The effect of moving air on detection of a 60-Hz electric field

Two potential mechanisms in detection of a 60-Hz electric field by albino rats were examined: field-induced movement of the vibrissae and field-induced vibration of the skin. Specifically, the experiment tested field detection in a moving stream of air designed to mask field-induced movement of the skin, fur, and vibrissae. Rats were trained to detect electric fields and were then tested at field intensities from 0-25 kV/m rms. As previously reported, rats demonstrate unmistakable behavioral evidence of field detection at all intensities above 7.5 kV/m. After establishing detection in still air, field detection was re-examined in moving air (average air velocity approximately 2.8-6.8 m/s). The primary result is that the wind produced no change in detection at field intensities above threshold (> 7.5 kV/m). Indeed, at these intensities detection was virtually identical in still and moving air. A secondary finding is that moving air produced statistically significant (P < .05) but apparently contradictory effects on detection when the field intensity was below threshold. On no-field trials the wind lowered scores (i.e., fewer presses on the field-off lever); however, on subthreshold field trials, the wind actually increased detection scores (i.e., more presses on the field-on lever). While this no-field and subthreshold field result is interesting and deserves further study, we place primary emphasis on the finding that, if the field was detectable in still air, it was also detectable in moving air. This result leads us to believe that movement of the vibrissae, fur, or skin is not likely to be the main mechanism of electric-field detection in our subjects.