Edge asks a question each year to prominent scientists and there question this year was “What have you changed your mind about and why?”. Well, they didn’t invite me to answer that question (not yet 🙂 , so I wont force my thoughts on the readers of this blog; but instead would like to highlight one of the answers (by Alison Gopnik).
She mentions that she though earlier that pretend play (and related to that the adult fiction reading/creation) was a spandrel and had no evolutionary significance. Now she thinks that the capacity for pretend play is necessary for imagination to develop whcih is necessary for creating new worlds. I, to say the least, am firmly entrenched in the view that treats pretend play as of fundamental importance to development and it is heartening to get support from a prominent psychologist.
I reproduce below the response of Alison in its entirety. (emphasis added by me)
Imagination is Real
Recently, I’ve had to change my mind about the very nature of knowledge because of an obvious, but extremely weird fact about children – they pretend all the time. Walk into any preschool and you’ll be surrounded by small princesses and superheroes in overalls – three-year-olds literally spend more waking hours in imaginary worlds than in the real one. Why? Learning about the real world has obvious evolutionary advantages and kids do it better than anyone else. But why spend so much time thinking about wildly, flagrantly unreal worlds? The mystery about pretend play is connected to a mystery about adult humans – especially vivid for an English professor’s daughter like me. Why do we love obviously false plays and novels and movies?
The greatest success of cognitive science has been our account of the visual system. There’s a world out there sending information to our eyes, and our brains are beautifully designed to recover the nature of that world from that information. I’ve always thought that science, and children’s learning, worked the same way. Fundamental capacities for causal inference and learning let scientists, and children, get an accurate picture of the world around them – a theory. Cognition was the way we got the world into our minds.
But fiction doesn’t fit that picture – its easy to see why we want the truth but why do we work so hard telling lies? I thought that kids’ pretend play, and grown-up fiction, must be a sort of spandrel, a side-effect of some other more functional ability. I said as much in a review in Science and got floods of e-mail back from distinguished novel-reading scientists. They were all sure fiction was a Good Thing – me too, of course, – but didn’t seem any closer than I was to figuring out why.
So the anomaly of pretend play has been bugging me all this time. But finally, trying to figure it out has made me change my mind about the very nature of cognition itself.
I still think that we’re designed to find out about the world, but that’s not our most important gift. For human beings the really important evolutionary advantage is our ability to create new worlds. Look around the room you’re sitting in. Every object in that room – the right angle table, the book, the paper, the computer screen, the ceramic cup was once imaginary. Not a thing in the room existed in the pleistocene. Every one of them started out as an imaginary fantasy in someone’s mind. And that’s even more true of people – all the things I am, a scientist, a philosopher, an atheist, a feminist, all those kinds of people started out as imaginary ideas too. I’m not making some relativist post-modern point here, right now the computer and the cup and the scientist and the feminist are as real as anything can be. But that’s just what our human minds do best – take the imaginary and make it real. I think now that cognition is also a way we impose our minds on the world.
In fact, I think now that the two abilities – finding the truth about the world and creating new worlds-are two sides of the same coins. Theories, in science or childhood, don’t just tell us what’s true – they tell us what’s possible, and they tell us how to get to those possibilities from where we are now. When children learn and when they pretend they use their knowledge of the world to create new possibilities. So do we whether we are doing science or writing novels. I don’t think anymore that Science and Fiction are just both Good Things that complement each other. I think they are, quite literally, the same thing.
Imagination refers to holding in mind a representation that may not be (yet) ‘true’ and does not necessarily reflect the facts about the external world or the Reality as of now. The act of imagination may use previous memories and a general knowledge of the world to recreate past memories or to imagine novel future events.
An article by Simon Baron Cohen, discusses the biology of imagination. Simon distinguishes between the contents of imagination , which are culturally determined; and the capacity for imagination, which is biologically grounded. He also focuses on imagination as a false or distorted representation of Reality as opposed to mere imagery, which though itself also being a mental representation, may more-or-less represent the world accurately.
Imagery may be necessary for human imagination. It has been suggested that all the products of the imagination are derived from imagery, following some transformation of the basic imagery. For example, Rutgers’ psychologist Alan Leslie, when he worked in London in the 1980s, proposed that imagination essentially involves three steps: Take what he called a ‘primary’ representation (which, as we have already established, is an image that has truth relations to the outside world). Then make a copy of this primary representation (Leslie calls this copy a ‘second-order’ representation). Finally, one can then introduce some change to this second-order representation, playing with its truth relationships to the outside world without jeopardising the important truth relationships that the original, primary representation needs to preserve. For Leslie, when you use your imagination, you leave your primary representation untouched (for important evolutionary reasons that we will come onto), but once you have a photocopy of this (as it were), you can do pretty much anything you like with it.
