Unit 4 - Sensory-perceptual development

Sensation vs Perception

SENSATION:

Detection of stimull by sensory receptors and the transmission of this information to the brain (Shaffer & Kipp, 2013).

PERCEPTION:

The process by which we categorise and interpret sensory information (Shaffer & Kipp, 2013).

How infants are studied to identify their sensory capacities

• In the second trimester of the pregnancy, all senses begin to function. There is empirical

  evidence that the foetus learns and remembers.

Researchers observe the time of fixation on a stimulus or

the shift of attention from one stimulus to another:

• It is interpreted as a preference or attraction

for that stimulus.

• Use infrared devices that record the visual

path followed in scanning a stimulus.

• Physiological measurements: brain activity,

heart rate, respiratory rate, skin conductivity,

etc.

• They are interpreted in terms of stimulative impact.

Behavioural measures:

• Number of smiles

• Hand or eye movements

• Facial or vocal expressions

• Suction rate or large amplitude suction

• Reflex response (for tactile or light sensitivity)

Touch and pain

• Tactile sensitivity is the first sense to develop and the most mature sensory system during the first months.

• The newborn is also sensitive to pain, humidity and temperature changes

• The neonate's tactile perception (active use of touch for exploration) is organised around the mouth. This shifts at around 1 year of age, as the child begins to prefer using sight.

Smell and taste

• The sense of smell is also very acute from birth.

• They also seem to recognise the smell of their mother (especially those who are breastfed) and/or breastmilk (even if it is not their mothers).

• Taste begins to develop in the womb and it is strongly developed from birth.

• Through the amniotic fluid and through breast milk, babies experience tastes depending on the food the mother eats

Note:

Early exposure to a variety of tastes and textures can broaden and diversify food preferences in infants, making them less restrictive. Window of food acceptance: 6-18 months.

Vestibular sensitivity and hearing

• Vestibular sensitivity refers to the ability to detect gravity and the movement of our body (It helps us to maintain our posture and balance).

• Neonates like to be rocked and not like to be upside down.

• The newborn responds to auditory stimulation. The infant discriminates sound qualities (pitch, timbre, loudness...). However, its absolute threshold is higher and its latency longer than that of older children

• The neonate discriminates the mother's voice from unfamiliar voices. The neonate however is more sensitive to low tones (bass) and can hear high-pitched tones at around 6 months of age.

Sight

• Sight is the least developed sense of the newborn. Only visual tracking of a moving object is possible from birth.

• Acuity (ability to see detail) and visual

  accommodation (ability to focus) will be adult-like

  between 6 months and 2 years.

• Colour perception is also poor at birth, although they prefer coloured stimuli.

Perceptual organisation

1. ORGANIZATION OF ELEMENTS INTO A WHOLE
   First the elements are grasped about to each other until the whole is seen as a totality.
   E.g.: eyes, nose, mouth... become a face.

2. PROPERTIES AND RELATIONSHIP OF THE OBJECT TO ITS CONTEXT
   The object's properties must be captured to discriminate between objects (flexible, malleable...) and to place it in context (spatial references, depth...) .

C) STABILITY AND CHANGE OF OBJECTS (Constants)

Awareness of the stability of the properties of objects regardless of the context (darker room) and the position from which they are viewed.

d) SENSORY INTEGRATION

Combination of the different sensory modalities of an object.

Perception of the object as a whole

• Initially the child can only perceive one stimulus at a time and requires an exposure time. To perceive them together, they must be close in time and space.

‒ 2m: The child is interested in the inside of faces and

objects.

‒ 6m: his perception follows Gestalt laws: he is able to

perceive the shape of an object as long as it

conforms to Gestalt laws:

• COMMON REGION: They move together.

• PRAGNANZ (GOOD FIGURE): Tendency to capture the most

finished, simple, closed forms...

• PROXIMITY: The proximity tends to be perceived as a whole.

‒ 6m: Discriminates faces (he gets scared and

recognises)

Depth perception

• Visual cliff experiment (Gibson & Walk, 1960): 2-month-olds perceive depth and react differently (heart rate). Crawling infants: perceive differences and risk (refusing to move across "the depth").

• 1-3 months: kinetic depth cues (those provided by a moving object).

• Collision trajectory: approach of an object (they throw their head back or put their hand in front of an approaching object).

• 4-5 months: binocular static cues (provided by static objects, when images from both eyes are merged and perceived in 3 dimensions).

• E.g.: they look longer at a sphere than at a flat disc.

• 6-7 months: monocular static cues (provided by objects that remain still and can be perceived even when viewed with one eye): convergence of parallel lines, hiding of distant objects by closer ones, variation in the relative size of objects - will try to reach closer objects more often than distant ones.

• From 11 months onwards, they begin to take some external elements beyond their own body as a spatial reference.

Sensory integration

Cross-modal exploratory relationships refer to establishing relationships between two or more sensory modalities

to explore the environment.

‒ It is completed in the first year of life, but some exist from birth:

• Ear-sight: looking towards a sound.

• Touch-sight-suction: Look at where the cheek has been touched and suck.

• Smell-sight: Look where the breastmilk smells.

• Sight-grip: Seeing a rattle and picking it up is achieved at 4-5 months.

• Cross-modal transfer: integration of information from different senses to form a coherent representation of an

object, to recognise and discriminate an object (e.g., visually recognising an object that has previously only been

explored by touch)

Attention

• A child's attention to a stimulus depends mainly on the characteristics of the stimulus (brightness, movement, complexity, novelty, etc.). This is true for all ages.

What is learned is how to regulate attention, which involves the following skills:

a) Attentional CONTROL: the ability to concentrate and maintain attention on something, avoiding

distractions.

‒ It increases steadily between 1 and 6 years. In preschool, the average time a child spends on

an activity is 7 minutes.

b) ADAPTATION: involves paying more attention to what is essential than to what is irrelevant, as well

as distributing attention based on performance.

‒ Evaluation tasks:

• Stimulus sorting (cards with squares, triangles, stars...)

• Dichotic listening tests

c) PLANNING of attention: involves logical systematicity in exploring and comparing objects.

‒ If two children of different ages are asked to check similarities and differences in drawings,

only the older one explores systematically before answering.

d) STRATEGIES to attend to the stimulus: e.g. read a more complex text more slowly.