Training of efficient oculomotor strategies enhances skill acquisition

Acta

Psychologica

71 (1989)

217-242

217

North-Holland

TRAINING OF EFFICIENT OCULOMOTOR ENHANCES SKILL ACQUISITION Kimron

L. SHAPIRO

and Jane

STRATEGIES

E. RAYMOND

*

University of Calgary, Canada

The

present

acquired

study

through

investigated

practice

the

hypothesis

complex

visuomotor

different

set of simple tasks, or drills. One group,

received

training a second

group

training

designed

to increase

video

designed

with practice

to

training

and matched

training

exhibited the inefficient

significant

minimize

of subjects,

the frequency

to a control

for total

significantly or control

inverse correlation in the acquisition

movements

oculomotor

behaviours

and

Performance

the number

path

behaviours,

group,

training

received was inter-

groups

but receiving

The group receiving

efficient

to a

group,

in the

no specific oculomotor

in the video game and fewer foveations from each other.

of foveations

perceptual

motor

Overall

than

there was a

in the game and game score. The

in terms of their implications

of any complex

scan

be to a

were exposed

experimental

two experimental

the video game

can

subsequently

experimental Oculomotor

of these

group playing

which did not differ

between

optimize

of eye movements.

performance

groups,

eye movement

eye movement

time in the experiment. superior

results of this study are discussed training

eye

the efficient

the inefficient

on the video game.

game was compared

either

efficient

tasks and can be transferred

task, such as a video game. Each of two groups of subjects

whereas spersed

that

on a series of simple

for the importance

of oculomotor

task.

A video game is a predominantly visual task. As such, the cognitive and motor skills which determine game performance depend on an efficient flow of relevant visual information (Birch and Lefford 1967; Howard 1971; Williams 1974). Since eye movements act to place specific images on the fovea for detailed visual analysis, the perceptual, cognitive

and visuomotor

systems

critical

for game

play cannot

per-

form optimally unless the oculomotor system is operating at maximum efficiency. Eye movement control is particularly important when the * The authors the resources assistance draft

wish to thank necessary

Donchin

the present

in the initial stages of the project,

of the manuscript.

laboratory

We would

at the University

Requests Calgary,

Dr. Emanuel

to accomplish

2500

for reprints University

OOOI-6918/89/$3.50

should

Elsevier

Dr. Barry

and Dr. N. Moray like to thank to K.L.

Calgary,

Science

Shapiro,

Alberta,

T2N

Publishers

for helpful

in collecting Dept. lN4,

of Illinois

Dworkin

the personnel

for their assistance

be sent

Dr. N.W.,

0 1989,

also

of Calgary

and the University work,

for providing

for his advice

comments

and

on an earlier

of the Vision/Cognition and analyzing

of Psychology,

Canada.

B.V. (North-Holland)

the data.

University

of

218

K. L. Shaprro.

J. E. Rqwond

/ Trarnrng

oculomo~or

strategies

visual scene is dynamic in nature (e.g., Senders 1983) as is the case in a video game. The present study investigated the role of oculomotor control on the acquisition of video game skills. The experiment was designed to: (1) determine whether specific patterns of oculomotor behaviour could be trained, and (2) assess the influence of specific eye movement strategies during acquisition of skill in the project-wide video game, Space Fortress. (For a complete description of the game, rules, stimuli, and required responses, see Mane and Donchin 1989, this vol.) Since the visual, cognitive and motor tasks required in a video game are simplified versions of tasks found in a variety of sport, vehicle guidance, and other situations, the results of this study have implications for training skill acquisition in more complex environments. Two classes of eye movements are critically important for playing most video games and similar perceptual tasks. Saccadic eye movements, characterized by abrupt, rapid and ballistic eye movements, act to detect and correct for differences between target location and eye position, thus producing foveation of a target. The saccadic system is used both when searching a static visual display and when initiating foveation of moving objects. The second class of eye movements are smooth, slow movements which are typically stimulated by relatively slowly moving objects with smooth trajectories. These eye movements, known as smooth pursuit eye movements, are used to match eye velocity to target velocity for the purpose of tracking a moving object, i.e., maintaining foveation after an initial saccade to the object. Foveation during object movement permits the acquisition of important information about object velocity and shape. When viewing a dynamic display, the two eye movement systems are used sequentially to produce a scanpath. A scanpath can be defined as a series of saccadic eye movements alternated with short fixations (of stationary objects) or foveations (of smoothly moving objects) which allows the viewer to sample the visual environment discretely. Cognitive control over the scanpath permits an observer to choose various strategies for assessing the information in a display. For example, when the observer knows where to find important information, increasing the number and rate of saccades when viewing a stationary scene increases the opportunities for data sampling and thus increases the probability of appropriate selection of input information (Festinger 1971). In dynamic viewing situations, however, where objects may appear and disappear unexpectedly, it can be argued that there are disad-

K. L. Shapiro, J. E. Raymond

vantages to frequent sampling. area may decrease detectability

/ Training oculomo~or stra&gies

A saccade to an inappropriate of objects appearing at another

219

viewing location

of the display. Since saccadic eye movements are extremely fast, visual detection is reduced during the eye movement (Matin 1974). The more frequently saccades are made, the greater the proportion of time spent with a functionally blind visual system. Furthermore, the initiation and execution of a saccade may cause a drain on attentional or cognitive resources. Thus, efficient use of the oculomotor system should enhance performance in dynamic tasks requiring fast responses by controlling and limiting the flow of visual and cognitive information. Learning to perform a task optimally may therefore involve the acquisition of efficient, as opposed to inefficient eye movement or scanpath, strategies. Indeed, research on scan path patterns adopted in cockpit situations has shown that observers spontaneously develop efficient patterns of eye movements in complex tasks (Fitts et al. 1950; Clement et al. 1968; Senders et al. 1964). Senders (1983) has shown that observers learn to respond to the statistical structure of dynamic displays in a truly optimal manner. In the present paper, we investigated whether this process can be facilited with appropriately designed training regimes. Although placing the image of an object on the fovea for detailed processing is the primary function of the oculomotor system, images landing on peripheral areas of the visual field also undergo substantial visual processing. A number of investigators (e.g., Eriksen and Hoffman 1972; Posner 1980) have demonstrated that under specific conditions, a subject can dissociate the focus of attention and the point of fixation. Thus when an object appears in the periphery, a subject may utilize the albeit reduced visual processing capacities of the peripheral fields by directing attention to that area and eliminating the costly effort of making an eye movement to fixate the object (e.g., Senders et al. 1964; Moray 1984). If the object is large enough to be effectively analyzed by the peripheral areas of the visual field, then shifting or widening attention to peripheral areas may be an important contributor to an efficient oculomotor strategy, assuming that attentional shifts are less costly and faster than oculomotor shifts. Efficiency of visual search in a continually changing display may involve: (1) eliminating repetitive saccades to stimuli which had been previously analyzed (assuming memory for what had been previously viewed is perfect), (2) eliminating saccades to stimuli known to be