Thus, what Leslie contends is that the faculty of imagination involves a mechanism for making a second -order representation in the mind of a past stimulus (the imagery), in the absence of the stimulus in the here and now. Crucially, the faculty of imagination also involves the ability to modify the stimulus in such a way so that it no longer represents the original stimuli accurately. One , either creatively or mundanely , transforms some aspects of the original stimulus. to come up with something imaginary (like the concept of a unicorn). Thus, it seems there are three faculties involved- one for maintaining a second order representation of an object in absence of stimulus, another for distorting or manipulating that representation to come up with novel objects and the last for keeping this novel representation as different from the original representation to avoid confusion and loss with reality.
Leslie calls the abilities to form second-order representations and the ability to change or distort these representations as Meta-representation capacity and links this to the ability to indulge in pretend play in 9-15 months old infants and the ability for mind reading or false-belief or Theory of Mind (ToM) ability in older children (4 yr olds). The contention is that pretend play enables one to keep two copies (one primary and the second a false second-order representation) of an external object in mind simultaneously while at the same time enabling one to know that one is true and the other false or a pretense. Also pretend play involves treating one object (say a banana ) as another object (say a telephone) and thus develops the capacity to distort the second order representation of an object. This meta-representation ability in turn is the pre-requisite for imagining future outcomes and thus for successful planning in older adults.
Before I continue, let me pause and define imagination faculty in more rigorous terms for forthcoming discussions. We would be primarily concerned with the ability to shift focus from now and here to then and there and also from self to others. We would be concerned with imagination as depicted in scenarios involving people or objects with agency. Also please refer to this document by Buckner and Carrol.
Thus, the following kinds of imaginations are under preview:
- Remembering the autobiographical past (reconstructing past memories or imagining what it felt like ‘then’ in the past vis-a-vis ‘now’).
- Simulating the autobiographical future or Prospecting (constructing plausible future scenrie that would happen ‘then’ as compared to ‘now’)
- Navigating (constructing a scene that is ‘here’ (first person perspective) to ‘there’ (third person perspective)) Changes in spatial perspective – seeing things/ scenes from someone else’s point of view . Please keep in mind the distinction between two types of spatial point-of-view taking – one involving line tracing and the other perspective taking). It is my contention that while normal kids would rely more on perspective taking, the autistic children rely on line tracing for navigation.
- Theory Of Mind : (constructing a representation of ‘another’ as opposed to self) . Thus this too involves a shifting of focus from one agent to another with the concurrent risk that the new representation may not be true.
Note that all of the above involve or are about persons or entities with agencies and their beliefs/ memories / imaginations and how they are distinct from the actual reality. This is important as the neural evidence would pertain to only this class of imaginations and would not generalize to imagining events not involving agency, for example imagining a unicorn.
In what sense might a meta-representational capacity be essential for mind-reading? Let’s define mind-reading as the ability to put yourself in someone else’s shoes, to imagine the other person’s thoughts and feelings.iv Leslie’s deeply interesting argument is that when you mind-read, you again need to quarantine your primary representations. Here’s how his argument goes. Just as your mental picture of a fish has ‘truth relations’ to a real fish in the outside world, so a belief, or a sentence, has truth relations to real events in the outside world. Thus, ‘John is having an affair with his colleague’ is a primary representation of a state of affairs, and is true if John is indeed having an affair with his colleague. But when we mind-read, we again take the primary representation (step one), copy it so that it becomes a second-order representation (step two), and can then add a prefix (step three) that completely changes its truth relations with the outside world.
Thus, we can take the primary representation ‘John is having an affair with his colleague’ (step one). We can copy it to produce an identical version ‘John is having an affair with his colleague’, except this version is tagged as being a copy or a second-order representation (step two). Finally, we can add a prefix such as ‘Mary believes that’ to the second-order representation to end up with ‘Mary believes that “John is having an affair with his colleague” ’ (step three).
Such second-order representations have unique logical properties, an insight that Leslie borrowed from the standard views in philosophy of mind. They have, to use the jargon, referential opacity. ‘I pretend that “this tea-cup is hot” ’ is true if I pretend this, irrespective of whether the tea-cup really is hot. ‘Mary believes that “John is having an affair with his colleague” ’ is true if Mary believes it, irrespective of whether John really is having an affair. According to Leslie, and I think he is right, when we mind-read (just as when we use imagination), we employ such second-order representations. I can maintain my own knowledge base (John is not having an affair) whilst representing someone else’s different (possibly false) belief (Mary believes he is).
