Figure 17-2. Linear Velocity as a Function of Time for 128 Paths 

 of the Fairy Shrimp Eubranchipus Vernalis in Polarized Light. 



In principle, all behavioral variables which may be investigated using the 

 Bugsystem can be generated by simple arithmetic transformation of series of X 

 and Y coordinates. Greaves (4) has discussed the computation of certain 

 behavioral variables (viz., linear velocity, net to gross displacement ratio, 

 direction of travel and angular velocity) using arithematic operators 

 implemented within the prototype system. Such operators transform every 

 element of every data vector within a file, treating each vector as a separate 

 unit of data. The present Bugsystem is also provided with a wide selection of 

 simple arithematic operators. However, we have condensed the computation of 

 certain frequently calculated behavioral variables into single operators which 

 require path data as input. As an example, let us consider the RATE OF 

 CHANGE OF DIRECTION operator whose command syntax is illustrated by 

 the entry 



*RCDI BUGS.PA GUBS.RD nl . 



Every element in the resultant file "BUGS.RD" is the unsigned rate at which 

 the corresponding path changed its direction of travel at a given moment. RCD 

 is the absolute value of angular velocity expressed in degrees per second (The 

 parameter "nl" is the frame rate, required to convert from degrees per frame.) 

 The importance of this variable in ascertaining mechanisms responsible for 



266 