220

K. L. Shapiro. J. E. Raymond

/ Trmning oculomofor

.stmtegies

invariant and previously found to be irrelevant, (3) eliminating eye movements used to foveate images which can be analyzed sufficiently with the peripheral visual field, (4) eliminating reflexive tracking of irrelevant moving of the task.

objects,

and (5) matching

attention

to the demands

Two of the main goals of the present study were to: (I) identify the oculomotor strategies used by naive subjects as they acquired skill in and (2) document differences in the video game, Space Fortress, asymptotic eye movement behaviours between poor and skilled players. Based on pilot studies and other reports described below, we hypothesized that performance on the game would be improved if subjects exhibited an efficiency of eye movements as described previously. The design of the present experiment was to train one group of subjects to adopt an efficient strategy, train a second group to adopt an inefficient strategy, and then compare their performance in the video game with a temporally equated control group receiving no specific eye movement training. There have been several studies relating oculomotor efficiency with skilled performance in static viewing situations. Yarbus (1967) demonstrated that, when asked specific questions about certain objects in a picture, subjects concentrated their fixations on those objects and failed to saccade to irrelevant objects. This finding demonstrates that scan patterns are not random and that subjects exhibit cognitive control over them. Other researchers have demonstrated that when repeatedly asked to view the same picture, subjects adopt specific patterns of fixations suggesting a learning component in the acquisition of scanning strategies (Yarbus 1967; Jeannerod et al. 1968; Norton and Stark 1971). Considerable research on scan path behaviours in airplane cockpits has also shown that subjects develop specific eye movement patterns which reflect the meaning of symbols in the display as well as their statistical properties (Fitts et al. 1950; Clement et al. 1968; Senders et al. 1964). Kundel and Nadine (1978) also applied these ideas to skilled performance by examining differences in the scan paths of novice and expert radiologists viewing lung X-rays. They noted that experts make shorter fixations than novice radiologists. Similar results were reported by Schoonard et al. (1973) who investigated scan patterns of factory workers inspecting integrated circuit chips. Schoonard et al. (1973) reported that, in this specific task, accurate inspectors made fewer

K. L. Shapiro, J. E. Raymond

/ Training or&motor

saccades and shorter fixations. Data that scan path behaviour is learned.

strategtes

from all of these studies

221

suggest

Smooth pursuit eye movements also may be improved with practice. Bahill and LaRitz (1984) reported that expert baseball batters had faster smooth pursuit eye movements and better control over the head and eye coordination necessary for gaze stability than amateur batters. Moreover, Ludvigh and Miller (1954, 1958) reported that dynamic visual acuity, a task largely dependent on the ability to smoothly track a high speed target, improves with practice. The above studies suggest that practice can modify eye movements in a manner that is correlated with improved performance on a task and that oculomotor behaviours for a given task may be habitual in nature. However, in these studies changes in the eye movement behaviours have occurred through repeated exposure to the same task on which performance subsequently is measured. Thus it is not clear whether the oculomotor habits acquired through practice are simple by-products of learning other skills necessary to task performance, or whether acquisition of appropriate scan path behaviour is a more active process such as acquiring a specific manual skill. If the latter is the case, then scan path and general oculomotor behaviour may be generalizable from one task to another. The present study sought to examine in a direct fashion the role of learned oculomotor strategies on performance. If appropriate eye movement behaviour patterns, or habits, actually lead to better performance, then acquiring ‘good’ scan path habits in one task should improve performance on a second task, provided that the optimal eye movement strategy is similar for both tasks. Such an argument supposes that eye movement strategies are habitual and generalizable in nature and that training oculomotor behaviours may be an important aspect of training regimes for complex visual motor tasks. If, however, the acquisition of oculomotor habits are specific to a task and are not generalizable, then practice on one task should have limited effect on performance on a second task even if the optimal eye movement strategy is similar for both tasks. In the present study we devised two practice regimes, i.e., two sets of simple tasks (drills), which were designed to produce two different eye movement strategies: frequent or infrequent changes in foveation. Exposure to these drills is analogous to practicing piano scales in an effort to acquire the complex skills critical to playing an entire piece of

222

K. L. Shapm,

J. E. Raymond

/ Trarnmg oculomotor strategm

music. In other words, unless accurate control over finger movement is initially acquired, the cognitive skills required to read and interpret the written music cannot be manifest in performance. In the present context, practice on the ‘inefficient’ or ‘efficient’ drills should produce the adoption of corresponding inefficient of efficient oculomotor habits. If oculomotor habits are generalizable from one task to another and eye movement behaviour plays an important role in performance, then practice on the inefficient versus efficient drills should lead to decremental or incremental differences in performance on the video game, respectively.

Method Subjects A total SD = 1.3) subject

of 33 male undergraduates were paid

selection

or uncorrected the experiment

procedure according

(described

scores

during

ranging

in age from

of the study.

appears

visual acuity

were no significant task

participants

elsewhere

differences

chapter)

description

All subjects

The distribution

skill level of subjects

in score between

in a previous

17 to 22 years (M = 18.9;

complete

in this volume.

of at least 20/30.

to entry

A more

to the various

is described

groups

groups

in table

on the project-wide

or on the mean

of each

of the

had corrected

subject’s

of

1. There screening

five lowest

game play.

Appuratus The video game, Space and Donchin

Table

(1989,

Fortress,

this volume).

was played using the equipment Eye movements

were recorded

described

in Mane

using an Eye Trac 210

1

Assignment

of experimental

and control

Controls

(N)

groups by entry Efficient

level Inefficient

group

reg.

e.m.

e.m. [l. 121

e.m.

cm.

(2)

(6)

(9)

(7)

(9)

group

Mean entry screen

score

1,020

1,007

1,040

- 936

- 1,565

- 934

2,981

2,547

3.461

1,087

1,017

Mean low a game score

-1,125

- 1,098

Mean high a game score

a Low or high game score

is defined

as the average

3,412 of a SubJect’s

personal

2,591 worst or best scores.

K. L. Shapiro, J. E. Raymond infrared

eye movement

used to support

monitoring

the subject’s

device

recording

apparatus

surement

was also

recorded

fixation

were superimposed

and white

video camera)

video

tapes

which

appeared

different speed

About

tape.