Thus, ToM has also been placed squarely in the category of tasks requiring Imagination, as we have defined it. Simon than contends that in Autism children lack this Imagination circuit or network and have deficts with ToM in particular and Imagination in general. Thus, as per this hypothesis they must also have problems imagining future autobiographical events, problems with episodic memory and problems with perspective taking approach to spatial navigation. All this still needs to be tested.
Let me now digress a little and point to data that suggests that the module we are talking about is specific to Imagination involving Agency and not for all second-order representations. When confronted with questions that do not require an agency , the autistic people perform as well on control tasks that require false representations in the mind.
To determine whether the poor performance of autistic children is due to a specific impairment in theory of mind, Leslie constructed a control task that very closely resembles the Sally-Ann task but does not rely on theory of mind. In the control task, the children watch an actor photograph a cat that is sitting on a chair. The cat then moves to a bed, and the subject is asked to predict what the photo will show. The control task is formally similar to the Sally-Ann task in that both tasks require children to infer the contents of a representation that does not reflect the current state of affairs. The photograph task and a standard FB task were given to normal 3 and 4-year-olds and mental-age-matched autistic adolescents. The autistic children performed slightly better than the normal 4-year-olds on the photograph task but worse than normal children on the standard FB task. The normal 3-year-olds failed both the FB task and the control task. The autistic children also outperformed normal children on another control task. In the second control task, the position of a cat was marked on a map. The cat then moved, and children were asked to predict the location of the mark on the map. The results indicate that autistic kids can meet the general problem solving demands of false belief tasks, but normally developing 3-year-olds cannot.
Leslie concludes that the three year olds have a difficulty with suppressing or inhibiting their own beliefs and desires (the primary representations) and selecting the second-order representations or beliefs of Sally. Thus his hypothesis is that their performance reflects a failure of inhibition or selection processing. this is clearly tied to the third ability we have identified of keeping two representations operate. They confuse between the two, and it is my contention that this is due to their inability to hold two representations of same objects in memory at the same time. Thus, three year olds also do not have episodic memory or the capacity to hold in memory the same object representations, but with different time coordinates.
Leslie also demonstrates that this deficit in inhibition, that is age dependent, is different from the deficit in Autistic children. I suspect the deficits in Autistic people are due to their propensity to view entities with agency too as objects and thus not having any beliefs , desires or emotions.
Now let me return to the Buckner and Carrol paper. It is an important paper that shows that we use the same brain areas for Remembering the past, imagining the future, ToM tasks and Navigation. Morover, the paper shows that this default network is nothing else but the default network in brain. It is to be remembered that the default network is the network active in absence of any stimulus and one feature of Agency dependent imagination we have seen earlier is that one should be able to form representations in absence of any stimuli. Also, we have already covered research that suggest that same brain areas are used for remembering the past and imagining the future.
Let me give you the abstract of the paper:
When thinking about the future or the upcoming actions of another person, we mentally project ourselves into that alternative situation. Accumulating data suggest that envisioning the future (prospection), remembering the past, conceiving the viewpoint of others (theory of mind) and possibly some forms of navigation reflect the workings of the same core brain network. These abilities emerge at a similar age and share a common functional anatomy that includes frontal and medial temporal systems that are traditionally associated with planning, episodic memory and default (passive) cognitive states. We speculate that these abilities, most often studied as distinct, rely on a common set of processes by which past experiences are used adaptively to imagine perspectives and events beyond those that emerge from the immediate environment.
I would request that the readers go back up a little and re-read the faculties required for imagination:
They involve second-order representation without stimulus (as in the activity in default network when no tasks are being carried. This spontaneous activity in the default network suggest that this is one region that can do its work without any input data.)
Distorting, changing , modifying the representation and moving them back and forth in time and space: I believe the frontal regions are involved in combining different stimuli, sequencing and planning them to archive novel combinations.
Keeping the false/ imagined/ other-people representations distinct from primary representations: I believe medial temporal lobe is crucial here. It is implicated in learning and memory and for keeping representations of past events (episodic memory). It thus has to keep the representations distinct, so that many memories may have the same constituent objects. Thus, the medial temporal lobe, I believe is mainly responsible for keeping the representations distinct.
