Development of the nervous system, which includes the sensory pathways, is not complete at birth. The impact of this on sensory development is difficult to assess, as it is difficult to design methods of demonstrating what babies can sense.
Piaget – Sensori-motor stage – chaos of early perception only makes sense when babies start to link their actions with their perceptions. Empiricist stance – but adds active construction to the process.
Core knowledge – Spelke – babies have a basic understanding physical objects, numbers at birth. Social knowledge – Meltzoff – babies are born with an understanding of faces and people as social objects.
Sensation- the interface between the person and the environment. Receptors, such as eyes and ears are active – not passive like cameras or microphones. Pre- processing performed before information reaches the brain – Hubel – work on cat’s retina demonstrates this.
Perception – a mental construction of the world, generated through the senses. Several sources of evidence suggest babies perceive the world differently to adults – but very difficult to test as they can’t communicate.
Cognition – The relating of a current perception to previous perceptions – e.g. recognition of family members. Cognition is inferred from behaviour – cannot be determined directly. Each new perception has the ability to modify previous perceptions – therefore cognition can change over time.
Behaviour – One of the products of cognition, directly observable. Differences in behaviour are used to infer what is being perceived.
The Sensation -> Behaviour System
Substantial development occurs during childhood => perceptions of a baby are very likely to be different to those of an adult.
The system is not linear. Sense organs are direct-able – therefore we can choose what we want to perceive to some extent. Selective attention occurs – therefore, can regard sensation and perception as a product of behaviour. As this is a dynamic system, it makes it difficult to study the way one part of the system works from another.
There is significant development during the first few months of life; but at birth it is good enough for recognition and discrimination to be possible.
At birth, the eye is nearly mature – but infants have slow and inefficient accommodation (ability to focus the eye on objects at different distances).
Cones help the eye sense detail; rods provide sensitivity to light and dark. No new rods or cones formed after birth but the migration of cones to the fovea is only complete at age 11 (Abramov et al). Means that fine detail (acuity) and colour perception not mature (Hainline) [– blur and pastels].
Optic nerves lack myelin – means that information travels more slowly to the brain and gets diffused. Myelination is complete by about 3 months (Yakovlev & Lecours).
LGN compares inputs from adjoining nerve fibres and so respond to…