Signals

(filmed

Calibration

prior

indicating

played.

white

crosshairs

eye movement one

quarter

of the

half

of the tapes

and about

group were scored by observers and also naive to the purpose

on a video

records

using

records

mea-

the location

of

with a Sony HVC 2800 black

who categorized

by observers

of the

to oculomotor

were viewed

scored

observers

on video

223

tape. A chin rest was

recordings.

of the game or drill being

as a moving

playback.

different

on video

was made immediately

on a video recording

subsequently

observers

and stored

head during eye movement

eye movement and

/ Traming oculomotor strategm

The

resulting

picture

video

were

of the game.

tape players

scored

randomly

from

Inter-observer

the game followed

the project-wide

twice

each

who were blind as to the group assignment

Five

with slow

at least

chosen

of the experiment.

composite

eye movements

by

subject

of a subject

reliability

was very high

(r = 0.96). Procedure All subjects outlined Illinois

control

had their groups eye

when playing

in a previous

movement day

movement

inefficient

according

all efficient

reading

instructions This

and inefficient

instructional subjects

on the third session with two blocks

had

their

appearing

All remaining

efficient

eye

routine

subjects

in table

Three

experimentals

movements

recorded

2. A fourth

and every

group

recorded

as

of the

of the experiment.

the game during

played

(eye

on the first

time eye movements

control

etc. Within

after viewing practice

Each

by a block

video

except with

of these session

again were recorded

followed

respect

group were performed

approximately

in time (in the experiment)

began

on each drill

consisted

of eight

for all subjects. [1,12] group.

the

of

to viewing on blocks

schedule

the

the instructional oculomotor

Eye

4, 6, 8, and

eye movement

the limits of practicality,

control

chapter),

was introduced

one block of each drill plus one block of

the efficient

group

tape

the rest of the

of practice session

of

for two

of all subjects

during a single block of the game on session

eye movement

groups.

instructional recordings

Drill

until the ninth session.

twelve comprised

identically

eye movement

session,

consisted

below)

the first quiz (see an earlier

of the game.

game play, followed

subjects,

movement

the quizzes,

In the second

of game play. The tenth and eleventh

9 in all experimental

in detail

the first project-wide

six blocks

and continued

which

groups

the first session

of game play. Eye movement

session.

also were recorded

eye

groups,

each drill (described

video tapes and writing

of game play. Session

movements

mental

group.

eye movement

experimental

by viewing

block

of (canonical)

and then four blocks

writing

control

two sessions

procedure

the exact

had their eye movements

for and practicing

was followed

all experimental

inefficient

schedule

experimentals)

were made during this initial project-wide

The

controls,

experimentals)

to the

and then one five minute

blocks

the regular on a least

standard

followed

day only.

For minutes.

recorded

(eye movement

(1,121 efficient

and twelfth

Two of the subjects

group and are termed

eye movements

of subjects

second

chapter.

efficient video

recordings

and tapes, of the

of game play that corresponded

to eye movement

recordings

for the experi-

group

Blocks played Cum. blocks Cum. minutes E.m. record time Drills

Ineffwient group

Blocks played Cum. blocks Cum. minutes E.m. record time Drills

Ef/iicient

Blocks played Cum. blocks Cum. minutes E.m. record time

Control group

1 1 26 26 I/

1 1 26 26 r/

5 5 40 20

1

Table 2 An outline of the procedure

7 8 61

7 8 61

7 12 75

2

for all groups

r/

4 12 87

I/

4 12 87

6 18 105 105

3

4 16 114 91 v

4 16 114 97 I/

8 26 145

4

r/

6 22 145

r/

6 22 145

6 32 175 175

5

6 28 166 155 I/

6 28 166 155 r/

8 40 215

6

6

r/

6 34 222

r/

6 34 222

46 245 245

7

6 40 258 232 I/

6 40 258 232 r/

8 54 2X5

8

6 46 294 294 r/

6 46 294 294 v

6 60 315 315

9

8 54 334

8 54 334

8 68 355

10

8 62 314

8 62 374

8 16 395 395

11

1 63 385 385 1/

1 63 385 385 I/

12

K. L. Shapiro, J. E. Raymond / Trainuzg oculomotor strategies All

experimental

project-wide

A block

of practice

to the subject

instructions

drill

group,

1 was designed

to discourage

objects

in the display.

moving

object

and direction

For both varied

as quickly

of the next

form of feedback just

object

beside

1.6 degrees

studies

On

suggested

subject

interval

over the appeared.

of the fire button

and then started

a

the speed

had no control

of the stimulus.

half of the trials

After

in an

a button

to move again

to the subject

the stimulus

trials,

Subjects

to the ship and to attempt to detect

between

contained

at

in the

of trials.

in the periphery.

that novices

appearing

saccades

the screen

and displayed

the remaining

of visual

to peripherally

(see a description

The dot was small enough

was necessary

(approximately

for a brief

appearing

The

RT was recorded

the ship.

unnecessary

For the inefficient

on each trial, although

after detection

on a random

fovea1 vision

vision.

foveation

Pilot

group,

(mine)

their

peripheral

trials.

were

Subjects

after the start of each trial, a stimulus

as possible trial.

Drills

and buttons.

and to promote

at the start of a trial,

between

at the end of a block

For the efficient

in the

each drill.

eye movements attention

at a fixed velocity

interval

the ship was immobilized

appearing

groups,

feedback.

the joystick

for use in ship control.

task was to press the fire button

the beginning

to direct

by the

Feedback

of drill 1 was to eliminate

attention

to encourage

At a random

chapter)

performance

including

the use of peripheral

of motion

The subject’s

to provide

the purpose

(ship) which drifted

ship’s movement.

moving

as required

in duration.

to read prior to playing

and train peripheral

objects,

press,

60 minutes

was two minutes

game equipment,

For the efficient

eye movements

previous

than

for drills 1 and 2 or a game score for drill 3 was displayed

at the end of each block

were given written

that

for each drill

time (RT)

using the regular

group,

no longer

drills

form of a reaction

Drill I:

lasted

standard.

Visuomotor

played

sessions

225

angle)

to detect

while

to detect

probably

was

a larger

in this group were instructed

(approximately

its presence

was a small dot

the stimulus

the mine with their

3 minutes the mine

its presence

need to fixate

of visual angle)

was large without

enough

foveation.

the ship in order

to learn

ship control. For the inefficient itself

group,

or in the other

appearance

of a small

order to detect second

small

appearance. button between

half,

dot

appeared

the mine

beside beside

mine and ship. Subjects

dot beside

required

it. The

subjects

the ship

at a random

on these trials the ship.

Thus

were instructed

was a mine by

possibility

to foveate

On trials in which a dot appeared

were instructed

a dot appeared

half of the trials the stimulus

with a small

dot beside

the dot’s presence.

Subjects

until

on a random a mine

beside

interval

to withold

of the

the mine

after

responding

they were encouraged

to keep their eyes searching

in

the mine, a the mine’s on the fire to saccade for mines

at all times. DriN 2:

For the efficient

saccades

to peripherally

group,

the purpose

appearing

objects,

of Drill

2 was to train subjects

to use peripheral

attention

to inhibit

when possible,

226

K. L. Shapiro, J. E. Raymond

and

to improve

location.

