Can the human eye detect an offside position during a football match?
BMJ 2004; 329 doi: https://doi.org/10.1136/bmj.329.7480.1470 (Published 16 December 2004) Cite this as: BMJ 2004;329:1470
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1.
Nowadays, in real time,
nobody can spot and judge an offside, not even using technological media1.
2.
The keypoint of the offside in football is to do it "in the precise
moment when the ball is played2,3".
3.
In that moment, the Referee and the Assistant Referees eye should have
within their visual field five objects4: the ball, two players of the
attacking team and two players of the defending team.
4.
The human eye needs to perform saccadic and fixational movements in order
to detect those players5,7. Time is necessary to do that, but players
make profit and change their position meanwhile6.
5.
The offside is also incompatible with physical laws related to speed,
space, time and acceleration5,6,7.
6.
Conceptually, the offside requires stopping time6 to be
applied correctly. But this is something impossible, even with technical media1.
7.
A Referee does not make an error when he misjudges an offside: He is
physiologically unable to judge it5,7,8.
1.
Belda Maruenda,
Francisco. Is it possible to spot and judge an offside position during a
football match?
http://www.bmj.com/cgi/eletters/329/7480/1470#166854
2.
International Football
Association Board. New Laws of the game. Zurich:
Fédération Internationale de Football Association (FIFA), 2006.
http://www.fifa.com/en/regulations/regulation/0,1584,3,00.html
3.
Belda Maruenda,
Francisco. 1 July 2006: Offside rule in football was modified substantially.
http://www.bmj.com/cgi/eletters/329/7480/1470#162676
4.
Belda Maruenda,
Francisco. Can the human eye detect an offside position during a
football match? British Medical Journal. 2004, December 18; 329
(7480): 1470 -1472.
5.
Belda Maruenda,
Francisco. Physical Laws, Ocular Neurophysiology and offside rule. http://www.bmj.com/cgi/eletters/329/7480/1470#162680
6.
Belda Maruenda,
Francisco. Physical laws and Offside Rule.
http://www.bmj.com/cgi/eletters/329/7480/1470#165009
7.
Belda Maruenda,
Francisco. Visual sequence in a game of offside in football.
http://www.bmj.com/cgi/eletters/329/7480/1470#162974
8.
Belda Maruenda,
Francisco. Which probabilities have referees and Assistant Referees of
detecting an offside?
http://www.bmj.com/cgi/eletters/329/7480/1470#165007
Competing interests:
None declared
Competing interests: REFERENCES
The key factor in this rule
application is that the player must be in the offside position exactly in the
moment when the ball is passed from one of his team mates, not when he receives
the ball or when the ball is en route between the players1.
In order to achieve this axiom, it is necessary to stop time2
and to locate all the players who take part in that game in zero milliseconds.
If some time passes, although it is just 1msec, the players can change their
position in the pitch.
In an offside, the Referee
and the Assistant Referee may have within their visual field five objects3:
two attacking players, the last two players of the defending team and the ball.
The Referee and the AR's need time to detect an offside position, and this time
is mainly defined by the saccades (latency and duration) and the eye fixations4,5.
This is incompatible with the philosophy of football and with physics, because
the players have speed and acceleration to change their position within the
pitch in a specific amount of time, so that they cannot be located in the
original position, exactly when the ball was passed5.
When an offside is
misjudged, human mistakes are always mentioned. However, that is not correct. To
make a mistake means to carry out incorrectly an action that we are qualified to
do, and that we can carry out correctly. The Referee and the AR's are
physiologically incapable of detecting an offside4,5.
That is why they can just "get right" some of the offsides, because they have
50% of possibilities of judging correctly an offside6.
The Referee, the Assistant
Referees, the public at the stadium and the viewers at home have to perform
saccadic movements and fixations2,4,5.
A Referee and an AR may find
three different physiological situations in an offside game:
1. If
all the players who take part in an offside are not within their visual field,
they would never know if there is or not an offside.
