Psychology 475/575
Cognitive Development
Dr. Lou Moses

MIDTERM 1 Answer Key

1. Lectures; text (p 32)

In the habituation phase, one of the stimuli is presented repeatedly over trials to infants until they begin to lose interest (as measured, for example, by looking times – that’s the dependent variable). Then, in the test phase, the new stimulus is presented. If infants can discriminate between the stimuli we should see dishabituation (an increase in looking time) whereas, if they cannot, they should remain habituated (looking times remain short). Graphs should reflect this.

2. Lectures; text (pp. 83-86)

A-NOT-B error: Place object several times under cloth A. Each time infant successfully retrieves object. Then, with infant watching, place object under cloth B. Infants in Stage 4 (8-12 months) will often continue to search under A

Piaget's interpretation: Infant does not have a fully developed object concept. In particular, infant does not have a conception of the object as existing independently of the infant's own actions. The infant thinks the object is brought back into existence by his or her actions and, in the past, these have involved lifting cloth A.

Alternatives: a) Memory -- only get the error if you enforce a short delay before search. In the meantime the infant may have forgotten where the object is; b) Search/ Motor skills. Maybe the infant does have a well developed object concept but does not have very good search skills or is unable to inhibit a well entrenched motor response (i.e., reaching at A).

3. Text (pp. 50-54)

Categorical speech perception refers to the fact that although certain speech sounds (e.g., “pa” vs. “ba”) form a continuous acoustic dimension, we tend to perceive them in a categorical discontinuous fashion (as either a “pa” or a “ba” but never as something in between).  Infants do have categorical speech perception.  Although infants initially perceive consonant contrasts from all the worlds’ languages they begin to lose their ability to discriminate sounds from languages other than their own between 6 and 12 months of age.

4. Baillargeon article in reader.

First pattern: When learning about a new physical phenomenon, infants first form an all or none concept that captures the essence of the phenomenon but few of the details. They later identify discrete and continuous variables that are relevant to the initial concept. Baillargeon offers several examples. For instance, in the case of support phenomena, at 3 months infants expect the box to fall if there is no contact but to remain stable if there is contact (all or none concept). Later they identify the relevance of a discrete variable (locus of contact) and a continuous variable (amount of contact).

Second Pattern: After identifying a continuous variable, first reason about it qualitatively and only later quantitatively. For example, in the case of collision phenomena, infants can predict the effect of modifications in the size of the cylinder only when they are able to encode such modifications in relative terms but not when they are forced to encode the cylinder sizes in absolute terms.

5.  Text (pp. 45-46).

Young infants do not show fear on the visual cliff when placed on the deep side. Instead they show heart rate deceleration, which is a sign of interest.  It is only around the time they begin to crawl that they show heart rate acceleration on the deep side, which is a sign of fear. Locomotion does seem to play a direct role in the onset of fear of drop-offs.  Infants who are not yet crawling but who are given locomotor experience (using walkers) are more likely to show fear than control infants.


6.  Lectures.

The 3 major principles we talked about were Priority (causes come before effects); Mechanism (there needs to be a mechanism linking cause and effect – temporal co-occurrence is not sufficient); and Determinism (all events have causes).

Piaget's view was that children did not develop an understanding of these principles until 8 or 9. Before that time he argued that they were indifferent to mechanism, often confused psychological with physical mechanisms, and thought that effects could occur before causes. The evidence for his view came from interviews with children about the causes of a variety of natural phenomena (e.g., the movement of the clouds and planets) and mechanical phenomena (how bicycles, steam engines work).

Alternative interpretations: Children might do poorly in these situations because they require relatively sophisticated verbal explanations or because the phenomena are highly unfamiliar ones or because the mechanisms are relatively opaque.

Recent evidence suggests that preschool children may have a beginning grasp of these principles. The Jack-in-the-Box experiment is relevant to Priority: ball in hole at time 1, jack pops up at time 2, ball in hole at time 3 – 3-year-olds understand that the first ball must be the cause. The Fred-the-Rabbit experiment is relevant to Mechanism: 3-year-olds understand that relevant (but not irrelevant) changes to the apparatus will effect the outcome. The Jack-in-the-Box experiment in which children witnessed a seemingly uncaused event is relevant to determinism – 3-year-olds were very surprised and searched for a possible cause.

7. Lectures; text (pp. 54-60)

Intermodal perception is the coordination of information from different sensory modalities into a coherent conceptual unity. Piaget argued that such perception did not develop until the end of the first year because, he argued, infants first needed to fully develop each of the individual senses before they could successfully integrate information across modalities. More recent evidence suggests that intermodal perception develops much earlier than Piaget thought. This evidence comes from studies looking at infants’ ability to integrate sights and sounds (e.g., in preferential looking studies they will look to the video screen that matches the sound they are hearing), to integrate sight and touch (e.g., newborns look to the screen that matches the texture of the pacifier they have been sucking), and to integrate sight and proprioceptive information (e.g., the imitation experiments in which infants use information from their own facial muscle movements in matching the facial expression of an experimenter).