insect-level intelligence
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Insect-level intelligence
Information for performing tasks
Learning about home – a routine for acquisition
Exploration and the return from newly discovered sites
Learning routes – scaffolding
Multiple routes and memory retrieval
Representation of space: routes not maps
Behaviours generally evolve within a specific ecological niche and the strategies and underlying neural systems may only operate effectively in that niche.
Predator avoidance: categorisation using simple features
Zeil and Hemmi, 2006
Crabs live on a flat surface where all objects above the horizon are classified as predators
Zeil and Hemmi 2006
Unexpected sophistication:
Crabs at first run to their burrow whenever they spot movement above the horizon.
But, if objects are presented repeatedly, their escape attempts habituate, unless the object is a dummy bird.
(Hemmi and Zeil)
Behaviour is also guided by complex information
Burrows are a valued resource and fiddler crabs keep their burrow under constant surveillance. They return rapidly to it if an intruder threatens to take it over.
Zeil and Hemmi 2006
A crab starts to rush home when an intruder comes within a set distance of the burrow. How does it gauge this distance when the hole is invisible?
Crab can know the distance of the intruder from retinal elevation and of the burrow from path integration. These egocentric measures must be combined to give the allocentric distance of intruder from burrow.
Ants, social bees and wasps collect food for their nest. Individuals stick to one or few foraging sites and learn fixed routes between these sites and their nest.
Cataglyphis bicolor
Collett, Dillman, Giger and Wehner, 1992
Homeward routes of Cataglyphis bicolor
Behavioural routines for learning
A bumblebee leaving its nest for the first time may be gone for an hour and then return to a small nest hole with a load of pollen.
On departure. the bee performs an elaborate flight that helps acquire landmark information that can guide its return.
The structure of such learning flights reveal efficient strategies for acquiring visual information.
Collett (1995)
10 cm
Learning flight of Vespula vulgaris leaving feeder
10 cm
Two learning flights from one wasp
Moments during six of the wasp’s flights when it faces the feeder (+)
Return flights to feeder
Note consistent body orientation when is close to the goal
Body orientation in learning and return flights
Wasp 1
Wasp 2
Learning flight(when facing feeder)
Return flight(when close to feeder)
Wehner, Meier, Zollikofer (2004)
Route learning in Cataglyphis starts with exploration.
Successive foraging trips of an unsuccessful ant
White numbers show successful trips
Wehner, Meier, Zollikofer (2004)
A luckier ant
Wehner 1982, 1990
Path integration encodes the coordinates of an ant’s current position relative to the nest so providing it with the information to go straight home.
Ants encode the path integration coordinates of a newly discovered feeding site into long term memory and so can return directly to the site through path integration.
Collett, Collett, Wehner, 1999
Such straight routes due to path integration are
modulated by innate visuo-motor responses to objects.
Collett, Collett and Wehner (2000)
Route modulation by barrier
Graham and Collett (2002)
Graham and Collett (2002)
Graham, Fauria, Collett (2003)
Route modulation by beacon
Scaffolding allows route to be acquired simultaneously along the whole sequence.
It also means little chance of learning the wrong thing, so no danger in acquiring routes fast.
Why does the ant bother to learn routes if it can reach its destination through path integration?
Route memories are linked to motivational state
Food-ward and homeward routes overlap
Wehner (2003)
Formica rufa
Harris, Hempel de Ibarra, Graham and Collett (2006)
Harris, Hempel de Ibarra, Graham and Collett (2006)
Wehner et al. (2006)
Food-ward route not recognised by ant in homeward motivational state
Memories primed by panoramic context
Collett, Fauria, Baron, Dale 1997
Honeybees in a 2 compartment maze in one place
Collett, Baron, Sellen,1996
Spatial representation
Ants use visual landmarks in a procedural rather than a map-like way.
They are attracted towards places defined by landmarks or they associate motor commands with landmarks.
But landmarks are not labelled with positional coordinates.
Independence of PI and landmarks: PI coordinates are not reset by encountering familiar landmarks
Collett et al. 2003
Routes are independent of PI state: repeated homeward routes (red and black) do not differ from normal trajectories (grey).
Kohler and Wehner 2005
But home vector changes. After 1st repetition of homeward route there is no home vector. After 2nd repetition, home vector points away from nest.
Andell and Wehner, 2005
In mammals robust and flexible navigation is ensured by combining path integration and visual information.
Separating the two strategies also gives robustness, one strategy can take over when the other fails, and errors in one strategy do not contaminate the operation of the other.
A possible hallmark of insect intelligence is that it comprises smart, but specific and independent modules.
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