For

peripherally

eye

movement

the inefficient appearing

peripheral

elements

present.

button

on the screen

but rather

the subject

had to respond

required

responses

to be made

and displayed

that in addition

as possible

to the subject

a friend),

for a friend

a mine was also

and to press

half of the trials,

the ship, as in drill 1. When

the fire button

as quickly

to

for detecting

whether

the fire button

beside

by pressing

a fixed

saccades

to drill 1, except

for a foe. On a random

a dot appeared

with

used to indicate

a foe and a ‘3’ indicated

to press

button)

to objects to encourage

to use fovea1 attention

a small letter,

indicated

was required

(the IFF

not appear were

saccading

and to train subjects

or a foe (an ‘E’

The subject

different

when

drill 2 was to designed

of the game. This drill was similar

to the ship being present was a friend

accuracy

group,

objects

/ Trurning oculomotor stmtegirs

this occurred

as in drill 1. All trigger

and

an RT

in the form of feedback

a

a mine did presses

was recorded

for all

at the end of a block

of

trials. For

the efficient

screen. This

The letter

changing

group,

letter

the periphery.

provided

visual display (e.g.,

from

the letter

foveation

the fortress was small

to foveate

not present

unless

ship, however, needed

landmark DriN 3: ship

(without

(requiring

drill,

tracking

to execute

eye

movement

ship

drill 3 was designed the drill was designed were in control

was established began a mine

of motion before

drill

Drill

during

to encourage of the ship’s

response 1 and 2

the ship appeared

of a dot appearing a minimal

RT.

that good players phase

foveation saccades

beside

the

ship and mine No

stationary

tend to foveate to train

of learning.

For

the

efficient

or

the efficient

of the ship while, for the inefficient between

orientation to apply

and remained and

between

the was

drill.

ship and mine.

in space thrust).

The direction

constant

immediately

In drill 3,

but had no control

on the sceen. At a fixed interval location

or foe. The letter

3 was designed

this

(i.e., they are unable

in a random

task with

suggested

to encourage

when the ship appeared appeared

its

then the letter

a motor

of the mine requiring

it was friend

The possibility

control.

patterns

group,

the direction

that

Rather,

near the ship in drills

in the center

whether

in this particular

pilot studies

learning

group,

all subjects

angle)

all the time,

an eye movement), before

in

to the fortress.

of visual

it was present

of the ship so that saccades

the inefficient for subjects

As stated earlier,

inefficient

appeared

to determine

the mine was present.

encouraged

while

and then back

of the letter)

at the

are triangular

of a mine in the periphery.

eliciting

This

eye movement

that experts

often

in

in the

a map of the display.

0.5 degree

of a dot appearing

the letter

the mine

was provided

steadily

a landmark

of a specific

patterns

Since

foveation

above.

when a mine appeared

we determined

fixation

the presence

of the

as described

of the ship.

For the inefficient subject

studies,

Their

(approximately

be made. The high probability foveation

to developing

discrimination.

first had to be detected

encouraged

were

enough

alone could not have signaled

the mine could

In pilot

in the center

it provided

to the ship, to the mine,

for letter

had to be discriminated

except

was added because

as their landmark.

was needed

presence

information

intervals

the size and direction

the ship to the letter).

going from

continuously

at random

quite critical

in calibrating

game use the fortress Second,

letter

which is probably

may be useful

was displayed

but changed irrelevant

The stationary

map

nature

the letter

was stationary

through

over

of motion

a trial. A trial

after the ship appeared,

began

to track

the

ship.

K. L. Shapiro, J. E. Raymond / Training or&motor Subjects

in the efficient

quickly

as possible

group were instructed

by correctly

orienting

they were instructed

Additionally,

ship thus encouraging

to attempt the ship

to score a hit on the mine as

and

depressing

to shoot at the mine without

them both to detect

22-l

strategies

the

fire button.

taking their eyes off the

and shoot at the mine using their peripheral

vision. For the inefficient appearance

group,

a small dot appeared

the dot appeared

to begin hitting

was encouraged

to promote

rapid

a score which reflected Eye movement

into

periods. absent block

record

separately

the subject’s

analyzed

their proficiency

goal

A no-mine

of eye movements in each

a series

was defined

during

was different.

reduced

in the form of

which

as a block

a mine was present

and was terminated

period

both drill and game play mine present

Thus

distinguished

each

vs. absent,

game

between

mine

of time during

which

goal was to fire at the fortress.

A no-mine

block

and

the mine was

A mine period was defined

and the subject’s

was

no-mine as a

task was to hit the

began when a mine disappeared

from the screen

when the next mine appeared.

of foveations

The

primary

objects

function

in a visual

perspective,

of eye movements

display

it is of interest

time

period,

movement

movement

recording

measure

3 foveations also recorded

fovea.

how many

respectively.

with a fixation

because

mine and no-mine

processing

were foveated

or a smooth

in a

pursuit

eye

extracted

of foveations

of different

objects

made

For example,

if a subject

began

an eye

on

was the mean number

of the many

one of the measures

of the fortress,

object

image

information

objects

fixation

and then saccaded the

which an

different

Therefore

was the number

periods,

From

a steady

the foveation.

the ship for a short period

constitute

is to control

the

of whether

records

period

on

to know

was used to achieve

mine and no-mine

tracked

lands

regardless

from the eye movement

during

prematurely

drill.

game situations:

which

for whatever

reason

obtained

situation

of periods

period

of time during

during

Firing

to wait until

the ship and mine

in drill 3 was provided

with this particular

mine with a missile.

given

between

of the dot.

for the two distinct

and the subject’s

Number

after the mine’s

measures

The continuous was analyzed

detection

for all subjects

interval

were instructed

the mine. Thus saccading

their score on the drill. Feedback

since

at a random

either near the ship or near the mine. Subjects

the

back fovea

then saccaded

to the ship,

to the fortress, changed

this would

twice.

of times each game object

A related

was foveated

periods.

Previous object viewed A second the subject (no-mine

measure

periods)

percentage

made

from the eye movement

immediately

or a mine

viewed a given object the subject

extracted

was viewing

(mine

prior

periods).

prior to a successful

a successful

of times the subject

hit for each

records

to making The

concerned

a successful

total

number

which object

hit on the fortress of times

the subject

hit was divided by the total number type. This

viewed a particular

ratio

object

served

of times

as an index

while making

of the

a successful

hit.

228

K.L. Shapiro, J. E. Raymond

Proportion

strategies

of foveations

A third foveations

measure directed

dividing

/ Truimng oculomotor

calculated

from

to a particular

the number

of times

the eye movement

object

during

a particular

records

each period

object

was the proportion

of

type. This was derived

was viewed

by the total

by

number

of

foveations.

Results Game score analysis Since

performance

on the Space

game score, comparison will be discussed game scores

defined

value

subject, significant

differences

control

groups

groups.)