It is interesting to note that the default network comprises of precisely these brain areas – the PFC and other frontal areas and the medial temporal lobe along with temporal-parietal junctions implicated in ToM. Also the fronto-polar region is implicated in the shifting of perspectives from self to other, from now to then etc and may be the most affected in Autism..
Functions that shift the perspective from the immediate environment to another vantage point create an interesting challenge for the brain. We must keep track of these shifts, otherwise our perceptions would blur together. Decety and Gre´zes note that ‘reality and imagination are not confused’. A computational model of how such a process might be structured is far from being defined, but it will probably require a form of regulation by which perception of the current world is suppressed while simulation of possible alternatives are constructed, followed by a return to perception of the present. Povinelli considered this issue from a developmental perspective and noted that coordination of internal perspectives ‘paves the way for the child to sustain not simply one current representation of the self but also to organize previous, current, and future representations under the temporally extended, metaconcept of ‘‘me’’’
The Fronto-polar regions are suspected behind this ability and I suspect are the most affected in Autism.
A final set of findings suggests that the frontopolar cortex contributes to theory of mind.
Thus Autism stems from the ToM deficts in the fronto-polar regions, plus the inability to keep many simultaneous representations in mind/’memory’. I would also suspect that same region is involved in agency attribution.
What does this selective generalization mean? The combined observations suggest that the core network that supports remembering, prospection, theory of mind and related tasks is not shared by all tasks that require complex problem solving or imagination. Rather, the network seems to be specialized for, and actively engaged by, mental acts that require the projection of oneself into another time, place or perspective. Prospection and related forms of self-projection might enable mental simulations that involve the interactions of people, who have intentions and autonomous mental states, by projecting our own mental states into different vantage points, in an analogous manner to how one projects oneself into the past and future.
In the end they very wisely conclude:
In this article, we have considered the speculative possibility that a core brain network supports multiple forms of self-projection. Thinking about the future, episodic remembering, conceiving the perspective of others (theory of mind) and navigation engage this network, which suggests that they share similar reliance on internal modes of cognition and on brain systems that enable perception of alternative vantage points. Perhaps these abilities, traditionally considered as distinct, are best understood as part of a larger class of function that enables flexible forms of self-projection. By this view, self-projection relies closely on memory systems because past experience serves as the foundation on which alternative perspectives and conceived futures are built.
That brings us to my final conclusion. I believe this is further evidence for the different cultures of Schizophrenia and Autism. If Autistic have a deficit with this ToM/ Agency default network, we also know that in schizophrenics too the default network works abnormally. I presume it acts unusually in the opposite way to that in Autism- attributing more agency, involving more imagination and self-projection.
I was browsing through a blog post by Developing Intelligence and came across this link to a talk by Greenfield et al, regarding pretend play capabilities of Chimpanzees and Bonobos. In this, it is asserted that Chimpanzees and Bonobos are able to achieve level4 of pretend play, that is observed in Humans by themselves and if they are scaffolded or guided by Humans in their Zone of Proximal Development, they can also achieve the stage 5 (the highest stage achieved) . The levels were levels of pretend play as described by McCune and Agayoff (2002) and based on descriptions by Piaget (1951). No web searches by me could lead me to the definition of these levels on the web and I would be glad if any of the readers of this blog, who are familiar with these levels, could update me on this by posting in the comments.
However, I did come across some other levels or stages associated with pretend play and could link them up with my previous postings on moral, cognitive, perspective and language development.
To outline my position, I intend to show that pretend play or Symbolic play follows the same stages as involved in language acquisition and the analogy is true for both Language syntax as well as lexicon acquisition. Further, it may be the case, that pretend play stages precede corresponding language stages and are necessary for successful language acquisition in all stages.
First, I would like to distinguish between the form of pretend play and its contents. The form of pretend play may consist of different predicates
- An Agent that is pretending (or the Role (R))
- A pretentious or false act (this is the Pretense (P))
- A false representation of an object (this is the substituted object (O))
Thus, a pretend play P = R P O
The child may start initially start by forming a concept of pretenses as something that is not really true (stage I); start creating pretenses with real life objects e.g. using real life objects in pretentious acts (like pretended talking on an actual mobile) (stage II); gradually combine two of these (using banana as a mobile and pretending to talk on it) (stage III); gradually graduate to elaborate pretensions whereby not only objects stand for something else and actions stand for something else, but also the role assumed by the child may vary, and is usually that of adults (stage IV); and in later stages the roles , object-representations etc may even be novel and not something that the child has encountered in its usual socializing (stage V).