2. When all the players are
located within the visual field, at least 230msec are needed to locate the two
main players in that game (the
player who the ball
was passed and the second
last defender).
3. If there are players who
are located more than 6 metres away or more than 6 metres closer to the Referee
or the AR, the eye needs to accommodate7, and this physiological
situation needs more than 1 second.
Which is the problem of
the offside rule that makes it impossible for the human eye and technological
media8
to detect it? The problem is a notion error, because when it was created,
nobody took into account the time needed to locate the different players who
take part in the game. That time is fantastically used by the players to change
their position in the pitch, so that they cannot be detected exactly in the
precise moment when the ball is being passed.
The
offside rule in football was introduced9 in 1866 (19th century).
Since then, such a simple concept has gone unnoticed. Sometimes, the mankind has
needed centuries to understand very simple concepts and to accept them. We are
living in the 21st century, the century of technology and it is impossible to
detect and judge an offside, not even using technological media.
REFERENCES
1. Belda Maruenda, Francisco. 1
July 2006: Offside rule in football was modified substantially.
http://www.bmj.com/cgi/eletters/329/7480/1470#162676
2. Belda Maruenda, Francisco.
Physical laws and Offside Rule.
http://www.bmj.com/cgi/eletters/329/7480/1470#165009
3. Belda Maruenda, Francisco.
Can the human eye detect an offside position during a football match? British
Medical Journal. 2004, December 18; 329 (7480): 1470 -1472.
4. Belda Maruenda, Francisco.
Physical Laws, Ocular Neurophysiology and offside rule.
http://www.bmj.com/cgi/eletters/329/7480/1470#162680
5. Belda Maruenda, Francisco.
Visual sequence in a game of offside in football.
http://www.bmj.com/cgi/eletters/329/7480/1470#162974
6. Belda Maruenda, Francisco.
Which probabilities have referees and Assistant Referees of detecting an
offside?
http://www.bmj.com/cgi/eletters/329/7480/1470#165007
7. Caspi A, Beutter BR,
Eckstein MP. The time course of visual information accrual guiding eye movement
decisions. Proc Natl Acad Sci U S A. 2004 Aug 31; 101(35):13086-90.
8. Belda Maruenda, Francisco.
Which criteria should the technological media follow to detect an offside?
http://www.bmj.com/cgi/eletters/329/7480/1470#166690
9. Olivós Arroyo R. Teoría del
fútbol. Seville: Wanceulen, 1992.
Competing interests:
None declared
Competing interests:
As it happens with the human eye, the technological media are subjected to the
tyranny of the offside rule, because they have to detect all the players who
take part in this game "in the precise moment when the ball is being passed".
That is why physics play such an important role evaluating the media. The most
important premise is time and any technological media cannot consume time to
detect the players, because they can move within the pitch and they wouldn't be
in the initial position (when the ball was passed). So a media which does not
consume time should be used. Nowadays there is not such media, because the
electrical, electronical, radiofrequency or laser signal transmission needs
time. Will there appear a non time consuming media in the future?
Currently there is just a way
to know if a player was or not in an offside position, without any visual error.
We can only affirm that there was an offside or not repeating and freezing the
image on television, in the precise moment when the ball is being passed. In
that case, it would be necessary to stop the match to confirm the offside, time
which could be used for advertisements.
Competing interests:
None declared
Competing interests: No competing interests
Which distance in centimeters can a football player run in 200 milliseconds?
The problem arises when we apply Physical laws to the Offside and to the Occular Neurophysiology: speed, space, time and acceleration are incompatible with this rule application.
In order to obtain these data, I have used the results of the final race of the 100 metres flat race of the 1997 World Championship in Track and Field, which took place in Athens1, Greece. I compare the average results of the eight finalist athletes with the results of a football player who would have run 100 metres in 13 seconds, quite a slow speed for a professional player (Table 1). The distance ran by the football player in the first 10 metres is the addition of the reaction time plus the time needed to run those 10 metres.
