CATEGORIES OF STIMULI Releasing (or triggering) stimuli Orienting stimuli Priming stimuli Sign stimuli

CATEGORIES OF STIMULI Sign stimuli - species specific -release a reaction that is inherited not learned

Sign Stimuli 1. European robin Red breast releases aggressive behaviour in males

Complex Sign Stimuli Cues?? Herring Gull -chick pecks at parent’s beak to obtain regurgitated food Cues??

Two major cues are involved: 1. Yellow bill 2. Red spot on the mandible

Male Stickleback (Gasterosteus) Red Belly Red Belly + Head Down Posture

Innate Releasing Mechanisms SIGN STIMULUS receptor CNS IRM Match Motor pattern Generated Motor output No match No motor pattern generated

Fixed Action Pattern (FAP) Egg Rolling in a Greylag Goose

A series of FAP’s can be put into a sequence Female Male 1. Appears -heads up display 2. Zig-zag swim 3. Swims head up to male 4. Swim to nest 5. follows 6. Show nest 7. Enters nest 8. Tremble thrust 9. spawn

Should look like: In reality: 1 2 3 4 5 6 7 8 9

More Fixed Action Patterns

Modal Action Patterns

SUPERNORMAL STIMULI

SUPERNORMAL STIMULI Oystercatcher

Lorenz’s Hydraulic Model

Vacuum activity Time Court rolled up towel Court live female Court female model Court corner of cage

Displacement activity