Lecture 5Observation and Experiment

WANG Huaping

Philosophy Department, Shandong University

ContentsContents

Description2

Problems4

Observation31

Experiment 33

Observation is the foundation of science.

Experiments are observations made

under controlled conditions.

Observation and experiment – twin

pillars of the scientific method.

The Scientific Enterprise

Observation

The scientific method requires observations of nature to formulate and test hypotheses. It consists of these steps:

1.Asking a question about a natural phenomenon

2.Making observations of the phenomenon

3.Hypothesizing an explanation for the phenomenon

4.Predicting a logical consequence of the hypothesis

5.Testing the hypothesis by an experiment, an observational study, or a field study

6.Creating a conclusion with data gathered in the experiment.Observation plays a role in the second and fifth steps of the

Scientific Method.

Observation

Observation means studying and gathering information on an activity: of what happens, what your object of study does or how it behaves. Observation is visual: you use your own eyes, perhaps assisted with a camera or other recording instrument. Descriptive observation means that you do not wish to modify the activity in any way, you just want to register it such as it would take place without your presence.

Observation

Observations by different observers must be comparable. The idea of measurement evolved to satisfy this requirement. Measurement consists of using observation to compare the thing being measured to a standard; an artifact, process or definition which can be duplicated or shared by all observers, and counting how many of the standard units are comparable to the object. Measurement reduces an observation to a number which can be recorded, and two observations which result in the same number are equal within the resolution of the process.

Observation

Senses are limited, and are subject to errors in perception such as optical illusions. Scientific instruments were developed to magnify human powers of observation, such as weighing scales, clocks, telescopes, microscopes, thermometers, cameras, and tape recorders, and also translate into perceptible form events that are unobservable by human senses, such as indicator dyes, voltmeters, spectrometers, infrared cameras, oscilloscopes, interferometers, Geiger counters, x-ray machines, and radio receivers.

Observation

Observation ought to be close.

Observation ought to be objective.

Observation ought to be systemic.

Observation is selective.

Description

Scientists who conduct experiments must first study and describe the system with which they experiment, researchers who initiate comparative studies need descriptive data regarding the population they are investigating, and scientists who build models must have an accurate representation of the system they are modeling.

All research methods involve data gathering and hypothesis development and testing, and the descriptive method is no different. This method usually involves an initial observation and detailed description of some phenomenon.

Description

Description involves the systematic observation and cataloging of components of a natural system in a manner that can be utilized and replicated by other scientists.

Description is commonly used as a research method to explain unique natural systems (such as in ecology or chemistry), large-scale phenomena (such as in astronomy), or past events (such as in geology or forensic science).

Description

Description sometimes serves as starting point of a research.

Murder of Kitty Genovese:

Genovese had driven home from her job working as a bar manager early in the morning of March 13, 1964. Arriving home at about 3:15 a.m. she parked in the parking lot about 30m from her apartment’s door, located in an alley way at the rear of the building. As she walked towards the building she was approached by Winston Moseley.

Description

Frightened, Genovese began to run across the parking lot and towards the front of her building. Moseley ran after her, quickly overtook her and stabbed her twice in the back. Genovese screamed, "Oh my God, he stabbed me! Help me!" Her cry was heard by several neighbors but, on a cold night with the windows closed, only a few of them recognized the sound as a cry for help. When one of the neighbors shouted at the attacker, “Let that girl alone!” Moseley ran away and Genovese slowly made her way toward the rear entrance of her apartment building. She was seriously injured, but now out of view of those few who may have had reason to believe she was in need of help.

Description

A witnesses observed Moseley enter his car and drive away, only to return ten minutes later. In his car, he changed to a wide-brimmed hat to shadow his face. He systematically searched the parking lot. Eventually, he found Genovese who was lying, barely conscious, in a hallway at the back of the building where a locked doorway had prevented her from entering the building. He proceeded to further attack her, stabbing her several more times. Knife wounds in her hands suggested that she attempted to defend herself from him. While she lay dying, he raped her. He stole about $49 from her and left her in the hallway. The attacks spanned approximately half an hour.

Description

The New York Times published an article bore the headline “Thirty-Eight Who Saw Murder Didn't Call the Police.” Later investigation by police and prosecutors revealed that approximately a dozen (but almost certainly not the 38 cited in the Times article) individuals nearby had heard or observed portions of the attack.