From the results in Table 1 we can deduce that while the eyes of the Referee and of the Assistant Referee (AR) need 230msec2 to detect the player who the ball was passed and the second last defender, both of them may have changed their position in the field from the moment when the ball was passed. This distance will be of 76.05cm in 200msec if they started from a static position, depending on how the players speed up, or of 165.29cm if the players were already running.
These data have an added value if we take into account that, generally, the forward player runs to the opposite field, and the defender to the center of the pitch, to try to play an offside position on the forward player.
In position A, Fig.1 (Relative change in the players' locations in an offside position), we see a player who is not in an offside position exactly in the moment when the ball is passed from one of his team mate, because he is 1 metre away from the second last defender. However, if both players run in opposite directions, 200msec later, in position B the forward player is located 52cm before the defender (they start the race from a static position); and in position C he is located 2.30m before the defender (both of them are running). In situation B and C the player starts from a correct position, but, 30msec later, when the Referee or the AR would finish the saccadic sequence, they would say that there is an offside, when it is not true.
Fig. 1. Relative change in the players' locations in an offside position.
AR´s try to solve the problems of this rule appliance with two mistaken techniques.
1. Some AR´s try to run next to the first player who is playing the ball. However the AR has to carry out saccades continuously to detect the moment when the ball is passed and the geographical location of the fastest player. In the precise moment when the ball is being passed, the AR has to look again to that player, but during the period of the sequence fixation-saccade-fixation the player has the opportunity to change his position in the pitch.
2. The rest of the AR´s are just looking at the first player and they try to listen to the sound of the kick to the ball in the moment when the ball is going to be passed. But this means an additional problem, because the speed of sound is slower than the speed of light and during that time difference (during the time that takes the ear in perceiving the sound of the ball), the first player may have changed his position.
REFERENCES
1. Brüggemann, GP, Koszewski D, and Müller H (Editors). Biomechanical Research Project Athens 1997. Final Report. Oxford, UK: MMSU, 1999.
2. Belda Maruenda, Francisco. Visual sequence in a game of offside in football. http://www.bmj.com/cgi/eletters/329/7480/1470
Competing interests:
None declared
Competing interests: No competing interests
Reckoning the probabilities that
Referees and AR's have of "getting right" an offside can be quite a difficult
job, because they depend on a series of too wide and maybe infinite variables.
From these variables, we can underline: the attention on the game, the
floodlighting, the luminosity or the colour of the players' t-shirts, the
stripes on the grass, how the Refere and the AR1 are located during
the game, the insertion of other players in the game... However, in the last
analysis, and despite all the variables, a player can be in an offside position
or not. For the referee it is "heads or tails" and, as he is not capable of
spotting it, he has to make a decision with just two possibilities. That means
that Referees and AR's always have 50% of probabilities to "get an offside
right", but also 50% of errors.
It is possible to get the
minimum distance which separes both players (the first player and the second
last defender) so that the Referee and the AR's can detect an offside position
with no visual error. This distance is calculated in Table 1 for 230msec, the
time that the eye needs to detect the two main players, taking into account
their speed, if they start from static positions (start of the race speeding up)
or if they are already running, and if they stand up statically (they do not
move).
|
Z |
1. X: ► A Y: ◄ A |
2. X: ► A Y: ◄ |
3. X: ► C Y: ◄ |
4. X: ► C Y: ◄ C |
|
Space |
>174.92cm |
>277.54cm |
>277.54cm |
>380.16cm |
|
Z |
5. X: ► |
6. X: ► C Y: E |
7. X: ◄ A Y: E |
8. X: ◄ C Y: E |
|
Space |
>87.46cm |
>190.08cm |
>87.46cm |
>190.08cm |
|
X: A: C: Race: The player is in the middle Z: Relative positions of the players ► Direction: To the opposite goal. ◄ Direction: To the middle of the E: The player is in a static 7 y 8: The forward player, in an pitch, to avoid the |
||||
Table 1. Minimum distance which separes both players to be
able to see and judge
an offside position avoiding visual errors.
