What visual representation is primarily used to illustrate changes in behavior over time?

The equal-interval line graph is particularly effective for illustrating changes in behavior over time because it allows for precise tracking of progress by plotting data points along a continuous scale. Each point on the graph represents a specific measurement at a certain time, and the connection between these points visually demonstrates trends, patterns, or fluctuations in the behavior being measured. This continuous representation makes it easier to see how behavior evolves, making it ideal for understanding data collected across different sessions or time periods.

The other visual representations, while useful in certain contexts, do not prioritize the same level of detailed time-based tracking. For instance, frequency charts display counts of behavior occurrences, but they do not effectively convey the temporal aspect. Scatter plots can show relationships between two variables but are less suitable for demonstrating changes over time. Bar graphs provide a comparison of variables at a single point in time rather than over an extended duration. Thus, the equal-interval line graph stands out as the most appropriate visual tool for depicting behavioral changes over time.