Knowledge Base

Notes

• For Twitching and Hopping, which is an event with no duration, the Behavior duration threshold and the Calculate statistics for options are not available.
• For more information on Behavior recognition in EthoVision XT, see the following paper:
  
  van Dam, E., J.E. van der Harst, C.J.F. ter Braak, R.A.J. Tegelenbosch, B.M. Spruijt, L.P.J.J. Noldus (2013). An automated system for the recognition of various specific rat behaviours. Journal of Neuroscience Methods (2), 214–224.
  http://dx.doi.org/10.1016/j.jneumeth.2013.05.012
• The Behavior decision method acts as a filter to ignore samples for which the behavior is associated with a low probability, making it easier to extract more reliable data. By default, EthoVision XT uses the original scores (thus no filtering based on probabilities). See the figure below for an example. Top: The probability of Grooming, and another behavior plotted against time (for simplicity, other behaviors are ignored here). Bottom: When defining Grooming in the Analysis profile, consider the following options:
  • With Default selected, Grooming occurs every time its probability exceeds the probability of any other behavior (default behavior recognition).
  • With Probability greater than 50% selected, Grooming is limited to the samples for which its probability is higher than 50%. The higher the value, the more conservative the definition.
• The Behavior duration threshold acts as a filter to ignore short transitions between states. For example, if the behavior Grooming is scored for 0.8 s and you select a Behavior duration threshold of 1.0 s, the Grooming state does not exceed that threshold, and is therefore excluded from analysis.
• For all behaviors but Twitching and Hopping, the percentage statistics are calculated including Unknown. For example, when Grooming lasts 30 seconds, Not Grooming 1 min 30 s, and Unknown 30 s, then the Cumulative Duration within Track (%) for Grooming is 30/150 = 20%. If you want to exclude Unknown from the percentage, in the Data profile make two nesting intervals, one with [behavior name] and the other with Not [behavior name], then combine the two Nest boxes in parallel. Next, in the Analysis profile specify the behavior and its statistic, Cumulative Duration within Nesting (%). In the example above, the result would be 30/120 = 25%.
• The duration of the behaviors may not add up to 100% of the track duration, also when including Unknown. This could result, for example, when you filter a behavior using a probability threshold. When visualizing behaviors, samples filtered out appear as gaps between behaviors.
• When you specify a Behavior probability threshold for one behavior, the other behaviors (which are mutually-exclusive by definition) are not re-calculated according to that setting. Depending on the value of the probability threshold, the behavior may become overlapping with other behaviors. For example, if you select a probability threshold of 15% for Grooming, some parts of the track may be scored as Grooming where also Eating was scored based on the default settings (see below). To prevent this from happening, either use Default or choose the same probability threshold for all behaviors.
  
  Below: Event plots of behaviors Grooming and Eating. Top: Behavior probability. Middle: Grooming is defined with a Behavior probability greater than 15%. Bottom: Eating is defined with Default probability settings, and is scored for most of the time due to the high probability (see the probability plot). As a result, Grooming is partially overlapping with Eating, although the two behaviors are supposed to exclude each other. With default settings, Grooming would not be scored.

See Also

• How Behaviors Are Scored in Behavior Recognition

Source: EthoVision XT 19 Help, Noldus Information Technology