Sensory system

This essay will look at views on how Infants perceive the world. It will focus on the empiricist view and the natives view: we will try and understand how sensation, perception, cognition and behavior go hand-in-hand. The auditory and visual perception of infants including the importance of cross-modal perception. At birth the nervous system, which includes the sensory pathway has not yet been developed and It is therefore difficult to asses or understand what babies can sense.

There are different views and theories on how Infants perceive the world. The Empiricist view, in which Pigged suggests that the chaos of early perception only makes sense when babies start to link their actions with their perceptions. ‘ (Book 1 Chapter 3 Page 92) He called this the ‘Sensors-motor stage’ because he thought that the mall Important task for Infants to learn Is the link between sensation and movement. Piglet’s theory takes experience as the starting point of knowledge.

However, on the other hand the Natives view argues that infants are born with some basic knowledge and understanding. There are two different forms of this view which eve appeared over the years: “Core knowledge (Spells) babies have a basic understanding physical objects, numbers at birth. Social knowledge (Meltzer babies are born with an understanding of faces and people as social objects. ” (Book 1 Chapter 3 Page 92) Sensation, perception, cognition and behavior are an important system which go hand-in-hand.

Our knowledge of the world depends on our senses: vision, hearing, taste, smell, position, movement, balance, and touch. If someone bounces a basketball, our eyes and ears pick up stimuli such as light and sound waves and send neural signals to the brain. This process called sensation occurs when physical However, only when the signals come together meaningfully do we actually perceive a bouncing basketball. Perception happens when the brain organizes and interprets sensory information.

We then come on to cognition, this relates to not only registering a perception but associating it with any previous perceptions; so when we come across a bouncing basketball we link it back to any other time we have come across a bouncing basketball. Our behavior is then a reaction or response to what we have sensed, perceived and how it has related to any past experience. Audition is often treated as a secondary sensory system behind vision, but it is also very important especially to communicate. Hearing starts around 6 months pre-natal, at birth the anatomical structures mostly mature.

Hearing sensitivity gradually increases in the early years. Like vision, preference for some auditory stimuli is shown. Fernando demonstrated, ‘Mothers’ was preferred in 4 month olds over normal speech. We use changes in pitch and rhythm when we talk to children, and we emphasis important words This is what children usually learn and produce first. However, happy normal speech referred to unhappy Mothers (Page 113 Sings) This Just tells us how infants are able to respond at such a young age and they are able differentiate between a happy and unhappy voice.

Deceased and Fifer used sucking rates to control what an infant heard, baa and pa phonemes. Rates increase when first heard, habituation occurs and rates drop. Peak sucking doesn’t occur again on same phoneme re-presented later. Deceased and Spence also found evidence that newborns can hear in the womb (at birth the anatomical structures mostly mature), preference shown for a piece of prose read to them before birth demonstrated (Page 114). Babies can discriminate between different versions of [b] and [p] as they are not yet ‘native listeners’ until they are older.

Skuzzy found evidence that infants acquire knowledge about the nature of their native language long before they can speak; babies are able to tell apart sounds and speech then most adults. Developmental course of speech goes in two directions – less competence in distinguishing non-native sounds; but become more sophisticated in understanding the characteristics of their own language. At birth, the structure of an infant’s eye is nearly fully formed; but biologically it is dilled with constraints due to visual processes within the eye needing to mature.

However, by reviewing behavioral studies of infants up to 12 months old, we can see that not only are babies born with visual preferences that enable them to process ‘real life’ stimuli that they will encounter; vision can also be enhanced as infants develop, through experiences or actively constructing their own knowledge. The retina, the optic nerve, the visual cortex and the lateral genitals are the four main the retina (upside down) stimulating the visual receptors- cones, rods and ganglion cells.

Electro-chemical signals are then sent down optic nerve, which connects with the lateral genitals and ‘projects’ onto the visual cortex. Several sections of the visual system are constraint by immaturity; Firstly, there is not a high density of cones inside the fovea, these visual receptors sense color and detail and the lack of these will result in the infants vision being blurred and lack color intensity, It takes months to develop a mature status.

Scanning develops in first 2-3 months to become similar to adults, before then, infants look at far fewer parts of an image than adults Marker & Marker); when their visual system matures they are then able to view things in more detail. Faint reasoned if babies look at some things more than others they must be able to perceive differences between objects; Fantast’s Viewing chamber’ was used to observe at how long an infant would gaze a certain object. Karamazov- Smith – Visual processing starts with a vengeance’. E. . Studies show 12 hour old infant prefers looking at mother – can be apparent after an hour, gets stronger with experience (Bushnell Page 104). This is a familiarity preference. Clear evidence for novelty preferences – as habituation occurs. Size constancy – Slater found evidence that when habituated to a cube of one size they looked more at a new cube even though they were at different distances away to make the retinal image the same size. This is therefore an organizing feature of perception present at birth.

Occluded objects recognized from around 2 months. 5-6 months – two touching objects are not one object 6-8 months – have learnt about support & gravity Stereotypes emerges at around 3-6 months – near adult capability between 6-12 months Gibson and Walk invented the visual cliff examine depth perception in infants – 3/27 crawled over he drop; all 27 crawled over the visually solid side. This Just shows how aware such infants are of depth and when their mothers were on the other side.

Evidence that infants do have the ability to integrate vision and hearing – Worthier – immediately daughter born tended to turn her eyes right or left depending on which side a click was made. Moronically found infants could learn that sound was an attribute of an object only when the sound and visual object were in the same place. Slater found evidence that infants only learned sight-sound co-ordination when their on/off presentation was synchronized. Intercessory redundancy (linking information from one sense to another) – the ability to link two modalities.

Important example is voice to face – no obvious way in advance as to what face will produce a particular voice but at 3 months infants can work this out – particularly when the mouth can be seen moving (intercessory redundancy happening). At 11 weeks – infants expect a single object to make a single sound and a compound object a complex sound when dropped (Barrack). Barrack and Likelier suggest redundant information is important for infants when learning object names.

Research suggests preparedness at birth for leaning with dynamic perceptual experiences – much experimentation has been with less rich stimuli, which may underestimate what babies can perceive. Buttonholer – moving wall experiment with 15-34 month old infants – move wall towards child they fell over backwards, move it away they fall over forwards. Likely to be due to the vestibular system and kinesthesia feedback occurring. (e. G. Viewing a moving train from a stationary train). Similar expect in 2 month old infants found the same effect. Social referencing – looking to care givers to see what is safe/what isn’t.