The

sures variable action groups

effect

were reached

(F(2,

tended

For this reason,

to the mean

measures

revealed

(F(1,

lowest

scores

described

data

from

the

hoc

tests

two

for each subject. for each

there

were

no

data from the two

efficient

effect,

among

recorded

a group,

previously,

groups

Post

scores

scores

by

on the game was

achieved

within

30) = 1038.67,

p -C 0.05).

represented

on this measure

to show high variability

(Since,

a non-significant

significance in their

ANOVA. as were

best

peak performance

of the five lowest

the sub-groups

combined

30) = 3.62,

did not differ

is probably

as the mean of the five highest

between

analysis

game

in each of the three groups

in all groups

blocks.

was compared

in a repeated

Fortress

all subjects

Subjects

on successive

operationally This

first.

among

experimental

but the repeated

mea-

p < O.Ol), as well as the interrevealed

on the game

(see

that while table

l),

the three

the efficient

4000 3000

efficient

inefficient

control

Group Fig. 1. The mean low and high game score for each group. as the average

of each indicated

subject’s

five personal

worst

Low and high game score are defined

or best scores.

respectively.

by the solid black bars and high score by the striped bars.

Low

score

is

229

K. L. Shapiro, J. E. Raymond / Training oculomotor strategws

. efficient 0 inefficient 0 Calgary control n Illinois control -2000

t

,

.

60

.

in experiment

(

,

300

240

180

120

time

.

360

(minutes)

Fig. 2. Group mean game score obtained on the last block of each session plotted as a function of time in the experiment (including drill practice).

experimental higher

group had a mean highest

than that of the control

the inefficient

experimental

score (mean = 3439)

group (mean = 2655;

group

(mean = 2590;

highest

score of the inefficient

experimental

control

group.

these data.

Fig. 1 illustrates

Performance

in the project-wide

t(13)

group

game,

t(22)

Space

approximately

= 2.23,

spent

sessions

in which

second both

eye movements

efficient

groups

control

minutes

into

i.e., playing

were recorded

represents

improved

the game

group.

and statistically

Using

control

the groups

consistently

probe

non-significant

drills.

the score

the same rate and marginally

At this point,

highly variable

as a function

or practicing

For

on the

As can be seen in this figure, performance

at about

group demonstrating

experimental

a single,

that of the

in fig. 2 which

plotted

on the last block,

group but at the same rate as the Illinois the experiment.

experimental

and inefficient smaller

of the screen,

last block was used in the analysis.

experimental

the Calgary 250

in front

from

is illustrated

shows the group mean game score of the last block of each session of time

The average

p < 0.05).

was not different

Fortress,

800 points

p -C 0.05) and that of

= 1.96,

only

the last block

difference

between

to differ

scores

with

session

of the subjects groups

the

than the control

of each

into the performance

of than

group until about

begin

higher

faster

which shows a

at the end of the

experiment. Eye movement

analysis

The mean number as a function 3. Total groups

of foveations

per no-mine

of time in the experiment

time in the experiment at each recording a significant

effect

= 5.10,

p -C 0.01)

no-mine

data over all sessions

and

was roughly

session

revealed

no

(see table

of group (F(2, significant showed

and mine periods

of the game plotted

is shown in panels A and B, respectively, equivalent

for experimental

2). An ANOVA 18) = 8.47,

interaction no significant

on the mine period

p < 0.01)

effect. effect

of fig.

and control

A

and session

similar

of groups

analysis

(F(4, of

data 72) the

but a significant

230

K. L.

A

efficient

A

n inefficient

0

control

<

m

20

100

165

approximate

245

time

A

20

165

100

approximate

300

in experiment efficient

245

time

390

(minutes)

390

300

in experiment

(minutes)

Fig. 3. The group mean number of foveations during the game plotted as a function of eye movement recording session for the no-mine periods of the game (panel A) and the mine periods of a game (panel

B). Total

time in the experiment

control

session

effect

(F(4,

ever, repeating effect

effect.

For both

experimental inefficient

72) = 3.56,

the analysis

groups

(F(2, group

had

significantly.

and inefficient

no significant

periods,

foveations

post

groups

had means

hoc tests

(p < 0.05)

By the last block per mine period

for experimental

interaction

from the last three sessions

group and that the control

a mean of 2.23 foveations control

fewer

and

equivalent

and

session (see table 2).

p < 0.05) with a non-significant

and no-mine

experimental

did not differ

p < 0.01)

on data

18) = 4.59, mine

was roughly

groups at each recording

than

sessions revealed

of the experiment,

and interaction group

experimental the efficient

per no-mine

of 3.16 and 3.54 foveations,

How-

a significant

that the efficient

the control

and inefficient

and 2.28 foveations

effect.

revealed

or the groups

group had period.

The

respectively.

for

K. L. Shapiro, J. E. Raymond / Training oculomotor strategies Table 3 Mean number

of foveations

in the drills.

Efficient group Inefficient group

the mine

periods

possible

experimental

groups

movement number

The number

highly

correlated

The

1.38 3.92

and 3.64

For

all three

over time, although

of foveations = 0.42,

period,

in the initial

groups,

there

this effect

experimental

prior

was

in each

of foveations

periods

of the drills

found

impact

for the efficient

and inefficient

the group mean for each drill showed than the inefficient

p < 0.001).

between

in the game (last session)

was significantly

and drill 3 (r(14)

p < 0.001)

= 0.70,

to minimize

obtain

relevant

category,

saccades

the mean

for each subject.

effect

18) = 3.86,

(F(2,

0.01)

foveations

and inefficient

experiment,

the efficient

0.97,

while

in the efficient

or stimuli

the mine

group

the inefficient

a stimulus

was foveated

effect.

effect

the control

(F(4,

or the inefficient

had a mean of 0.59 and control

period

was group

72) = 8.64, group

group

p -e

had fewer

( p < 0.05)

By the last block

foveations

groups

to

of the latter

a significant

the efficient

significantly.

foveation

in a mine

of session

As before,

did not differ

group

p < 0.01)

experimental

not requiring

on these data revealed

a significant

interaction group

of foveations

= 0.70,

and

of the

of the mine per mine

had mean

values

of 0.96

and

of times

the

respectively.

Related subject Fig.

stimuli

An ANOVA

of the mine than either

the control period,

of times

p < 0.05)

and a non-significant

for drill 1 (r(14)

Since the mine may be considered

number

determined

made

and drill 3

in drill 2 was non-signifi-

and the number

was to train subjects

to irrelevant

information.

group

p < 0.001)

but not for drill 2.

One of the goals of the experiment group

the groups

correlated

experimental

is shown in table 3.