As we can see in Table 1, the minimum
distance that separates these two players to detect an offside has to be bigger
than 87.46cm (position 5). In this position the forward player runs to the
opposite goal, speeding up from a static position and the second last defender
is static, with no movement.
REFERENCES
1. Oudejans RR, Verheijen R, Bakker FC, Gerrits JC, Steinbruckner M, Beek
PJ. Errors
in judging 'offside' in football. Nature. 2000 Mar 2;404(6773):33.
Competing interests:
None declared
Competing interests:
Five objects1 take part in
an offside game: the ball, two attacking players and the last two players of the
defending team. Although more players can take part in some cases.
The offside rule requires that
the human eye detects the exact geographical location of all the players that
take part in a game, "in the precise moment when the ball is being passed2".
The fixational point of the Referee and the Assistant Referee (AR) should always
be the player who is touching the ball, in order to know the precise moment when
the ball is passed. This physiological situation requires that in the precise
moment when the ball is being passed, the eye should carry out at least three
saccades3,4: the first one to locate the player who receives the
ball, the second one to locate the second last defender and the third movement
to locate the last defender (because sometimes the goalkeeper has left the goal
and he is not the last defender).
After each saccade an eye ocular
fixation5 is necessary to acquire and to integrate all the visual
information of the player the Referee is interested in.
All that information must be
processed5,6,7 in the human brain and moreover to decide what players
participate actively in a game of offside8,9.
The visual sequence is the
following (Fig.1). The player who is playing the ball, and who is moving, is
spotted thanks to smooth pursuit eye movements10. In a probable
offside game, in the moment when the ball is passed, the Referee and the AR
carry out a first fixation movement11 (which lasts 30msec). Then,
they get all the information, which is processed in the brain and at the same
time the Oculomotor System prepares to carry out several consecutive saccades12,
to detect the exact geographical position of all the players who take part in
that game in the football pitch. After the first fixation movement, the first
saccade3,13,14 is carried out (duration: 80msec of latency + 30 msec
of duration) which finishes with the second fixation. The second fixation
(duration 30msec) is carried out to process the exact geographical location of
the player who is going to receive the ball. After the second fixation, the
second saccade starts (duration 30msec) which finishes with the third fixation
of the second last defender (duration 30msec), to obtain visual information to
know his relative position compared to the player of the opposing team who
received the ball and to detect if there is an offside or not. If the goalkeeper
is not the last defender, it is precise to carry out a third saccade (duration
30msec) and a fourth fixation (30msec) in order to locate the last player of the
opposing team. All this process is 230msec long up to the third fixation and 290
msec long up to the fourth fixation (Fig.1. Game A: Offside position. Game B:
There is no offside position. The visual sequence is the same in both games).
In order to carry out this
saccadic sequence, all the players must be within the visual field. If any of
the players is not within it, it would be necessary to move the head to locate
the players. And that would mean that the amount of time to detect the players
would obviously be higher.
To have a wider visual and
graphical knowledge about saccades, fixations and smooth pursuit eye movements,
it is advisable to read the web page from the University of Western Ontario15,
Canada.
REFERENCES
1.1. Belda
Maruenda, F. Can the human eye detect an offside position during a football
match? British Medical Journal. 2004, December 18; 329 (7480): 1470
-1472.
2.2. International Football Association Board. New Laws of the
game. Zurich: Fédération Internationale de Football
Association (FIFA), 2006.
http://www.fifa.com/en/regulations/regulation/0,1584,3,00.html
3.
3. Fischer B, Biscaldi M, Gezeck S. On the development of voluntary and reflexive
components in saccade generation. Brain Research, 1997; 754:285-297.
4.
4. Brockmole, J. R., Carlson, L. A., & Irwin, D. E. Inhibition of attended
processing during saccadic eye movements. Perception & Psychophysics.
2002; 64, 867-881.
