Science Writing ARCHIVED Pandemic Version

How to Quantify Behavior

Behaviors are traits in much the same way as morphological or physiological attributes can be traits. Some behaviors may be innate, while others can be learned or altered during an individual’s life. Behaviors can be influenced by the environment, by other animals, or by internal physiology. Understanding how behaviors function, how they influence an organism’s ecological interactions, and now how natural selection acts on behavior are all fascinating fields of inquiry. The study of animal behavior is known as ethology, and people who focus on behavior are ethologists.

The first steps to studying behavior are to

(1) define the behavior and

(2) quantify it.

Defining behaviors

Behavior is complex. Even basic activities like “foraging” can be broken down into many smaller components -- searching, smelling, touching, moving, etc. Ethologists begin by breaking complex behaviors down into discrete and readily identifiable components.

For example, Kelly Lambert and her colleagues wanted to understand how previous experiences influence rats’ ability to find food in complex environments. To test this, they trained a group of rats with food-finding exercises, and then compared their ability to navigate a maze to that of control rats that had not received training. They predicted that the un-trained rats would be slower in the maze, and that they would be exhibit more signs of stress or frustration. To quantify this, the researchers defined 10 specific behaviors, shown in Table 1.

Notice how each behavior is small and carefully defined. “Rearing” is distinguished from “freezing”. “Jumping” is different from “Exploring”. Most of these behaviors are so well-defined that you can probably already imagine what they look like, even if you’re not a rat expert (granted, a few like “stereotype” would make more sense after watching rats for awhile and seeing that they sometimes rapidly thump their back legs).

Table 1: Behaviors used in Lambert et al. rat study. Lambert et al. 2014 Frontiers in Behavioral Neuroscience

Here’s another example: Ellen Blesdoe and Daniel Blumstein wanted to know how sparrows respond to predators. To test this, they observed sparrow behavior in response to recordings that simulated hawk calls, which they broadcast on speakers. Table 2 shows the behaviors they defined.

Notice that they distinguished between multiple types of locomotion -- walking, hopping, and foraging are distinct behaviors. They also distinguish between two types of vocalization.

How do you know what behaviors to quantify?

By spending time watching your organism! The first step for any behavioral study is observational, deciding what behaviors to quantify. You will engage in this process for Phase I of your pilot experiment.

Table 2: Behaviors used in Blesdoe and Blumstein sparrow study. Blesdoe and Blumstein 2014 Current Zoology

Quantifying Behaviors

Once we have defined a series of discrete behaviors, we can use these definitions to quantify behaviors. For this, we use a tool called an ethogram.

The ethogram (also called a behavior scan sheet) is a record of which specific behaviors were exhibited during an observation period. It is used to quantify the frequency and duration of specific, well-defined movements or actions.

Each column represents a behavior, and each row represents a time interval. The length of the time interval could range from seconds to minutes or even hours depending on the organism and the behaviors being studied.

A sample ethogram:

You will use a behavior scan sheet to quantify the frequency and duration of your chosen behaviors. In the scan sheet, each column represents a behavior, and each row represents a time interval. By keeping an ethogram, you can estimate how much time the animal engaged in each behavior by counting how many intervals it occurred in, and multiplying by the interval duration.

The length of the time interval should be appropriate for your organism and the behaviors being studied. The example shown here has 10 second intervals, but this could be far too short (or far too long) for your organism. Part of the planning, then, involves choosing an appropriate time scale -- 5 sec? 30 sec? 3 min? You should make this decision based on your organism, and how quickly it moves.

The other decision you’ll need to make is how long the total observation should last. 10 min? 20 min? 2 hrs?

Citations

Blesdoe, E.K. and Blumstein, D.T., 2014. What is the sound of fear? Behavioral responses of white-crowned sparrows Zonotrichia leucophrys to synthesized nonlinear acoustic phenomena. Current Zoology, 60(4), pp.534-541.

Lambert, K.G., Hyer, M.M., Rzucidlo, A.A., Bergeron, T., Landis, T. and Bardi, M., 2014. Contingency-based emotional resilience: Effort-based reward training and flexible coping lead to adaptive responses to uncertainty in male rats. Frontiers in Behavioral Neuroscience, 8, p.124.

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