Table 1.

Effects of head position and stimulus polarity on group mean magnitudes of individual response vectors measured from horizontal displacement of the trunk and horizontal ground reaction force

		Displacement (mm)		Force (N)
		Mean	s.d.	Mean	s.d.
Head right	Binaural L+R−	6.82	2.46	1.30	0.57
Bipolar (n= 10)	Monaural sum	9.69	3.18	1.68	0.71
		t9= 4.91	P < 0.001	t9= 3.32	P= 0.009
	Binaural L−R+	6.55	3.81	1.38	0.63
	Monaural sum	9.03	5.03	1.98	0.71
		t9= 4.42	P= 0.002	t9= 5.05	P < 0.001
Head forward	Binaural L+R−	7.36	3.57	1.44	1.01
Bipolar (n= 20)	Monaural sum	10.48	3.74	2.08	0.84
		t19= 6.96	P < 0.001	t19= 5.93	P < 0.001
	Binaural L−R+	6.53	3.18	1.40	0.69
	Monaural sum	8.92	4.10	1.85	0.66
		t19= 5.19	P < 0.001	t19= 3.82	P= 0.001
Head forward	Binaural L−R−	3.28	1.70	0.34	0.25
Monopolar (n= 10)	Monaural sum	3.48	2.13	0.47	0.23
		t9= 0.24	P= 0.813	t9= 1.01	P= 0.338
	Binaural L+R+	2.81	0.65	0.48	0.25
	Monaural sum	3.01	1.66	0.90	0.58
		t9= 0.36	P= 0.727	t9= 2.34	P= 0.044

Null hypothesis, response to stimulation of both labyrinths (binaural) has same magnitude as vector sum of component monaural responses, tested using the two-tailed paired t test. Probability less than 0.01 shown in bold. L = left labyrinth. R = right labyrinth. Positive and negative superscripts denote anode and cathode respectively. Head right, monopolar data from Experiment 1; head forward, bipolar data from Experiments 1 and 2; head forward, monopolar data from Experiment 2.