3905 Chapter 4

David Hume (1711-1776)
- Strong empiricist who believed that every effect has a cause
- Hume argued the true value of this assertion cannot be deduced in a priori fashion, but only from experience, and only as a subjective necessity
- Hume awakens Kant from his slumbers

Immanuel Kant (1724-1804)
- Critique of Pure Reason
- Perception is an active process, the mind contributes to our reality.
- Kant agrees with empiricists regarding innate ideas not being viable
- However he believes that we have the acquisition of a priori knowledge

Offered a solution of Transcendental Idealism

States that there are two domains of knowledge.

External world: Objects in a state independent of human experience

Inner or phenomenal world: The mind's transformation of the outer world.

The mind localizes its experiences in space and time in intuition

Space: Not an objective, empirical property of the world. No empirical perception can give us the idea of ’space’. It is the subjective and logical precondition for representation of objects.

 Time: Not an empirical sensation, but a logical, a priori structuring principle. We cannot represent phenomena without the notion of time, but we can represent time empty of phenomena, therefore the idea of time is logically necessary.

- Our mind structures the outer world in a way which is interpreted by the inner wold.
- Every perception is
1) Raw Sense Data
2) The organizing and structuring of data by the mind

To experience a (physical) world of objects, we must be able to distinguish the temporal order of our experiences from the temporal order of events.

Law of Specific nerve energies (Believed in the 19th century)
- Each sensory nerve conveys only one sense which results in consciousness.

Hermann Helmholtz (1821-1894)
- Adopted doctrine of physiological mechanism
Believing that all physiological processes are to be undersood through physical and chemical processes.
Vs
Vitalism
-All living organisms have a nonphysical lifeforce.

Helmholtz believed that energy is conserved and released based on mechanistic principles
- Tested reaction time on frogs (Neural signalling)

Time needed to process signal
1. Sending signal
2. Transmit message to nerves
3. Time required for perception in the brain

Helmholtz began studying vision.
- Physical: Eye as an optical instrument
- Physiological: How an image on the retina conveys signals to the brain (Sensations)
- Psychological: How these sensations could be construed to meaningful perceptions.
Found imperfections in the eye which gave more Creedence to Kant

Developed the trichromatic theory

Helmholtz disagreed with Kant (spatial perception determined mainly by innate intuitions & categories; Nativism view) and believed sensation was innate but that perceptual processes are acquired through experience & learning (empiricist idea)

- Helmoltz believed that sensation was innate put perceptual processes are acquired through experience.

Ebbinghaus illusion: Our brain makes judgements about size using adjacent objects.

Helmholtz had 2 important contributions to psychology
1) Neurological processes which underpin mental functions can be studied
2) The mind operates via mechanistic principles to create reality

Fechner (1801-1887)