5.5. Martinez-Conde, S., Macknik, S.L., Hubel,
D.H. The role of
fixational eye movements in visual perception. Nature reviews Neuroscience,
2004 (5):229-240.
6.6. John
M. Findlay, Valerie Brown, Iain D. Gilchrist. Saccade target selection in visual
search: the effect of information from the previous fixation. Vision
Research, 2001; 41: 87–95.
7.
7. Becker, W. & Jurgens, R. An analysis of the saccadic system by means of double
step stimuli. Vision Res. 1979; 19(9):967-83.
8.8. Blohm
G, Missal M, Lefevre P. Processing of retinal and extraretinal signals for
memory-guided saccades during smooth pursuit. J Neurophysiol. 2005
Mar; 93(3):1510-22.
9.
9. Colonius H, and Arndt P. A two-stage model for visual-auditory interaction in
saccadic latencies. Percept Psychophys. 2001; 63: 126-147.
10.10. Blohm G, Missal M, Lefevre P. Direct evidence for a position input to the
smooth pursuit system. J Neurophysiol (February 23, 2005). doi:10.1152/jn.00093.2005.
11.11. John M. Findlay, Valerie Brown, Iain D. Gilchrist. Saccade target
selection in visual search: the effect of information from the previous
fixation. Vision Research, 2001; 41: 87–95.
12.12. Caspi A, Beutter BR, Eckstein MP. The time course of visual
information accrual guiding eye movement decisions. Proc Natl Acad Sci U S A.
2004 Aug 31; 101(35):13086-90.
13.13. Rayner, K. Eye movements in reading and information processing: 20 years
of research. Psychological Bulletin, 1998; 124: 372- 422.
14.14. Sooha Park Lee, Jeremy B. Badler, Norman I. Badler. Eyes alive.
SIGGRAPH 2002: 637-644.
15.15. The University of Western Ontario. 2003.
http://www.physpharm.fmd.uwo.ca/undergrad/sensesweb/L11EyeMovements/L11EyeMovements.swf
Competing interests:
None declared
Competing interests: No competing interests
On 1 July 2006 the new Laws of the Game -1- (IFAB, 2006), modified at
the 119th International Football Association Board (IFAB) meeting in
London, England on 26 February 2005, comes into force.
Offside rule in football (soccer in USA) was modified substantially.
Now, the key factor in this rule application is that the player must
be in the offside position (Fig. 1) exactly in the moment when the ball is
passed from one of his team mates, not when he receives the ball or when
the ball is en route between the players. Moreover, it is not an offence
in itself to be in an offside position. A player in this position is
penalised only if he is, according to the referee, involved in active play
by interfering with play, interfering with an opponent, or gaining an
advantage by being in that position.
Offside errors -2,3,4- in football are very frequent, but: the human
eye and the brain are enabled physiologically to spot and judge an offside
in football?
At the present time, there are several companies of modern technology
in the world that are investigating technological media to detect an
offside in football in real time.
References
1. International Football Association Board. New Laws of the game.
Zurich: Fédération Internationale de Football Association (FIFA), 2006.
http://www.fifa.com/en/regulations/regulation/0,1584,3,00.html
2. Helsen W, Bilis B, Weston M. Errors in judging "offside" in
association football: test of the optical error versus the perceptual
flash-lag hypothesis. J Sports Sci. 2006 May;24(5):521-8.
3. Baldo MV, Ranvaud RD, Morya E. Flag errors in football games: the
flash-lag effect brought to real life.Perception. 2002;31(10):1205-10.
4. Oudejans RR, Verheijen R, Bakker FC, Gerrits JC, Steinbruckner M,
Beek PJ. Errors in judging 'offside' in football. Nature. 2000 Mar
2;404(6773):33.
Competing interests:
None declared
Competing interests: No competing interests
In order to detect an offside in real time, without possibility of
physiological or technological error, the current text of the Offside Rule
demands the active participation some Physical Laws and all the present
knowledge on Ocular Neurophysiology.
