Saccadic masking is a visual illusion where the brain selectively blocks visual processing during eye movements called saccades. Saccades occur 3-5 times per second and last 10-30 milliseconds, during which time humans are effectively blind. The brain has two options - keep vision black during saccades until they stop, or retain the previous image and freeze time interpretation until the next image is processed. By freezing time interpretation during saccades, the brain can make the next few milliseconds seem shorter and catch back up to normal time perception, fooling us into thinking we can see continuously when we are actually blind briefly with each saccade. Saccadic masking explains why spirals or letters appear to move when we shift

1. Presented by Abin Nazar
Biotechnology and Biochemical Engineering (2017-2021)
Sree Chitra Thirunal College of Engineering, Pappanamcode,Tvm

3. SACCADIC MASKING

4. Find me the 2
anticlockwise rotating
spirals

6. Yes, all the spirals are actually static, focus on one spiral to find out. They appear to move
as our eyes saccade from one spiral to another due to a phenomenon called Saccadic
masking

7. ??????.....

8. You are blind
for 40min -
1hr everyday
with both your
eyes open

9. SACCADIC MASKING/VISUAL SUPPRESSION
● Saccadic masking is a visual illusion where the
brain selectively blocks visual processing duriing
every saccade
● A Saccade is a quick simultaneous movement of
both eyes between 2 or more phases of fixation
points in the same direction
● Our eyes saccade 3-5 times every second
● Length: 3.2°
● Time: ≤10-3 sec
● Angular speed: 10°/s- 300°/s
● Humans are blind during saccadic movement of
eys

10. 2 OPTIONS FOR OUR BRAIN
1)Keep the vision
black during the
saccade untill the
movement stops
2) Retain the image
before the onset of the
saccade during the
movement untill the
next steady image

12. HOW CAN WE SEE SOMETHING BEFORE
WE ACTUALLY SEE IT???
You simply play with
time!
SNAPS
HOT
OUTRUN
As our eyes starts to saccade,our brains feezes it's
interpretation of time until the saccade is
completed and the next clear visual gets
interpreted by brain. But we are lagging in time as
we froze time during saccade, so the brain
interprets the next milli seconds shorter and
thereby catch-up with normal time. Our brain fools
us every milli second because the truth that we are
blind during short milliseconds long intervals will
scare us.

13. 2 FLAWS OF VISION
???
● Lack of visual
acuity/sharpness
outside the
centre of vision
● Saccadic
masking

16. The visuals of previous 3 slides are actually static and they appear to move due Saccadic
masking

17. A B C D
E F G H I
J K L M
N O P Q
R S T U
V W X Y
Z
Read the letters and then shift your
focus to the clock. The first second you
observe is longer than the rest due to
Saccadic masking!

18. THANK YOU