First published online December 15, 2004
Journal of Experimental Biology 208, 65-74 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01370
Weak and strong priming cues in bumblebee contextual learning
Kyran Dale,
Duane P. Harland
,
Adam Manning-Jones and
Thomas S. Collett*
School of Life Sciences, University of Sussex, Brighton BN1 9QG,
UK
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Fig. 1. Diagram of LCD screen and tunnel to feeder. E marks the entrance and F the
feeder. Solid and broken lines show the bee's path.
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Fig. 2. Bees used spatial contextual cues to differentiate between two feeding
sites. Top shows the arrangement of the apparatus with training and test
stimuli. In the left flight box, the bees' task is to discriminate a rewarded
(+) blue-black checkerboard from a non-rewarded (-) yellow-black checkerboard,
and in the right flight box to discriminate a uniform rewarded yellow panel
(+) from a blue one (-). In the absence of colour, yellow is always light grey
and blue is dark grey. Bottom shows the bees' performance in tests with a
choice between the reward stimuli from the two boxes. In this, and the
remaining figures, choices are plotted cumulatively (ordinate) against the
sequence of tests or trials for the indicated condition (abscissa), with the
choices pooled over the group of bees tested (three in this case). We plot the
total score, the number of correct choices and the number of wrong choices.
The top edge of the grey wedge shows the null hypothesis of random choice.
Bees prefer the blue-black checkerboard over the yellow panel in the left box
and reverse their preference in the right box.
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Fig. 3. Bees used a sequential priming cue to choose a rewarded stimulus that they
approached after a short delay. Top shows the arrangement of training and test
stimuli. Bees entered the priming set up at the arrow at the bottom of the
diagram. A yellow priming stimulus in a tunnel predicted that bees should
approach a rewarded (+) blue-black checkerboard rather than a non-rewarded (-)
yellow-black checkerboard, and a blue priming stimulus in the same tunnel
predicted that a uniform yellow panel was rewarded and that a uniform blue
panel was unrewarded. The diagram shows baffles in front of the tunnel. Bottom
shows the results of the tests. When bees were trained with a priming tunnel
without baffles in front, their performance showed no influence of the priming
cues. Six bees trained with no baffles showed no preference for the blue-black
checkerboard, when the tunnel was yellow, or for the uniform yellow panel,
when the tunnel was blue. Seven bees trained with frontal baffles added to the
tunnel were influenced by the priming cues. They preferred the blue-black
checkerboard when the priming cue was yellow and the uniform yellow panel when
the priming cue was blue.
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Fig. 4. Bees failed to use a sequential priming cue to switch their choice of
colour. Top shows the arrangement of training stimuli. A yellow priming
stimulus in a tunnel with frontal baffles indicated that bees should approach
a yellow rather than a blue panel for a reward (+). A blue priming stimulus
indicated that the blue panel was rewarded (+) and the yellow panel unrewarded
(-). Bottom: seven bees failed to perform the task when trained for 180
trials. The group developed a slight preference for the yellow panel.
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Fig. 5. Bees trained in a two-step experiment failed to use a sequential priming
cue to switch their choice of colour. Top: in the first step of the
experiment, the two screens were placed in opposite corners of the arena with
their centres 210 cm apart, providing a different positional cue for each
screen. A group of four bees then learnt to approach the rewarded blue panel
in the left corner and the rewarded yellow panel in the right corner
significantly more often than the unrewarded panel. Bottom: the two screens
were moved close together with their centres 60 cm apart. One bee had ceased
foraging during the first stage of the experiment. The remaining three bees
failed to choose correctly and their performance did not recover over a
further 60 trials. They exhibited a slight preference for the blue panel,
whether the priming cue was blue or yellow.
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Fig. 6. Diagram of the priming compartment.
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Fig. 7. Bees failed to use the colour and position of the exit hole in a priming
compartment to select the colour of a rewarded stimulus. Top shows the
training arrangement. The bees' task is to approach the blue panel after
passing through the blue exit hole and the yellow panel after passing through
the yellow exit hole. Blue- and yellow-rewarded stimuli frequently switched
sides. Bottom shows the performance of a group of six bees when passing
through the blue exit hole on the left (with which training began) or the
yellow exit hole on the right. Over a training period of 79 trials, bees
failed to learn to pick the rewarded yellow screen after passing through the
yellow exit hole. Bees developed a blue preference that was independent of the
exit hole through which they left the priming compartment.
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Fig. 8. Bees failed to use a coloured exit hole to select a rewarded stimulus that
was in a fixed location. Top shows the training arrangement. The blue and
yellow exit holes from the priming compartment led to a further compartment
from which the bees entered the flight arena via a centrally placed exit
tunnel. The bees' task was to approach the rewarded blue screen when the blue
exit hole was open and to approach the yellow screen when the yellow exit hole
was open. Bottom shows the performance of a group of six bees during training.
At the start of training, the exit tunnel was 24 cm long. When, after 41
trials, it was clear that the bees had acquired the task, the exit tunnel was
extended to 42 cm. Performance then broke down and did not recover over a
further 55 trials, as shown by the correct and incorrect choice lines which
run parallel to or converge upon the random choice line. The vertical lines
through the graphs mark when the tunnel was extended.
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© The Company of Biologists Ltd 2005