PHYSICAL LAWS AND OFFSIDE RULE
The offside rule is directly related to some physical concepts:
speed, space, time and acceleration. The human eye needs time to carry out
the eye movements; players run at a different speed and they cover
different spaces in the playing field as the eye tries to locate the exact
position that those players had in the field "in the precise moment when
the player who has the ball passes it". The acceleration in each players'
race allows them to run a specific space in the pitch in some second
tenths.
OCULAR NEUROPHYSIOLOGY AND OFFSIDE RULE
The peripheral retina gathers information that the brain uses to
program the eye movements, basically from the parafoveal area -1,2,3-.
In a football match the saccadic eye movements are those used between
two players, to look at each other. In the offside, saccades are used when
the ball has already been passed, to locate all the players that take part
in a game (if they are all within the visual field).
A saccadic movement needs time that depends on the latency -4-
(duration 80-135 miliseconds) and duration of the saccadic movement -5,6-
(between 30 and 100 msec: A 40º saccade -6- requires 110 msec, 40 msec for
7'5º and 30 msec for 2º saccade -7-).
The cognitive process to acquire and to process all the visual
information of the object in the visual field and to decide which is the
following object of interest is performed during ocular fixation -8-. The
duration of ocular fixation can be extremely brief -9-: about 40 or even
30 msec.
Eye accommodation is the capacity that the eye has to focus. Within
the visual field, when we want to change the fixation point from a far
object to another one located at less than 6 metres from us, the
crystalline changes its convexity -10-. Normal latency as well as duration
appear to have a large interindividual variability -11-. The normal
response latency is of 394 ms (± 46 SD). In order to change the focus from
a far to a close object, 640msec. are needed, and viceversa (from a close
to a far object), it takes 560ms -12,13-.
In an Offside game, if there are players located further than 6
meters away from the Referee or the AR and other players located at less
than 6 metres, they have to carry out the Eye Accommodation.
When the eye moves, several anatomical structures of the human brain
-14,15- take part. The function of these structures is to process at the
same time -9,16- all the information gathered during the fixations -8-,
store it -17- and integrate it, as well as to program the following eye
movements -18-. The combined presentation of auditive and visual stimuli
reduces saccadic latency -19-.
References
1. Rayner, K., & Fisher, D. L. Letter processing during eye
fixations in visual search. Perception & Psychophysics. 1987; 42: 87-
100.
2. Findlay, J. M. Saccade target selection during visual search.
Vision Research. 1997; 37: 617-631.
3. Hooge, I. T., & Erkelens, C. J. Peripheral vision and
oculomotor control during visual search. Vision Research. 1999; 39: 1567-
1575.
4. Fischer B, Biscaldi M, Gezeck S. On the development of voluntary
and reflexive components in saccade generation. Brain Research, 1997;
754:285-297.
5. Brockmole, J. R., Carlson, L. A., & Irwin, D. E. Inhibition of
attended processing during saccadic eye movements. Perception &
Psychophysics. 2002; 64, 867-881.
6. Rayner, K. Eye movements in reading and information processing: 20
years of research.Psychological Bulletin, 1998; 124: 372- 422.
7. Sooha Park Lee, Jeremy B. Badler, Norman I. Badler. Eyes alive.
SIGGRAPH 2002: 637-644.
8. Martinez-Conde, S., Macknik, S.L., Hubel, D.H. The role of
fixational eye movements in visual perception. Nature reviews
Neuroscience, 2004 (5):229-240.
9. John M. Findlay, Valerie Brown, Iain D. Gilchrist. Saccade target
selection in visual search: the effect of information from the previous
fixation. Vision Research, 2001; 41: 87–95.
10. Schachar Ronald A.; Bax Andrew J. Mechanism of Human
Accommodation as Analyzed by Nonlinear Finite Element Analysis. Compr
Ther. 2001 Summer; 27(2):122-32.
11. Beers AP, van der Heijde GL. Analysis of accommodation function
with ultrasonography. Documenta Ophthalmologica. 1996-97; 92(1):1-10.