This staged manner is analogous in language acquisition to babbling (whereby one starts creating words), one word speech (whereby one starts using a word for representing a thing), two word speech (whereby one combines actions, nouns etc in two word phrases to create sentences) and finally telegraphic speech (too much bound by rules learned from observation of adults) and finally adult speech based on pragmatics.
More interesting is some stages described in “Multiple Perspectives on Play in Early Childhood Education” By Olivia N Saracho, Bernard Spodek for individual lexicons- like that for object substitution.
Elena Bugrimenko and Elena Sminova have proposed five stages in symbolic play (ages 18 to 30 months)
- Stage 1 : Children play only with realistic toys and show no interest in object substitution performed by adults
- Stage 2: Children automatically imitate adult-initiated object substitutions, but do not appear to understand that one object has been substituted for other.
- Stage 3: Children independently imitate object substitutions previously performed by an adult.
- Stage4: Children initiate their own object substitutions, but do not rename the objects with substitute names
- Stage 5: Children originate and rename
It is interesting to note that individual elements of a pretend play like object-substitution, themselves go through developmental stages.
Another interesting study mentioned in “Understanding Child Development: For Adults Who Work with Young Children” By Rosalind Charlesworth refers to the actual pretense act and how that pretense act becomes more complex as the child goes through different developmental stages. In the following example, the ‘pretended act of feeding/eating’ should be considered.
According to Nicolich(1977), toddlers develop through a sequence of stages in their play, as seen in the following example:
- Stage 1: Rudy picks up a spoon, looks at it, puts in his mouth, hangs it on the floor, and drops it.
- Stage2: Rudy picks up the spoon and pretends to eat.
- Stage 3: Rudy uses the spoon to feed a doll.
- Stage 4: Rudy mixes up some pretend food in a pan with the spoon. He uses the spoon to put some pretend food in a dish. He then proceeds to eat, using the same spoon.
- Stage 5: Rudy goes to the shelf. He takes a plate, cup, and saucer and carefully places them on the table. He returns to the shelf and gets a spoon, knife and fork with which he completes the place setting. His mother sits at the table. Rudy says. ‘Soup, mom’. He feeds her with the spoon.
It is interesting to observe that in the above examples, the child in stage 1 is developing his sensory-motor abilities to indulge in a pretend act of eating; in stage 2 he actually indulges in a pretend act that is directed towards himself. In stage 3, he directs the pretense act towards someone else ( a doll) , in stage 4 he goes through a sequence of activities and rituals as observed in a normal social context, in stage 5 he indulges in elaborate planning, setting up the stage and understands that other people can also pretend juts like him and directs the pretend act towards another human being.
To develop the staged theory of pretend play further, consider role-playing agent (that is the child indulging in pretense play). The discussion is based on the following stages (doc) available on the web. (italicized comments mine)
Stage I: Imitative Role Play: In this initial stage of play, children try to act, talk, and dress like people they know. Children use real objects as props. They depend on an element of reality in their play. For instance, a child may pick up a telephone and pretend to “talk on the phone like Mommy” or hold a doll and “feed the baby.” One starts developing a concept of a ‘pretended role’ but needs to ground that with the actual props that are used and this play is a solitary activity.
Stage II: Make-Believe Play: In the second stage, children’s play is enriched by their imaginations. Now less dependent on concrete props for role-playing, children may use a string as a firefighter’s hose, or an envelope may be Mommy’s briefcase. The ability to make-believe moves beyond the scope of real props or costumes. Children also learn to use their imaginations to invent actions and situations. Dramatic play is no longer confined to real-life events. At this stage, children often use such play to help them understand feelings or deal with fears and worries. Point to note that one has developed a concept of ‘pretend roles’ and does not need to depend on external props for achieving that role. The role-playing is still mostly a solitary activity.
Stage III: Socio-Dramatic Play: Socio-dramatic play emerges at the time children begin seeking the company of others. Socio-dramatic play includes elements of imitative play and make-believe play; however, it stands apart from the earlier stages in that it requires verbal interaction between two or more children. Because of its interactive nature, socio-dramatic play necessitates planning. One child chooses to be the teacher and the other the student; one child can be a firefighter and the other a would-be victim. Because of its more complex story lines, socio-dramatic play requires that children spend a significant amount of time in this type of play. This play, in my view, is characterized by role-play involving two persons. One knows what role one is supposed to play and what the other person has to play and one may even switch roles during the play. This marks the beginning of ‘social’ pretend play.