= 9.65,

in the drills (last session)

to

behaviour.

that the efficient

group on drill 1 (t(8)

The difference

of foveations

in an effort

on oculomotor

comparing

= 8.77,

in

(although

of the game were

was also analyzed

the desired

T-tests

cant. The number

decline

and less so for the inefficient

for each of the three drills on the last day of the experiment

(t(8)

to the first eye

was more pronounced

group

A

is that the

a general

groups

fewer foveations

respectively.

sessions

p < 0.05).

of foveations

number

groups

in the mine and no-mine

if the drills did in fact produce

mean

per no-mine

to their drills immediately

exposure

session.

(r(29)

number

foveations

received

so) for the efficient

group. The

Drill 3

1.63 1.99

among

of gaze changes

determine

Drill 2

for the difference

recording

not statistically

Drill 1 0.92 3.24

3.12

and

explanation

231

to this

foveated

4 illustrates

function

finding

was a significant

the number

of foveations

of time in the experiment.

group

effect

8.50,

p < 0.01)

inefficient

difference

the region of the letter (indicating

(F(2,

18) = 4.91,

group

had significantly

to the letter

An ANOVA

p < 0.02)

and a non-significant

the mine was friend or foe). region

on the data

a significant

interaction more

in the number

whether

effect.

foveations

effect

per mine revealed of

session

period (F(4,

Post hoc tests showed

than

the efficient

as a

a significant

group

72) = that the

(t(77)

=

232

K. L. Shaprro. J. E. Rqwnond

/ Training oculomotor strategies

100

20

165

approximate Fig. 4. Group

mean number

or foe plotted efficient

of foveations

as a function

group

of time

are represented

time

245

300

in experiment

390

(minutes)

in the region of the letter identifying

in the experiment

by the closed

(including

triangles,

the mine as friend

drill practice).

Data

for the

group by the closed

for the inefficient

squares and for the control group by the open squares.

4.52,

Differences

p < 0.01).

between

By the end of the experiment, as many times

foveations

the subject

as the efficient

foveated

may also be considered digit

is only

approaches checking

relevant ten,

revealed

tests revealed ferences control

the

groups

analyses

to these objects foveated these

divided

groups bonus

the digit

and the information foveations For

periods

would

in this

Repeated

contribute

An ANOVA

effect

effect.

Post

half as many foveations = 1.98,

(mean = 0.26)

to

on these data

a significant

interaction t(14)

of hits

has accumulated

is required.

logged

p < 0.05)

groups

the control objects

to other

objects)

of total

subject

of hoc

of the

p < 0.05).

and

between

Since

effect

there

for all subjects (panel

than (i.e.,

the efficient the number

showed

Difthe

initially

Therefore,

the

an object

was

A comparison difference game

fortress

differences,

and are presented

it is

foveations

group.

for certain

were no group

A), subjects

more

was examined.

of cumulative

groups

However,

of times

no significant

of session

the number

experimental group.

make proportionally

foveations)

groups

(p < 0.001)

and inefficient than the efficient

groups

was foveated

displaying

box).

were averaged

the no-mine

that

and inefficient

an object

and a significant display,

memory.

fortress

The information

the subject

(mean = 0.33;

control

of accumulated

response

18) = 500,

group

to particular

the three

motor

one and a half the number

were non-significant.

by the number

for

hits

and a non-significant

and

shows

(as opposed

of times

values

(F(2.

were non-significant.

situation,

efficiency.

of fortress

group had approximately

efficient

that the control

proportion

effect

p < 0.05)

make more eye movements not clear

the number

it may improve

as the inefficient

and inefficient previous

In the no-mine

a different

although group

groups

had approximately

only a few hits have been

that the efficient

between

The

point

when

72) = 2.75,

digit (mean = 0.16)

group.

the number

at which

inefficiency,

(F(4,

group

as an index of eye movement

a significant

session

and efficient

the digit displaying

when

of the number

oculomotor

control

the inefficient

in panels

viewed either

elements hits,

of

between (i.e.,

the letter,

the proportion

of

A and B of fig. 5. the fortress

or ship

K. L. Shapiro, J. E. Raymond

233

/ Training oculomoior strategies

no-mine periods

End

Beginning

B

mine periods

8% 28

38X 15% 43x

beginning

end

Fig. 5. Mean percentage of foveations directed to objects displayed on the screen for all subjects in the experiment. Panel A shows the distribution of foveations for the no-mine periods of the game at the beginning and end of the experiment. The distribution for the mine periods of the game at the beginning and end of the experiment are shown in panel B.

on 89 percent displaying

of foveations

cumulative

the experiment,

the percent

more than doubled

with only four and one percent

fortress

hits and the bonus

of foveations

directed

(9% and 5%, respectively)

indicator,

directed respectively.

toward

toward the digit and bonus

at only a modest

the digit

By the end of indicator

cost to foveations

of the

ship and fortress. foveations (4%).

In the mine periods

toward

the letter

(8%).

By the end of the experiment,

objects

had at least doubled

9%). The only object 2.99;

p < 0.07)

block

was the letter

of the experiment, of their

foveations

(s.d.

= 0.08)

and

proportion

the

of foveations

with game score (r(20) A related looking

question

during

15%;

a group which

indicator

= 0.06)

control

group

on

a mine

during

= 0.06)

box,

mine periods

viewed of

=

By the last on

it on 12%

occasions.

and significantly

The

correlated

p < 0.01). whether

aspects

there were differences

of the game.

To

no-mine 80

these

(F(2.19)

or foe.

group

(s.d.

toward

significance

the letter

10%

few box

and information

as friend

was positively

relatively

directed

3%;

the inefficient

only

directed

and the information

approached

viewed

while

made to the letter = 0.63,

indicator,

difference group

initially (1%)

of foveations

bonus

designated

the efficient (s.d.

concerns

specific

B), subjects

the proportion

(letter,

for which

20%

(panel

the bonus

answer

in where the groups

this

question

were

the object

of

periods

T

viewing ship

viewing fort

mine

mixed

periods

60 50 40 30 20 10 0

Fig.

6. The

movement periods)

percentage styles

of subjects

described

or mine (mine

data for the inefficient

viewing ship in each

in the text just

periods).

Data

viewing fortress group prior

mixed

using

each

to a successful

for the efficient

group

of

the

three

categories

hit on the fortress

are represented

group by the striped bars and data for the control

of eye (no-mine

by the white bars,

group by the black bars.

K.L.. Shop&, foveation found

immediately

that subjects, tended

60%

prior

mine periods

to adopt

of

foveations

made

periods)

or mine

mediately

prior

(i.e.&p

tion of subjects similar

styles.

situation

three styles of oculomotor group

firing

a missile.

