208 AM J OPTOM & PHYSIOL OPTiCS Vol. 57, No. 4

Trials, or stimulus presentations, are plot-

ted against fusional convergence demand.

From this figure, it is apparent that when

convergence demand is low, performance is

better. When convergence demand approx-

imates the recovery point, response errors

occur (decreasing slightly subsequent con-

vergence demand). With continued prac-

tice, improved performance reflects an in-

creased ability to fuse the greater conver-

gence demand stimuli. This is represented

by an increase in the slope of the conver-

gence line.

Figs. 2-5 depict the final RDS fusional

convergence demand obtained by each pa-

tient at the end of each training session.

The dashed vertical line separates the ex-

perimental procedure, operant RDS con-

vergence training, from the vectogram per-

formance levels attained during previous

vision training. It is readily seen that all

four patients showed dramatic improve-

ments in RDS convergence ability during

experimental training. Since vectogram

convergence ranges also improved during

RDS training, it can be assumed that the

effects of RDS training transferred to vec-

togram testing. This improvement occurred

in terms of both vectogram convergence

break and recovery points.

Another indication of the effectiveness of

RDS convergence training is represented

by a general change in each patient’s visual

performance during subsequent regular vi-

sion training sessions. For patient JH, vec-

togram break and recovery points did not

always correspond well with verbal report

of size and distance localization.e Following

RDS training, correspondence occurred

regularly. In addition, prior to RDS train-

ing, cover testing indicated a 15 pd intermit-

tent exotropia at distance occurring approx-

imately 50% of the time. After RDS train-

ing, an 8 A exophoria was measured via

cover testing.

Patient PL, an intermittent exotrope who

deviated both at distance and at near,

showed changes similar to patient JH. Be-

fore RDS training, vectogram training

yielded inconsistent findings in which re-

ports of suppression on a good number of

vectogram training trials predominated.

After RDS training, fewer reports of sup-

pression occurred along with obtained con-

vergence ranges greater than 30 A.

The vectogram break and recovery point data

shown in Fig. 2 represent findings only on those trials

in which correspondence occurred with verbal reports

of size changes and distance localization.

FIG. 1. Represents increases and decreases in convergence demand for patient P1 during 105 trials during

session 6 of operant RDS convergence training. Increases in the slope of the convergence line are a function

of correct responses to disparity RDS of increased convergence demand. Plateaus or decreases in the slope

of the convergence line represent correct responses to ROS without disparity or incorrect responses to either

training stimulus. resoectivelv.