12. Moses RA. Acomodación. In: Fisiología del ojo de Adler. 8th ed.
Buenos Aires: Panamericana, 1988:285-302.
13. Morris A, Temme LA. The time required for U.S. Navy fighter
pilots to shift gaze and identify near and far targets. Aviat Space
Environ Med. 1989 Nov; 60(11):1085-9.
14. Horwitz GD, and Newsome WT. Separate signals for target selection
and movement specification in the superior colliculus. Science. 1999; 284:
1158-1161.
15. Dorris MC, and Munoz DP. Saccadic probability influences motor
preparation signals and time to saccadic initiation. J Neuroscience. 1998;
18: 7015-7026.
16. Becker, W. & Jurgens, R. An analysis of the saccadic system
by means of double step stimuli. Vision Res. 1979; 19(9):967-83.
17. Caspi A, Beutter BR, Eckstein MP. The time course of visual
information accrual guiding eye movement decisions. Proc Natl Acad Sci U S
A. 2004 Aug 31; 101(35):13086-90.
18. Blohm G, Missal M, Lefevre P. Processing of retinal and
extraretinal signals for memory-guided saccades during smooth pursuit. J
Neurophysiol. 2005 Mar; 93(3):1510-22.
19. Colonius H, and Arndt P. A two-stage model for visual-auditory
interaction in saccadic latencies. Percept Psychophys. 2001; 63: 126-147.
Competing interests:
None declared
Competing interests: No competing interests
In his paper “Can the human eye detect an offside position during a
football match?” Francisco Belda Maruenda concluded that it is beyond the
capacity of the referee’s two human eyes to keep in his visual field at
least five objects at the same time – the two players of the attacking
team, the last two players of the defending team, and the ball. In this
way, he provides an explanation for the relatively high proportion of
“bad” offside decisions detected by the television analysts.
He suggests that the use of modern technology is required to limit
these errors. I would like to suggest an alternative approach using the
same number of officials but based on the combined workings of four eyes
and not just two.
New Proposal
My starting point is that to be offside requires all of three criteria to
be met:
1. At the time when the ball was last played by an attacking player, at
least one attacking player is in an offside position (“timing”)
2. At least one attacking player is nearer the defender’s goal line than
at least two defending players (“position”)
3. At least one attacking player in an offside position is “actively
involved” with the play (“interfering”).
Under the present method of implementing the offside rule, the
assistant referee (linesman) raises his flag when he considers all three
criteria met. The referee will take the judgement of the assistant
referee into consideration as well as his own before deciding whether to
blow his whistle and give an (indirect) free kick for offside, or not .
In my view it would be more satisfactory and lead to a higher
proportion of correct decisions to let the assistant referee make the
decisions regarding “position” and “interfering”, and leave it to the
referee to decide on “timing”. The assistant referee would raise his flag
when there were less than two defenders between the most advanced attacker
and the goal line. Where the ball is, who plays it and to whom it is
passed is irrelevant in deciding what the assistant referee does. The
referee is following the ball and when he sees the attacker about to, and
actually kick, the ball he looks up to the assistant referee:
- If the flag was up, is up and stays up, the referee blows his
whistle for offside.
- If the flag was up and was coming down after the ball was played,
the whistle is blown. A defender or an attacker (or both) have almost
certainly moved back after the ball was played.
- If the flag was down but is raised as and after the ball is kicked,
the referee does not blow for offside. The attacker has most probably
broken through to be in an offside position after the ball was played.
- If the flag was down and stays down then clearly there is no
whistle.
In this revised approach, the referee’s eyes need to focus on just
the flag and the ball/passer’s boot. The assistant referee has to focus on
the position of one man relative to two others (generally this is a single
defender as the goalkeeper is the second defender).
Analysis
From the attacking side’s point of view, they do not want their attacker
A1 in the following position to be assessed as being goal side of defender
D2 at the time the ball is kicked when
in reality he was not.
