LAB 7: THE SCIENTIFIC METHOD

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1 LAB 7: THE SCIENTIFIC METHOD Making an observation and asking an interesting question The first steps in the scientific method include making an observation, doing some background research on the topic, and then identifying an interesting question based on your observation. Observations may arise from reading or from first-hand experience. For example, you may have watched your dog frequently urinate while you're on walks. This leads to the question: Why does my dog urinate when we're on walks? There are many possible explanations for this behavior. Among the possibilities are that the dog avoids urinating in its own space (your yard), that there is something physiological about walking that stimulates urine production, or that that urination is a way of scentmarking territories, just to name a few. ACTIVITY I: CRICKET BEHAVIOR OBSERVATIONS For this activity, you will do some preliminary observations on crickets to become familiar with their behaviors and to help you develop a question that you would like to test. Crickets have become a model organism for a wide range of studies, including studies on aggression, territoriality, sexual behavior, development, and communication. Working in groups of 2-3, determine an area of cricket behavior that you are interested in investigating for this experiment. At the front of the classroom you will find an array of materials that you can use, as well as male and female crickets of various sizes, stages of development, wing morph (long or short wing), and hunger (some have been starved for several days, others have been provided unlimited access to food). For this portion, you will need a plastic cage and a stopwatch, as well as 1 or 2 crickets. Choose crickets appropriate for what you are interested in testing. For example, if you want to investigate sexual behavior, you should take a male and a female. Alternatively, if you want to investigate male-male competition, you may want to place two males in together. If you want to determine how hunger affects activity budgets, you will need a single cricket and a piece of food. Do not let these examples limit what you investigate, be creative! If you choose to put two crickets in together, make sure to mark one of them on their pronotum using a paint pen so that you can tell the difference between them. Once you have your materials, begin by you and your group members observing the same crickets, at the same time, for 5 full minutes. Do not talk you re your partners during this time (you will compare notes later), but focus on recording all the cricket behaviors you observe. If you have 2 crickets in together, write down which cricket did each behavior. For example, if you see one cricket move, then groom itself, the move again, you can write #1 move-groom-move.

2 Observed cricket behaviors When you are done with the 5 minutes of observation, answer the following questions: How did your observations compare to those made by your partners? Did you agree/disagree on what to name certain behaviors? Did you see any patterns of behavior that you can use to develop an interesting question about cricket behavior?

3 Formulating a hypothesis To take the possible explanations for your observations and determine which answer is mostly likely correct, you need to formulate the explanations into hypotheses. A hypothesis is basically a prediction about the outcome of an experiment. A typical hypothesis will be in the following general form: If then because. You can use this format to develop hypotheses that relate directly to your experiment. For example, If we go on a walk, then my dog will frequently urinate because urination is a way of scentmarking territories. More formally, a hypothesis is a statement of an experimental result that supports an answer to the question. It is usually paired with a null hypothesis, which does not support that answer. The null hypothesis (H o ) is the expectation that there is no effect of whatever we're testing. The alternative hypothesis (H a ) is the "positive" result - for example, a difference between a control and on experimental group of animals. So, taking the dog urination example a step further, you might decide that you can gain insight into the larger question by collecting dog urine and pouring measured amounts at the base of trees. Your hypotheses would then be: H o : If the urine from another dog is present on a tree, then it will have no effect on the urination behavior of my dog because urination is not used to mark territories. H a : If the urine from another dog is present on a tree, then it will increase the likelihood of my dog urinating at the base of the tree because urination is used to mark territories. You can see that this hypothesis is much narrower than the original question, and also much more specific than the various answers we listed. The hallmarks of a good hypothesis are that: (1) the hypothesis is directly testable and (2) the result of testing the hypothesis will give you insight into the original question. One very important pitfall to avoid is deciding what you think the answer to the question is before you test any hypotheses. Good scientists never set out to "prove" anything. One of the intriguing aspects of science is that the results of experiments may be entirely unexpected. Being open to unexpected results, and to modifying established theories if newly collected data does not fit them, is a key characteristic of good scientists.