Inspired by the article, social psychologists John Darley and Bibb Latané started a research leading to the so called “the bystander effect” or “Genovese syndrome”.

Description

The bystander effect or Genovese syndrome is a social psychological phenomenon that refers to cases where individuals do not offer any means of help in an emergency situation to the victim when other people are present. The probability of help has in the past been thought to be inversely related to the number of bystanders; in other words, the greater the number of bystanders, the less likely it is that any one of them will help. The mere presence of other bystanders greatly decreases intervention.

Description

There are two main reasons to explain the bystander effect. According to a basic principle of social influence, bystanders monitor the reactions of other people in an emergency situation to see if others think that it is necessary to intervene. Since everyone is doing exactly the same thing (nothing), they all conclude from the inaction of others that help is not needed. This is an example of pluralistic ignorance or social proof. The other major obstacle to intervention is known as diffusion of responsibility. This occurs when observers all assume that someone else is going to intervene and so each individual feels less responsible and refrains from doing anything.

Description

Feminist psychologist Frances Cherry has suggested the interpretation of the murder as an issue of bystander intervention is incomplete. She has pointed to additional research such as that of Borofsky and Shotland demonstrating that people, especially at that time, were unlikely to intervene if they believed a man was attacking his wife or girlfriend. She has suggested the issue might be better understood in terms of male/female power relations.

Experiment

The observer listens to nature. The experimenter questions and forces her to reveal herself.

Georges Cuvier

Experiment

Experimentation is a research method in which one or more variables are consciously manipulated and the outcome or effect of that manipulation on other variables is observed.

Experiment: Cause/Effect

• Follows the steps of the scientific method

• Has controlled variables

• Has a definite purpose, can have a timeframe.

• Does have a manipulated variable (therefore, does have a responding variable).

Basic format: “If I do this (independent variable), then this (dependent variable) will happen.

Independent variable (IV): the experimenter changes this variable; should only change one thing per experiment.

Dependent variable (DV): value depends on the independent variable; its measure determines if hypothesis was correct or incorrect.

All other conditions should remain constant in all trials so that any changes to the DV can be attributed to variation in the IV.

Experiment

Procedure should be clear and easy to reproduce by others.

Experimental group: independent variable is altered.

Control group: standard of comparison; “no treatment” group.

Only one factor is changed at a time in the experimental group, keeping all other conditions constant.

Experiment

Qualitative data relies on the senses and reveals

changes in behavior. Quantitative data relies on measurable facts and

figures. Best to examine the data as a whole. Analysis of a set of data has significant advantage

over contrasting the results between two data points. Ability to find suspect data is greatly enhanced. If there is a choice as to order, you may wish to

obtain the most critical data first.

Experiment

Based on analysis of results, accept or reject the

hypothesis.

Accept: test it again using a different variable.

Reject: form a new hypothesis and go through the

process again.

Recommend further experimentation and

possible improvements to the procedure.

Publish your results.

Experiment

The earliest documented scientific experiment was devised by a Persian scientist ibn al-Haytham, also known as Alhazen.

According to the ancient thought, vision is possible because light rays emanated from the eye illuminating objects around us. Alhazen doubted the idea. He decided to carry out experiments of refute it. In one of the experiments, he stood in a darkened room with a small hole in one wall. Outside of the room, he hung two lanterns at different heights.

Experiment

Alhazen observed that the light from each lantern illuminated a different spot in the room, and each lighted spot formed a direct line with the hole and one of the lanterns outside the room. He also found that covering a lantern caused the spot it illuminated to darken, and exposing the lantern caused the spot to reappear. Thus, Alhazen provided some of the first experimental evidence that light does not emanate from the human eye but rather is emitted by certain objects (like lanterns) and travels from these objects in straight lines.

Experiment

Alhazen’s experiment may seem simplistic

today, but his methodology was ground-

breaking: he developed a hypothesis based on

observations of physical relationships (that

light comes from objects), and then designed

an experiment to test that hypothesis.

Experiment

The Michelson–Morley experiment：

Famous Experiment

A controlled experiment generally compares the

results obtained from an experimental sample against

a control sample, which is practically identical to the

experimental sample except for the one aspect whose

effect is being tested (IV). A good example would be

a drug trial. The sample or group receiving the drug

would be the experimental one (treatment group);

and the one receiving the placebo would be the

control one.

