3B Scientific Inverting Spectacles User Manual

3B SCIENTIFIC

Inverting Spectacles U8476730

Instruction Sheet

12/06 ALF

®

PHYSICS

1. Safety instructions

Wearing the inverting spectacles disrupts your
sense of orientation and balance. Wearing them for
long periods can cause dizziness and nausea.

Another person must always be present to help a
student doing the experiments if it becomes
necessary.

• Never allow an experimenter to wear the

inverting spectacles without supervision.

• Always be in a seated position when putting on

or taking off the inverting spectacles.

2. Description

By experimenting with inverting spectacles it is not
only possible to see how inverting prisms work but
also to gain a better understanding of human
vision and the role of the brain therein.

The instrument consists of two 90° isosceles prisms
set in an otherwise screened goggle frame made of
flexible plastic such that the prisms can be rotated
through 360°. This results in a lateral inversion of
incoming light beams so that the image can be
turned upside-down or be transposed left to right.
Ventilation holes are provided in the frame of the
spectacles to stop the prisms misting up. An elastic

strap that can be adjusted to match the
circumference of the head holds the inverting
spectacles in place. The spectacles are supplied in a
carry case lined with foam rubber.

3. Basic principles

Scientists have carried out many experiments with
inverting spectacles since the end of the 19th
century. Many such experiments involve studying
how the brain can adapt to the inverted image and
learn how to correct its perception accordingly.

When wearing the spectacles, the prisms can turn
what you see upside-down so that the world itself
seems to be standing on its head. This can cause
unexpected problems in doing the simplest things,
such as reaching for objects, drawing, or simply
getting oriented in space.

Nevertheless, it has been observed that after
wearing the spectacles continuously for a sufficient
time (about 2 to 3 days), people eventually become
adapted to them and regain the ability to deal with
things normally. Their view of the world rotates
back into its normal position so that up is once
again up and down is back to being down.
Experimenters then see things exactly the same as
before putting on the inverting spectacles. This

1

indicates that the link between the sensing cells of
the retina and the region of the brain that
processes optical information is not fixed at birth
but is formed by a learning process.

If the spectacles are then removed after being worn
for a long time, the world appears upside-down
again. However, perception then returns to normal
relatively quickly.

4. Operation

• When adjusting the prisms, do not touch the

glass surfaces.

• Ensure that the prisms are set parallel to each

other.

Adjusting the prisms:

5. Sample experiments

1. Drawing and writing on a blackboard

2. Reading “mirror writing”

3. Seeing, grasping and balancing objects

4. Throwing and catching a ball

5. Fill a container with water and pour water into
another container

6. Maintenance

• To clean use a soft damp cloth.

• Only use mild cleaning agents that do not

contain alcohol or solvents.

To make the image appear upside-down, set the prisms
as shown above (side view of spectacles)

To invert the image right to left, set the prisms as shown
above (top view of spectacles)

Should the prisms loosen in the frame after a
while, tip the frame forward and tighten the
securing ring.

Elwe Didactic GmbH • Steinfelsstr. 6 • 08248 Klingenthal • Deutschland • www.elwedidactic.com

3B Scientific GmbH • Rudorffweg 8 • 21031 Hamburg • Deutschland • www.3bscientific.com

Technische Änderungen vorbehalten

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