4 ACTIVITY II: FORMULATING A HYPOTHESIS OF CRICKET BEHAVIOR Develop a null and alternative hypothesis on the cricket behaviors you observed in the previous section (Remember to use the proper format If then because ). H 0 : H a : Developing your experimental design Testing your hypothesis can involve observation, experimental manipulation, or both. The key here is to develop a way to test it that is feasible, without too much expense or time. You should make sure that you have enough individuals to properly test your hypothesis, and you should measure something that will provide quantitative information to analyze. A good experimental design isolates the effect that a single variable (i.e., the independent variable) has on a second variable (i.e., the dependent variable) while holding all other variables constant. It is important to attempt to control any other variables that may confound your results. For example, you might hypothesize that plants grow more when exposed to sunlight, and test your hypothesis by comparing growth of plants on sunny and cloudy days. Unfortunately, cloudy days are also likely to be cooler and more humid than sunny days, so any difference in the growth might be related to temperature or humidity, rather than sunlight. To test that sunlight is a cause of plant growth, you would need to carefully control all other variables that might influence growth. In animal behavior, it is often difficult to maintain precise control over the myriad of internal (physiological and genetic) and external (social and ecological) factors that might affect behavior; consequently tests of causation are sometimes elusive in studies of behavior. ACTIVITY III: DESIGNING AN EXPERIMENT ON CRICKET BEHAVIOR What is the independent variable (manipulated variable) that you are testing? What is the dependent variable you are testing (response variable)?

5 What variables must be kept constant for this to be a controlled experiment? List the materials you will need to complete this experiment. Outline the procedure you will follow to conduct this experiment. Be specific. Conducting the experiment An experiment always looks straightforward on paper, but in practice there are snags and unanticipated problems. Animal subjects are not always cooperative and they behave in unexpected ways. Unexpected contingencies mean that projects often take more time than originally planned. Invariably, as you start work on your project, you will get bogged down in the nitty-gritty details of your experiment and may lose sight of just what it was that you were trying to find out. You should frequently refer back to your original hypothesis to ensure that your project remains on track even if you need to modify your experiments as you proceed. Be sure to include sufficient replication in your study so that you may draw statistically meaningful conclusions from your data. First, maintain consistency in the methods you use. This is especially important if more then one person is collecting the data. If two people collect data differently, than differences in the results may be due to biases in data collection and not due to the intended treatment effects. Data collected using variable methods or inconsistent units of quantification are extremely difficult to analyze.

6 ACTIVITY IV: CONDUCTING AN EXPERIMENT ON CRICKET BEHAVIOR Create a data table to display your results Use the data you have collected to create a graph. Include a title, axis labels, units, and a scale.

7 Drawing conclusions Scientists draw conclusions by examining the data from their experiment, evaluating it critically, and relating it back to their original hypotheses. The results from an experiment may support the hypothesis, support only part of the hypothesis, or refute the hypothesis. In all cases, scientists must reflect on their data to determine if the experiment was in any way flawed, such that the results should not be trusted. Reasons for flaws are numerous, including poor inter-observer reliability, lack of appropriate controls, the presence of confounding variables, or incorrect assumptions. If the experimental design and data collection are not flawed, scientists can then use their results to draw conclusions about their hypotheses and suggest future avenues of research that are needed to understand the broader research question at hand. Conclusions can be surprising and unexpected, and the completion of one experiment often results in the start of several more. Being open to unexpected results, modifying hypotheses, and investigating these new hypotheses using additional experiments are key characteristics of good scientists. ACTIVITY V: DATA INTERPRETATION AND CONCLUSIONS What does your data show? Be specific and descriptive. Did the results of your experiment validate you hypothesis? What other variables might affect the cricket behaviors that you investigated? If you could do this experiment over, what would you change? If you could do a follow-up experiment, what would you test next?