Roma, 15 gennaio 2010 1

Perception and actionPerception and actionA philosophical approachA philosophical approach

Sandro NanniniSandro NanniniUniversità di SienaUniversità di Siena

Dipartimento di Filosofia e Scienze SocialiDipartimento di Filosofia e Scienze Sociali

La La morte di Socratemorte di Socrate

L. David

2

Human beings and machines:Human beings and machines:Naturalising the mindNaturalising the mind

D. Dennett – D. Dennett – E il cervello è a sua volta E il cervello è a sua volta un’immensa macchina per molti versi un’immensa macchina per molti versi simile al computer […]simile al computer […]

E. Carli – E. Carli – Crede allora che sarebbe Crede allora che sarebbe possibile “amare” una macchina?possibile “amare” una macchina?

D. Dennett – D. Dennett – Quanto all’ipotesi di Quanto all’ipotesi di amare una macchina, devo dire che se amare una macchina, devo dire che se tale macchina fosse Michelle Pfeiffer tale macchina fosse Michelle Pfeiffer non vedo perché non potrei amarla.non vedo perché non potrei amarla.

((Cervelli che parlano, Cervelli che parlano, Mondadori, Mondadori, 1997, pp. 75-76)1997, pp. 75-76)

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Perception and sensory-motor coordinationPerception and sensory-motor coordination

• Animals acquired the Animals acquired the ability to perceive some ability to perceive some features of the external features of the external world and of their own world and of their own body in order to execute body in order to execute movements apt to movements apt to increase the probability to increase the probability to survivesurvive (e.g. by catching (e.g. by catching preys or avoiding preys or avoiding plunderers).plunderers).

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Perception and sensory-motor coordinationPerception and sensory-motor coordination

• Human senses and human Human senses and human sensorysensory--motor coordination motor coordination are the result of biological are the result of biological evolution.evolution.

BiologicalBiologicalevolutionevolution

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Perception and sensory-motor coordination:Perception and sensory-motor coordination:

• Perceptions can be Perceptions can be conscious or unconscious: conscious or unconscious: in both cases perceptions in both cases perceptions are are mental representationsmental representations of the internal and external of the internal and external world.world.

• Human beings construct a Human beings construct a representation of the representation of the external world in order to external world in order to move and act in it.move and act in it.

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The computational brainThe computational brain

• The brain acquires by means of The brain acquires by means of the senses a certain amount of the senses a certain amount of informationinformation about some about some regularities of the external world regularities of the external world as regards the distribution of as regards the distribution of matter and physical events in matter and physical events in space and time and space and time and changes the changes the formatformat of such information step of such information step by step until a pattern of motor by step until a pattern of motor neurons activity able to trigger a neurons activity able to trigger a right motor response is produced.right motor response is produced.

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Styles ofStyles of brain c brain computationomputationNo!!!No!!!

No representationsNo representations

May be!May be!

A Brooks’ robotA Brooks’ robot

UnlikelyUnlikely!!

Symbolic representationsSymbolic representations

Subsymbolic representationsSubsymbolic representations

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Frogs and fliesFrogs and flies

• A frog recognizes flies as food only A frog recognizes flies as food only if they are moving.if they are moving.

• We human beings instead We human beings instead

recognize flies as flies recognize flies as flies independently of their movements.independently of their movements.

• Therefore, the representation that Therefore, the representation that an animal has of its environment is an animal has of its environment is functional to the actions that it is functional to the actions that it is able to execute in that environment.able to execute in that environment.

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A reply to (3c): frogs and fliesA reply to (3c): frogs and flies

• It is not the case that we human It is not the case that we human beings see flies as they are, frogs beings see flies as they are, frogs instead see them as they appear to instead see them as they appear to them.them.

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The 1-eaters and the 2-eatersThe 1-eaters and the 2-eaters

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1000200000010000000200100000000001222200000010000000201000200000010000000200100000000001222200000010000000200100000000001222??????????????????????????????0100000000001222??????????????????????????????

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Which is the right representation? Which is the right representation?

It depends on what you eat!It depends on what you eat!

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Real world / phenomenal worldReal world / phenomenal world

• Mental representations are Mental representations are constructionsconstructions of the of the mind (=brain), not the mind (=brain), not the copiescopies of real objects. of real objects.

• There is similarity between the activity patterns of There is similarity between the activity patterns of hidden units in an artificial neural network and hidden units in an artificial neural network and mental representations: they are a mental representations: they are a representation representation (= a state space partition)(= a state space partition) of the input apt to get of the input apt to get the desired output.the desired output.

• Every species lives in its own Every species lives in its own phenomenalphenomenal world world adapted to a certain kind of interaction with the adapted to a certain kind of interaction with the realreal physical world. physical world.

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ConclusionConclusion• Perceptions can be naturalised only if the common Perceptions can be naturalised only if the common

sense concept of ‘perception’ is radically changed: sense concept of ‘perception’ is radically changed: perceptions are not perceptions are not copiescopies of real objects passively of real objects passively received from the external world but formats given to received from the external world but formats given to sensory inputs in order to sensory inputs in order to constructconstruct a stable and multi- a stable and multi-purpose model of reality that is able to control the purpose model of reality that is able to control the very flexible behaviour of human beings.very flexible behaviour of human beings.

• TheseThese perceptions can be functionally reduced and perceptions can be functionally reduced and therefore can be implemented by brain processes.therefore can be implemented by brain processes.

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Thank you for your attention!Thank you for your attention!