In the new approach to implementing the offside law, the referee (R),
aware of the possibility of an offside is monitoring A2, the ball and the
assistant referee (L). As I understand Maruenda (2005) , the delay
between seeing the ball kicked by A2 (in the general direction of A1) is
only 140ms because the latency penalty is not applicable. The referee
then looks in the direction of the linesman and sees the position and
motion of the flag – a saccadic movement taking, say, 200ms. That is a
total of 340ms before he makes his decision. During this time L has
observed the relative position of A1 and D2, taking 140 ms, and moved his
flag appropriately, after say 100ms; this gives a total of 240ms before
the R can correctly know A1’s “offside status”.
So in this example and on these assumptions, what R sees is the
“offside position” only 140ms after A2 became offside at a time 100ms (=
340-240ms) after the ball was kicked, considerably less than the times
quoted in Maruenda (e.g. 500 - 600ms). In fact this 100ms is the
difference between the time it takes for R to see L after the ball was
kicked, and the response time of the L in raising his flag. In this
example it has been implicitly assumed that L is quicker than the R, but
he might be much slower and this could result in a wrong decision (R eyes
would see the flag down).
Conclusion
If these the response times of the two officials were small and of
comparable magnitude (which seems a not unreasonable expectation given
training and practice) the decision of the referee would be taken in much
the same time frame as in a normal incident, for example, a possible late
the tackle.
The analysis suggests that the error rate on offside decisions would
be substantially reduced by the new approach. As a long term football
supporter (and especially of Arsenal) this would be very much welcomed!
An additional advantage is that all the players on the field would
know the current judgement of the assistant referees regarding the
position of the lead attackers. This should lead to fewer stoppages for
offside, adding to the continuity of play. It would help real time
communication between the players and officials, which in football is
noticeably absent – unlike rugby where the referee does advise players in
key situations to take remedial action or take the consequnces.
Competing interests:
None declared
Competing interests: No competing interests
Re:Conclusions: Offside Rule versus Ocular Neurophysiology and Physical Laws
I apologize for being late to this party. I am both a PhD student in
motion perception psychophysics and the State Director of Referee
Instruction in Ohio South. I have conducted a comprehensive review of the
parallax theory, the flash lag effect theory and the excellent
physiological observations of Dr. Maruenda. I want to throw my 2 cents
into the mix. The data don't support the contention that ARs get the call
right 99% of the time as the gentleman from York suggested. This value is
closer to 85%, based upon the 2002 world cup and the 2010 study of the FA.
There is no possibility of 100% accuracy in this case. The psychometric
functions of human performance 100% guaranty both FE and NFEs. The large
majority of these errors result either stoppages in game flow only (FE) or
attacks that dissipate on their own. Some result in dangerous corner kicks
and a very very few in goals. No number of eyes will solve this problem,
but assuming that we don't want to scrap the law altogether, or materially
alter it, there is a combination of eyes and technology that will be
minimally disruptive and available today, at least for high level games
where all the money is. It is comparatively easy to make the referees very
conservative with their flags with directives from the competition. Be
130% sure before you raise the flag or at least a meter off if they are
running (they do this already to an extent). This eliminates all but a
very few FE prematurely stopping play, but necessarily allows close
offside calls to be missed and play to continue. In those few cases of
offside that result in CKs or goal, the replay system as evidenced in the
recent world cup can review the offside using a FIFA or competition
appropriate AR. That takes about 10 seconds now. This review would
easily be completed before the next restart, and this might happen a
handful of times in a game (or not at all), at a point where the game is
already stopped. It is a great compromise to keep tech intrusion to a
minimum, but prevent egregious errors from ruining a match. It does not
prevent defenders from trying to trap, and would actually give them more
confidence that the AR could not allow a bad goal to happen. There are
plenty of 'forced retired' officials who would make lovely replay judges.
The cameras are already there for broadcasts - and if they aren't, no one
can refute the calls to begin with.
Competing interests: No competing interests