To the above stages I will add two of my own stages of role-playing:
Stage IV : Mythological/ Archetypal / adult role playing : Here the child may enact the different roles played by mythological or archetypal characters that are prevalent in his culture. He may one minute play Ravana, the next Rama, the next Laxmana, the next Jatauyu and the next Sita (all characters of Ramayana). Thus, he starts understanding that one may have different roles and pretenses at different times and a typical sequence of play would involve permuting between different roles in succession. One is exposed to not only the fact that different roles can be assumed sequentially, but also gets exposed to how it feels to act in that particular social role that is prevalent in one’s culture. One would normally imitate adult roles and also play with adults (mother) in this role-playing.
Stage V: Novel role-playing: Here the role-playing with peers becomes more important. Also one seeks novel roles like that of an Alien invader and uses the imagination to come up with novel pretend roles. One may pretend to be novel animals – an El-zebra – an elephant that has stripes and runs very fast. One may pretend not to be a ‘role’ like a doctor, but a ‘person’ like one’s best friend and say that I am Bill and act like Bill (for e.g. cuddling dolls like Bill does). Thus, one may move from ‘pretend roles’ to pretend persons’ and even go on the do mimicry using voice intonation, gait etc to pretend to be another person!! One has mastered the art of pretend role-playing.
I’ll briefly try to link this up with another post by Developing Intelligence relating symbol usage with Language development/evolution. Please read the post now, as I wont repeat the arguments made by David Premack here and assume that the reader has read them via the above link.
Premack tries to make an argument for uniqueness of existence of language in Humans due to some Symbol manipulation related abilities that we humans have over other apes. I’ll not go into the argument whether, and to what extent, these capabilities exist in Apes (I guess Premack is a sufficiently good authority on that), but will try to show how those symbolic abilities unique to humans, as outlined, are involved in the staged development of pretend play.
- Voluntary Control of Motor Behavior. Premack argues that because both vocalization and facial expression are largely involuntary in the chimpanzee, they are incapable of developing a symbol system like speech or sign language. This relates to the first stage of a pretend act development. Rudy because of the ability for voluntary control of hands can grasp and move the spoon to make a pretend act of eating.
- Imitation. Because chimpanzees can only imitate an actor’s actions on an object, but not the actions in the absence of the object that was acted upon, Premack suggests that language cannot evolve. This is the requirement for Stage 2 pretense act. Even when the object (food) is not there, Rudy can still act, as-if, the food is present and thus pretend to eat it.
- Teaching. Premack claims that teaching behaviors are strictly human, defining teaching as “reverse imitation” – in which a model actor observes and corrects an imitator. This may be required for third stage wherein Rudy may actually be ‘teaching’ the doll how to eat. Feeding the doll, gives Rudy an opportunity to indulge in reverse imitation and correction.
- Theory of Mind. Chimps can ascribe goals to others’ actions, but Premack suggests these attributions are limited in recursion (i.e., no “I think you thought he would have thought that.”) Premack states that because recursion is a necessary component of human language, and because all other animals lack recursion, they cannot possibly evolve human language. This may relate to both stage 4 and 5 wherein Rudy is able to sequence multiple pretensions (adding raw material, cooking, eating , serving) and thus also acquires the ability to sequence (or recurse or embed) multiple abstract symbolic representations. Rudy may also exhibit stage 5 awareness of ascribing the goal of ‘having food’ or ‘being hungry’ to Mom who would thus be willing to collaborate in the pretend play.
- Grammar. Not only do chimps use nonrecursive grammars, they also use only words that are grounded in sensory experience – according to Premack, all attempts have failed to train chimps to use words with meanings grounded in metaphor rather than sensory experience. This use of metaphorical symbolic representation may be related to the fact that in stage 5 Rudy can draw an analogy between the pretend act of feeding oneself and the pretend act of feeding the m0m. The original act of feeding self that was replaced by the pretended act of feeding self has been replaced and construed as analogous to feeding someone else.
- Intelligence. Here Premack suggests that the uniquely human characteristics of language are supported by human intelligence. Our capacity to flexibly recombine pieces of sensory experience supports language, while the relative lack of such flexibility in other animals precludes them from using human-language like symbol systems. For this we will have to go to stages 6, 7 and 8:-)
To sum up, there seem to be interesting parallels involved in all developmental stages, be that of Moral development, Language development or Symbolic Usage (Pretend Play) development and this tells us about some of the constraints, templates and guidelines under which development takes place.