Controlled Experiment

Between 600-500 BC the biblical Daniel carried out

probably the first recorded experiment in history with

a control group. He wanted to follow God’s ideal

diet, a vegetarian diet. But, his Babylonian

supervisor thought it would be unhealthy. So, Daniel

proposed a 10 day experiment with Daniel and his

friends eating a vegetarian diet with simple water and

the control group (the other students) eating the royal

diet (which was heavily meat based and included

wine).

Controlled Experiment

Daniel and his friends were found to be healthier

than the control group after the 10 days. They

continued following this diet for the next 3 years

while studying diligently all the wisdom of

Babylon. Upon examination at the end of the

course, Daniel and his friends impressed the king

far more than any others.

Controlled Experiment

Natural experiments rely solely on observations of

the variables of the system under study, rather than

manipulation of just one or a few variables as occurs

in controlled experiments. To the degree possible,

they attempt to collect data for the system in such a

way that contribution from all variables can be

determined, and where the effects of variation in

certain variables remain approximately constant so

that the effects of other variables can be discerned.

Natural Experiment

Surrogate Mother ExperimentMonkeys were removed from their mothers and placed in

a room with two different fake mothers: one made of wire

that was designed to give milk and another that was made of

a soft material but did not give milk. The monkeys preferred

the soft mother and those that spent more time cuddling with

it grew up to be more healthy. This experiment showed that

love – demonstrated by physical body contact – is a more

important aspect of the mother-child bond than the

providing of basic needs.

Natural Experiment

Gneezy and Rustichini conducted, at the end of the 1990s, a field experiment involving 10 kindergarten schools in Haifa. The experiment was meant to test the deterrence hypothesis, widespread in legal studies and the basis of some psychological work on behavior modification: the introduction of a penalty, ceteris paribus, reduces the occurrence of the behavior subject to the fine. Day-care centers normally face the common problem of parents arriving late to collect their children: the experiment testing the deterrence hypothesis consisted in introducing a fine in six of the ten day-care centers.

Field Experiment

A flat rate fine was imposed on those parents that arrived ten or more minutes late. The other four centers, where everything was left unchanged, served as a control group. The treatment (a monetary sanction) was assigned to six of the day-care centers that were identical, in every relevant respect, to the other day-care centers that served as the control group. Parents in the treatment group were informed by the managers of the day-care centers of the introduction of the fine but were unaware that they were being the subjects in an experiment.

Experiment

The number of parents coming late was then measured and found significantly higher in the treated population: the study showed that in those centres where the fine was introduced there was an increase in the number of parents coming late, thus contradicting the deterrence hypothesis.

Gneezy and Rustichini favor an explanation in terms of incomplete contracts and information: in the absence of a fine, parents cannot be certain about the consequences of misbehavior and so tend to comply to the rule of arriving in time for fear of the unspecified consequence.

Experiment

Once a fine is imposed, they can be certain of the perceived cost of their behavior on the part of the managers of the school, and so some parents that were restraining themselves from arriving late will now do so, knowing that they will be fined by the specified amount. The fine thus serves as a price that conveys information on the cost of their behavior, and arriving late becomes a “commodity”.

Identify the IV and DV in this experiment.Identify the IV and DV in this experiment.Do you think this experiment has any problem?Do you think this experiment has any problem?

Experiment

It is pointed that observation is theory-laden, that is, Sense data are molded by different theories, interpretations and intellectual constructions. Gazing at the same object by two people does not necessarily mean that they see the same thing.

Our senses provide so much information to our Our senses provide so much information to our mind that it must be filtered. We only see certain mind that it must be filtered. We only see certain aspects of reality; the dominant scientific paradigm aspects of reality; the dominant scientific paradigm determines which.determines which.

Problems

Rabbit or duck?

Problems

Young girl?

Or old women?

Man playing horn?

Or a woman’s silhouette?

A face of a nativeAmerican?

Or an Eskimo’s back?

One problem encountered throughout scientific fields is that the observation may affect the process being observed, resulting in a different outcome than if the process was unobserved. This is called the observer effect. For example, it is not normally possible to check the air pressure in an automobile tire without letting out some of the air, thereby changing the pressure. However, in most fields of science it is possible to reduce the effects of observation to insignificance by using better instruments.

Problems

Can you remember???

What experiments have you done in What experiments have you done in

Science subjects since S1?Science subjects since S1?

Thank you！