The mean

related

groups

in the choice

The

last

Using (r(29)

The

positively

of

and game

the statistical

obtained game

of of

to view the ship

between

periods.

the other

of choice

periods,

two

immediately

subjects

was not

among

half the subjects viewed

the

in the prior

to

the fortress

primarily

than the mean

foveating

for subjects

the

evenly

and was higher (by 20 hits). but foveating

the ship.

immediately the efficient

than either

analysis

prior

Differences

to a hit may be

group had an average

the inefficient

p < 0.01)

number

of

of the data

on the last session

score

and

or control

foveations

with RT to hit a mine (r(29)

made

recordings

of

groups

= 0.56,

of eye

of game performance.

were made, a significant of foveations

periods

in the

and the number

is the correlation

with measures

the number

and in the no-mine

of hits on the fortress = 0.60,

was

had changed

score

for which eye movement

between

= -0.49,

found. number

aspect

all subjects

chose

homogeneity

primarily

foveated

imboth

p < 0.05).

measures

correlation

between

(71%) in the no-mine

hits for subjects

that on the last session

of eye movements

movement

of object

fort

of the experiment

of foveations

ship and fortress

for subjects

evenly

group

the control

p < 0.01)

70 more hits on the fortress

28) = 4.31,

Correlation

= 3.72,

between that

to the observation

approximately

(r(29)

so, than

pattern half

the made

were fairly evenly distributed

of fortress

(t(15)

their foveations

not significantly

(F(2,

number

was 87 hits higher

viewing

to view the mine predominantly,

- in the no-mine

periods,

(2)

on the first and last session

this relative

a consistent

In the mine

periods.

that, while the distribu-

distributed

chose

where subjects

behaviour

did not adopt

predominantly.

between

group

a hit in the mine periods,

in the no-mine

distributing

were evenly

67% of the inefficient

no-mine

using each of the three categories

periods

in the efficient

in this group

It was the ship

the ship on at least

this distribution

and the fortress

to making

fortress

of subjects

for the mine and no-mine

subjects

control

It was found

at the beginning

by the end of the experiment,

either

of foveations

foveations

of subjects

Although

found

styles

a hit, 60%

(57%) in the mine periods

remaining

prior

of these

each

The majority

predominantly

their

or ship and mine).

styles

the experiment.

to making

among

during

(1) viewing

on at least

a hit, or (3) splitting

Fig. 6 shows the number

eye movement

The

prior

periods)

and fortress

for all groups,

substantially.

(mine

was examined.

to foveate

and the ship or the fortress

immediately

to making

tended

styles:

235

strutegies

or a mine

to fire a missile,

one of three different

(no-mine objects

/ Training x&motor

to a hit on the fortress

when preparing

or the mine during Subjects

J.E. Raymond

mine

p < 0.01).

(r(29)

= -0.39,

periods

also

For the no-mine

of foveations

negative

in the mine

periods

p < 0.05) was

situation,

was correlated

was

correlated the

negatively

p -=c0.001).

Discussion The present study investigated the hypothesis that efficient oculomotor behaviours: (1) are a fundamental requirement for successful per-

236

K.L.

Shapiro.

J.E.

Raymond

/

Trawmg

oculomotor

strategies

formance on a complex visuomotor task, (2) can be learned in a part-task context and, (3) can be transferred to a complex task. In order to examine this hypothesis, we exposed each of two groups of subjects to a different set of simple part-tasks (drills), so that we might train two distinct oculomotor strategies and examine their influence on the canonical video game, Space Fortress. One group, the efficient eye movement group, received training designed to: (1) minimize eye movements by eliminating repetitive saccades to stimuli previously processed and/or previously found to be irrelevant, and (2) encourage the use of peripheral vision thereby eliminating saccades to objects able to be analyzed sufficiently with the peripheral visual field. The other group, the inefficient eye movement group, received training designed to increase the frequency of eye movements and to encourage the foveation of all objects on the screen. While novice players tend to use the second of these two strategies, experienced players tend to use the former. Performance of these two experimental groups in the video game was compared to a control group receiving no specific training but matched for total time in the experiment.

Performance

in the game

Perhaps the most important conclusion to draw from the results of this experiment concerns the influence of the two distinct oculomotor drills on canonical game score. The group receiving oculomotor training for the purpose of promoting efficient eye movement behaviours exhibited a significant 30 percent higher asymptotic game score then either the inefficient or control groups, which did not differ from each other. This implies that the part-task training experienced by the efficient group was effective in modifying behaviour during video game play. To determine if our specific drill regimen caused the improvement noted in the efficient group as opposed to some non-specific benefit accruing from part-task training in general, we compared game score performance between the efficient and inefficient experimental groups. This is an appropriate comparison, since they were treated identically in all respects other than the eye movement strategy imposed by the drills. Specifically, part-task training for both groups included: (1) exposure to the same visual elements of the game, (2) similar cognitive requirements, (3) knowledge of results presented with the same

K. L. Shapiro, J. E. Raymond

237

/ Trainrng oculomotor strategies

frequency, and (4) equivalent practice with identical motor responses. Since the efficient and inefficient groups differed in asymptotic game score, whereas the inefficient and the control groups did not, part-task training on the game as a whole cannot account for the improvement witnessed in the efficient group. Rather, the enhanced performance of the efficient group must be due at least in large part to the specific nature of the eye movement training in the drills with little or no contribution from other aspects of the part-task training. While we expected some decrement in performance of the inefficient group relative to the control group, the lack of a difference between these groups could be due to the possibility that the drills for the inefficient group were not effective or that the inefficient experimental subjects simply did not transfer the trained oculomotor behaviour to the game situation. Support for the latter possibility can be found in the acquisition of eye movement patterns and is discussed in more detail below. An alternative explanation is that the subjects may have matched their visual attention to the statistical structure of the task in the whole game without any conscious decision to do so (Fitts et al. 1950; Senders et al. 1964) and thus overwhelmed the inefficiency training. Two additional points concerning the game score data can be made. First, the control group received as many eye movement recording sessions as the two experimental groups. Since, our local (Calgary) control group did not differ from the Illinois control group, the repeated eye movement recordings probably did not interfere with game skill acquisition. This allows the data from our two experimental groups to be compared to the program-wide control run at the University of Illinois, as well as allows inferences to be drawn concerning our findings

and

those

of

other

investigators

involved

in

the

project.

