are selected using the terminal cursors. Thus, the ratio between the distances 

 separating the points in Bugspace and in physical space yields a factor or 

 proportionality between Bugwatcher units and conventional units of spatial 

 measurement (e.g., jum, mm, cm, etc.). 



Experimental Parameters and Experimental Variables 



Biological interpretation of behavioral data requires that the behavior of 

 organisms be related to experimental conditions prevailing at the time of 

 observation. Consequently, we have developed methods to associate 

 experimental parameters and experimental variables with sets of data. An 

 experimental parameter is a quantity characterizing a condition which is 

 constant throughout any given record but may vary from record to record 

 (e.g., temperature, concentration of a pollutant, etc.). Using the PARAMETER 

 operator, such numerical constants may be inserted into the set of attributes 

 belonging to each data vector. Parameters may be deleted, modified or listed. 

 They may be used to organize graphical displays (e.g., average linear velocity as 

 a function of temperature) or to modify the execution of certain operations. 



An experimental variable is a quantity whose value changes during a single 

 record. Times at which simple step changes in stimulus conditions (e.g., 

 switching a light on and off) occur may be indicated by the presence or 

 absence of tones stored on the audio track of a video tape. The Bugwatcher 

 possesses four tone generators to produce such temporal markers during the 

 course of an experiment; it also possesses external connections which allow the 

 simultaneous gating of laboratory apparatus. When the video tape is replayed 

 into the Bugwatcher these tones are detected. As discussed above, the second 

 attribute in each data vector sent to the computer contains four bits dedicated 

 to representing the presence or absence of the four tones. 



We are presently developing a technique which provides for the 

 representation of stimuli which vary continuously over time. The stimulus level 

 will be encoded by means of frequency modulation (fm) on the audio track of 

 the video tape. When the tape is replayed into the Bugwatcher the fm signal 

 will be digitized and represented with 10-bit precision by the fourth attribute 

 of each data vector sent to the computer. The APPEND operator wUl be 

 employed to extract this information from each data vector, scale it and store 

 as an equispaced time series. Again these data may be used to organize 

 graphical displays or they may enter into computations involving time series of 

 behavioral variables. One of us (Wilson) is preparing to employ this method to 

 investigate behavior evoked by rotation of the plane of polarized light. The 

 organisms swim beneath a polaroid filter whose angle is controlled by an analog 

 servomechanism. The filter may be rotated so as to describe quick jumps, 

 ramps, harmonics, etc. A signal directly proportional to the angle of the filter 

 will be encoded and analyzed. 



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