Stimulus elicited behaviour

• Stimulus-elicited behaviour


  Behaviour produced as an involuntary and relatively immediate consequence of sensory stimulation: the behaviour is a reaction (or response) to a stimulus
• Stimulus-elicited behaviour is involuntary, many internally initiated behaviours are voluntary (in people)
• Types of motor behaviours


  • Stimulus-elicited behaviours
  • Internally initiated behaviours
  • Spontaneous behaviours
• Reflex


  A stimulus-elicited behaviour
• Autonomic reflex


  One mediated by the autonomic nervous system (ANS)
• Many reflexes are mediated by the ANS, which controls smooth muscles, cardiac muscle and glands
• Reflexes that involve skeletal muscles (skeletomotor reflexes) are not autonomic
• Examples of reflexes


  • Muscle stretch reflexes
  • Withdrawal reflexes
  • Eye-blink reflex
  • Vestibular-ocular reflex
  • Wiping/scratching reflexes
  • Startle reflex
  • Orienting reflex
• Proximal stimulus (or stimulation)


  Physical energy or force (electromagnetic, mechanical, acoustic, chemical) that impinges on sensory receptors and evokes a change in their membrane potential
• Distal stimulus


  A perceived/perceptible object, structure, substance, state of affairs or event in the environment/body. These are sources or causes of proximal stimulation (&/or of its features and patterns)
• A reflex is a stimulus-elicited behaviour elicited by proximal stimulation
• If the behavioural response is elicited by a distal stimulus, then the behaviour is not a reflex: it is some other kind of stimulus-elicited behaviour
• Egg retrieval behaviour in ground nesting birds


  • The graylag goose
• Egg retrieval behaviour is not a reflex as the animal must identify the egg, not simply respond to proximal stimulation
• Releasing mode of elicitation


  The stimulus triggers the response in a discrete fashion. The response is 'stored' beforehand and the stimulus releases it.
• Driving mode of elicitation


  The stimulus drives the response in a continuous fashion: neural activation evoked by the stimulus is transformed into efferent signals to the muscles.
• Stimulus driven responses vary with stimulus characteristics - e.g., a strong or intense stimulus evokes a large response
• Stimulus-released responses are independent of the intensity of the stimulus: the response is the same 'size' regardless of the strength of the eliciting stimulus
• Characteristics of stimulus driven reflex responses


  • Duration: if the eliciting stimulus persists, the response persists
  • Amplitude/vigour: if the eliciting stimulus is intense/strong, the response is larger/more vigorous
  • Variation: if the eliciting stimulus strength increases and decreases, response vigor increases and decreases
• Releasing mode of elicitation is appropriate when you want the size of the response be independent of the stimulus strength
• The orienting reflex involves turning the head, eyes and sometimes the body so that you are 'oriented' towards the source of eliciting stimulation, and you want the turn to depend upon the location of the stimulation, not on its strength