Smooth pursuit gain during maintenance was not significantly different between relatives and community subjects. Pursuit gain in response to retinal motion (i.e., during initiation) and to extraretinal motion were examined. A repeated measures ANOVA revealed a four-way interaction involving Subject Source × SSP Status × Target Velocity × Pursuit Phase (i.e., initiation vs. mask), F(2,262)=3.12, p<.05 (see ). Separate repeated measures employing the MANOVA procedure with simple effects were conducted for initiation and mask pursuit gain. No significant main effects or interactions were found for pursuit gain during initiation. However, the analysis of pursuit gain during the mask (i.e., residual predictive pursuit gain) revealed a significant Subject Source × SSP Status × Velocity interaction, F(2,262)=4.84, p<.01. Lower order effects included a main effect of velocity, F(2,262)=71.51, p<.001. A simple effects analysis of the three-way interaction (examining subject source, SSP status, and subject source by SSP status within each level of velocity) revealed a significant Subject Source × SSP Status interaction at a target velocity of 18.7°/s, F(1,131)=6.49, p=.01. A lower order effect of subject source (i.e., family status) was also observed, F(1,131)=11.74, p<.005. Post hoc analyses of the interaction showed that the SSP relatives exhibited significantly lower residual predictive pursuit gain compared with the two community subject groups (see and ); performance in the non-SSP relatives was not statistically different from any of the other three groups.
Smooth pursuit gain during initiation and during the mask. CN: community normals, CS: community subjects with spectrum personality symptoms, FN: normal relatives, and FS: relatives with spectrum personality symptoms.
Measures of Pursuit under Open- and Closed-Loop Conditions
Figure 3 Individual data for residual predictive pursuit gain (18.7°/s) in the four groups. CN: community normals, CS: community subjects with spectrum personality symptoms, FN: normal relatives, and FS: relatives with spectrum personality symptoms. Solid (more ...)
The smooth pursuit latencies at initiation were similar in relatives and community subjects (193±34 and 192±29 ms, respectively). Eye acceleration during the first 100 ms of initiation was not statistically different across groups ().
Regression analyses were used to separately model how smooth pursuit is maintained in relatives and community subjects by examining the relationships between eye velocity during pursuit maintenance and its two components: responses to retinal and extraretinal motion signals. The results are summarized in . In both groups, retinal and extraretinal components significantly predicted the eye velocity during pursuit maintenance (p
<.01). Bivariate correlations between the dependent and the two independent variables are shown in . Standardized regression coefficients (Beta values) associated with the two independent variables were significantly different in the two samples. The standardized regression coefficient associated with retinal velocity was significantly smaller in community subjects (β
=0.054) compared with the relatives (β
= −2.46, p
≤.02 (Cohen & Cohen, 1983
). In contrast, the coefficient associated with extraretinal velocity was significantly greater in the community subjects (β
=0.054) compared with the relatives (β
<.002). Separate regression analyses in subgroups of relatives showed similar findings to those obtained for the entire family cohort: Standardized regression coefficients (SE
) values associated with the initiation eye velocity were .37 (0.07) and .27 (0.13) in the nonSSP and SSP relatives, respectively; and, were .47 (0.07) and .17 (0.12) for eye velocity during the mask.
Regression Analyses in Community Subjects and Relatives. Model: Pursuit Maintenance Eye Velocity=Betar × Retinal Eye Velocity + Betaer × Extraretinal Eye Velocitya
Figure 4 The four scatter graphs illustrate bivariate correlations between eye velocity under closed-loop condition (y-axes) and during initiation (top two graphs) and during the mask (bottom two graphs). The two graphs on the left are from the community subjects (more ...)