencesHigh School GPA

Scatterplot Scatterplot


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Correlation Coecient

A correlation coecient (r) is a numerical index of the degree of relationship

between two variables.

It is a number between-1 and 1.

The sign+ or - indicates directionof the relationshipThe number indicates strengthof the relationship.



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1. Descriptive StatisticsCorrelation and Causation

Correlations allow us to predict the value of one variable based on knowledge of theother variable.

What do correlations allow us to do?

2

2.5

33.5

4

2 2.5 3 3.5 40

25

5075

100

0 2 4 6 8 10

CollegeGPA

ExamScor

es

AbsencesHigh School GPA


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Correlation and Causation

What do correlation not allow us to do?

Correlations do not tell uswhether a cause-efect relationship exists between twovariables.

For example: Does low self-esteem cause depression?

Correlation

Does Not

Imply

Causation!


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Marijuana and Driving Performance: Results

Marijuana Group Placebo Group

Mean No. of Collisions 3.6 2.1

What is the likelihood that our observed diference may have simply come aboutby chance?

Inferential statistical procedures allow us to answer thisquestion.

If the likelihood that our observed diference may have simply come about bychance isvery low(p-value < .05), then we say it is statistically significant.


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But be careful:

And remember, even if our result is significant, in order to generalize back

to the population of interest (say to all students), what do we need?


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Chapter 2

THE BIOLOGY OF THE

MIND


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THE BIOLOGY OF THE MIND


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NEURONS AND NEURAL COMMUNICATION

The Neuron: The Basic Unit of the Nervous System


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The Neuron at Rest


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The Active Neuron

The neuron receives excitatoryand inhibitory inputs from many neurons. When the excitatoryinputs minus the inhibitory inputs exceeds a threshold(about -55 mv), an action potential resultsat the axon hillock.

++

+


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The Active Neuron

Voltage-gated ion channels openand positive ions (Na+) rush in. These positive ions cause voltage-gated ion channels to open along adjacent sections. In this way, the action potential propagatesdown the length of the axon. But it does so in only one direction!Why?

Na+Flows in

K+ Flowsout


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The Active Neuron

This refers to the minimum time after an action potential during which another action potentialcannot begin. It occurs because voltage-gated ion channels become briefly inactive after anaction potential(1 to 2 ms). This iswhy an action potential only moves in one direction!

The Refractory period


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The Active Neuron

The myelin sheath is an insulating sheath, derived from glial cells (support cells of the nervous system),that encases some axons. It is interrupted at intervals byshort unmyelinated sections of axon, callednodes of Ranvier. The myelin sheath greatly speeds up neural transmissionas an action potentialneed only be generated at the nodes.

The Myelin Sheath


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The Active Neuron

This refers to the fact that an action potential either occurs or it does not , and if it occurs then it is ofa fixed amplitude; a neuron conveys information about the strength of a signal by varying thefrequency at which it fires action potentials.

The All-or-None Law


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Neural Communication

Once the action potential arrives at the terminal button, vesicles in the button fuse with themembrane and releases a neurotransmitter into the synapticcleft. The neurotransmitter difusesacross the cleft and binds to receptor site located on the dendrites of another neuron in a lock-and-key fashion.


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Neurotransmitters may be excitatory (depolarize the membrane) or inhibitory (hyperpolarizethe membrane).


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++

+

Neurotransmitters may be excitatory (depolarize the membrane) or inhibitory (hyperpolarizethe membrane).


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Serotonin Pathway Dopamine Pathway


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Agonists and Antagonists

Agonists are chemicals that are similar in structure to, and thus mimic the actionof, natural neurotransmitters.


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Antagonists are chemicals that are similar in structure to naturalneurotransmitters, but they are not so similar that they activate the receptor;instead, they just block it.

Agonists and Antagonists


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http://www.youtube.com/watch?v=gETYSWeLlYY&playnext=1&list=PLF1339A8AF95249FF&feature=results_main


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THE NERVOUS SYSTEM - AN OVERVIEW

Central

Nervous

System

(CNS)

Peripheral

Nervous

System

(PNS)


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THE NERVOUS SYSTEM

Peripheral Nervous System

1. Somatic Nervous System-controls bodys skeletal muscles(voluntary)

2. Autonomic Nervous System - controls glands and smooth muscles(involuntary)

Consists of motor neurons (that send information to muscles and glands) andsensory neurons (that send information from sensory organs) thatcommunicate withthe CNS.

Two Divisions


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THE NERVOUS SYSTEM

Autonomic Nervous System-A Closer Look

1. Sympathetic Nervous System- arouses body, mobilizes its energy

2. Parasympathetic Nervous System- calms body, conserves its energy

Two Divisions

Fight orFlight

Rest andDigest


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THE NERVOUS SYSTEM

Central Nervous System

Spinal Cord -A Simple reflex


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THE NERVOUS SYSTEM

Central Nervous System

The Brain


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BRAIN FUNCTION - BEGINNINGS

PhrenologyFranz Joseph Gall, a German physician, (around 1808) reasoned brain areas shouldgrow when exercised, like muscles.

Shape of skullshould reflect size of underlying brain tissue: bumps on the skullthus reflect a persons personality traits.

1758-1828

Franz Joseph Gall


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PhrenologyThis assumption was wrong: 1)bumps on skull do not reflect size of underlyingbrain tissue, and 2)assignment of traits to brain areas arbitrary.

Nevertheless, Gall was the first person to take seriously the idea, in a very tangibleway, that thebrain was the seat of the soul.

1758-1828

Franz Joseph Gall

BRAIN FUNCTION - BEGINNINGS

Lecture Notes - 2 - May 16th

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