3B Scientific Inverting Spectacles - Manual

3B SCIENTIFIC® PHYSICS
1
Inverting Spectacles U8476730
Instruction Sheet
12/06 ALF
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