Second, there is a point to be made concerning the game score acquisition data from both of the experimental groups as well as both our control and the Illinois control groups. Such a comparison indicates that the oculomotor drills were not effective at speeding acquisition of game scores early in the experiment as would be expected, but were more effective in the last third of the experiment. Oculomotor

strategies

An examination of eye movement behaviours in the oculomotor drills themselves revealed that the drills generally were effective in

238

establishing

K. L. Shapiro,

J. E. Raymond

eye movement

/

Trainrng

behaviours

oculomotor

consistent

strategies

with their intent,

i.e.,

the efficient drills produced fewer foveations than the inefficient drills. This was true, however, only for drills 1 and 3 indicating that drill 2 may not have been designed appropriately. A likely explanation for this is that a minimum of two foveations were required ideally to perform drill 2 for both the efficient and inefficient groups. The other two drills required at least one more eye movement of the inefficient group than of the efficient group to perform the task ideally. The pattern of efficient eye movement behaviours which were trained by the oculomotor drills appeared to have transferred to the complex perceptual motor task requirements of the Space Fortress game. Such a conclusion is drawn on the observation that the efficient group had significantly fewer foveations in the game than either the inefficient or control group. That the efficiency of eye movements displayed by the efficient group may have contributed to their better asymptotic game scores is suggested by the negative correlation (which, of course, must be limited and is task specific) between the frequency of eye movements in the game and game score. Moreover, since there was a strong positive correlation between the number of foveations made in these drills and the number of foveations made in the game, it appears that the oculomotor habits generated by drills 1 and 3 were generalized to the game situation. These data are consistent with the Schoonard et al. (1973) report that good vs. poor performance of factory workers inspecting integrated circuits was associated with scanpaths containing fewer, as opposed to more, fixations. It is important to note in the present study, as well as in the Schoonard et al. (1973) study, that optimizing performance by limiting eye movements is task specific. The present data are, however, also consistent with the general notion that eye movement patterns necessary for good performance in a dynamic task reflect task dynamics and semantics. The effect of oculomotor training on the global measure of game score may have been mediated through an impact on the efficiency of specific aspects of the game, such as mean RT to hit a mine and the average number of hits made on the fortress. If initiating and executing an eye movement occupies a visual/cognitive resource, then the time required to react to a novel object (e.g., a mine) should be correlated with oculomotor efficiency. The positive correlation between the number of foveations and RT to hit a mine supports this claim. In the no-mine situation of the game, good performance entails maximizing

K.L. Shapiro, J. E. Raymond

the number

of hits on the fortress

/ Training oculomotor strategies

before

the appearance

239

of the next

mine. Again, an extra eye movement might be expected to drain visual/cognitive resources necessary for the task of hitting the fort. The negative correlation between the number of foveations and the number of hits on the fortress supports the argument that oculomotor efficiency is related to cognitive and visuomotor efficiency. Not only was the goal of the drills to minimize foveations but also to discourage repetitive saccades to objects which had been processed previously. In the mine periods of the game, a single saccade to the letter indicating whether the mine was friend or foe is sufficient ideally. In actuality, by the last two sessions of the experiment, the efficient group made an average of one saccade to the letter. The inefficient group. on the other hand, made approximately 1.5 saccades suggesting an oculomotor inefficiency. This finding could be interpreted simply to reflect the overall group difference in the number of foveations discussed earlier. However, an analysis of the proportion of all foveations that were directed to the letter reveals that the distribution of oculomotor attention to the letter was larger for the efficient group than for the inefficient or control groups. This means that, although the inefficient group made more foveations overall than the efficient group, they spent fewer foveations on the letter relative to other objects than did the efficient group. The finding that the proportion of foveations a subject directed to the letter was correlated positively with game score suggests that the effect of oculomotor efficiency not only is related to a general reduction in the number of foveations, but also to the appropriateness of objects foveated. In the no-mine periods of the game, an efficient use of eye movements would dictate minimizing foveations to the display indicating fortress hits, since this display would need to be viewed only when the number of hits approached the required number. By the end of the experiment, the efficient group viewed the display once on approximately one out of every five no-mine periods, while the inefficient and control groups viewed the display twice as often. Since the efficient group had significantly more hits on the fortress than the inefficient or control groups on the last block of the experiment, such a finding supports the notion that efficiency of eye movements is related to performance. The eye movement patterns of the inefficient group and the control

240

K. L. Shapiro,

J. E. Raymond

/ Traming

oculomotor

strategres

group generally were very similar, at least by the last session of the experiment. It is likely that the inefficient drills either were ineffective at modifying oculomotor behaviour or that the acquired oculomotor habits were not transferred to the complex task of the whole game. Evidence in support of the latter possibility can be seen in both panels of fig. 3. While efficient and inefficient groups began with approximately the same number of foveations per game period, after approximately 100 min in the experiment (after several sessions of drill practice), the inefficient eye movement group exhibited a sharp increase in the total number of foveations while the efficient group did not. This was particularly so for the mine periods of the game where objects appear in the periphery and therefore drill training might be expected to have greater impact than in the no-mine periods. On subsequent eye movement recording sessions, both groups show a decline in the number of foveations, suggesting that the inefficient group abandoned the eye movement strategy imposed by the drills in the latter stages of the experiment. A similar pattern of foveations can be seen in fig. 4 which illustrates the change in foveations to the letter region during mine trials with time in the experiment. Here again, the inefficient group shows an increase in the number of foveations after approximately 100 min the experiment. Relative to the initial level, there was a two-fold increase in the number of eye movements for the inefficient and control groups suggesting that the inefficient drill training did impact oculomotor behaviour early in training. One of the underlying ideas of the present investigation is that subjects develop when confronted

oculomotor patterns which are applied repeatedly with a similar situation. Evidence that such oculomo-

tor habits were formed is found in the analysis of eye movements during subjects’ attempts to hit either the mine or the fortress. We found that most subjects (about 70%) adopted specific styles of viewing either: (1) the ship, or (2) the object of the attack immediately before firing. The remaining 30% did not display a specific habit but alternated their gaze between ship and object just before firing. In general, the subjects that did not develop a fixed habit had the lowest scores in the subject sample suggesting that habit formation is helpful in performance. For many years it has been demonstrated that the training of any complex perceptual motor task benefits significantly from a part-task training regimen. Part-task training involves taking a complex task and

K.L. Shapiro, J. E. Raymond

separately

training

each

of

/ Training oculomotor strategies

the

important

component

241

parts

before

reconstructing the part tasks into the whole task. Typically, part-task training has included components such as cognitive and motor performance features. While the visual features of a task usually are considered to be important, part tasks typically are not designed with the oculomotor requirements of the whole task in mind. The results of our present research suggest that there are two active components of the visual perceptual system which can be brought under voluntary control by incorporating each into an oculomotor part-task training regimen: (1) the oculomotor system, which acts to place both moving and stationary objects on the fovea, and (2) the visual attentional system which acts to maximize the use of fovea1 and peripheral visual sub-systems. The visual attentional system is important for inputing visual information from each of these two components of the visual system in selective situations where simultaneous input is necessary. For example, fovea1 input is required to manipulate an object requiring fine motor control, while the peripheral system is best suited for detecting the appearance of peripheral objects which require only that their presence be detected. The results of our investigation suggest that oculomotor task requirements in addition to the more traditionally considered motor task requirements should be analyzed when designing part-task training regimens. Such considerations may enhance the efficacy of part-task training procedures by pointing out a broader scope of perceptual motor behaviours contributing to complex perceptual motor task training.

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