Studies on Insect Cognition

Lecture 4

Psych 1090

Now, we’ve spent a few lectures discussing animal

cognition,

but concentrating on creatures mostly like apes, monkeys, and

parrots…

Creatures with either large brains or brains that are

organized somewhat like ours

but what about the insect world?

Until fairly recently, “insect cognition” was considered an

oxymoron

An ant brain has about 250,000 brain cells

For example, ant brains are among the largest per body

weight in insects…

mushroom shaped brain appendages have function similar to the gray-

matter of human brains.

But a human brain has 10,000 million brain cells

It has been estimated that an ant's brain may have the same

processing power as an old Macintosh II computer

Something that carries out a program, but can’t think on its

own

Behavior that seemed intelligent in creatures like

bees was dismissed as something rotely specified

immutable and inflexible

impervious to environmental influence

And, to some extent, a significant amount of insect

behavior is indeed like that…

If you put a ‘foreigner’ scent on a worker ant in some colonies,

the other workers attack, and nothing can be done to stop the

attack

But, as we will see, other aspects of insect behavior do seem to reflect some levels of intelligence….

learning, flexibility, adaptation to various

circumstances and, at least sometimes, at

primate-like levels

We’ll concentrate today on bees and spiders…

Not because ants—or a number of other insects—are

uninteresting

But just as representative critters

Jumping spiders are particularly intriguing

because they stalk, chase, and essentially hunt other critters…

a far cry from the view of a lump of protoplasm sitting on a web waiting for a meal to appear

In general, the spider we’ll discuss today, Portia,

Uses active mimicry to catch other spiders in their own

webs…As we’ll see, Portia lands on

webs and mimics the mating or prey behavior of the prey

spidermunching the occupant that

comes to investigate

But Portia is also able to adapt to other types of prey and their situation in a given

habitat…

In at least in one area where another type of prey spider

exists,

Portia has evolved a strategy to hunt it as well

The species, Euryattus, are also rather unusual, in

that

only the juveniles spin webs

Instead they inhabit curled up leaves that they suspend

Euryattus females also build suspension nests

that the males visit and on which they perform special

vibratory dances

The female is lured out and either mates or drives the male

away

And Portia capitalizes on this behavior

So to test exactly what Portia could do, the researchers gave it

a Euryattus female in her nest

a vacant Euryattus nest as one control

a choice between a juvenile Euryattus and a juvenile of another related species

a Euryattus juvenile in its web

The experimenters also used Portia of different ages, raised

in the lab w/o experience in nature

in order to see what could be changing with maturation w/o

experience

that way they could separate out learned behavior from what would just appear with age

They also tested male and female Portia

Conceivably, some difference could exist in the behavior based on

nutritional needs of egg-laying females

They also tested Portia from areas in which the Euryattus

spiders did not live

that comparison would allow them to determine if the

behavior had evolved only in the specific area in which it

was used

When given just the suspended Euryattus female in her nest

Only adult Portia females of the type that were sympatric with the Euryattus in the wild

succeeded in capturing and killing the Euryattus

And only that same subset of Portia in the lab

engaged in the specific “shuddering” behavior exhibited by the male

Euryatta

despite never having seen these males in the lab

If you looked only at final outcomes,

you’d figure that this behavior was just something that had

evolved for this particular situation

and that developed without any learned component

But you also have to look at the specific processes in which Portia engaged…..

Portia ‘waiting at the door’ after an initial failed attempt

Portia tracking whether it had been observed by Euryattus and freezing

Was Portia learning something from these

interactions?How much of the behavior

was fixed and how much was flexible?

Also, look at the defense strategies of Euryattus…

some of which succeeded

Note that Portia males and juvenile females attempted

the successful behavior patterns

But did not succeed and did not seem to ‘learn’ from

their failures

Tentatively, such data suggest some kind of

interplay between some innate, fixed

program and

some maturation of the ability to both learn, adapt,

and persevere

But let’s keep going….

What if you give Portia some empty Euryattus

nests?

Is Portia fooled in some way?

Will it perform the behavior, hoping that its prey will

eventually appear?

Well, yes, female Portias do go onto the leaves of the

empty nests and stick around…

So that tells us that Portia’s behavior is not triggered by,

say, the scent of a prey animal

But rather the observation of an appropriate nest

What about males and juveniles of the sympatric

Portia?

and what about allopatric Portia (those w/o Euryattus in

their natal area)?

Sympatric Portia adult females went and stayed more

frequently than other Portia species

Sympatric adult males acted similarly, tho’ females ‘waited’

more

So males either didn’t learn when driven off or didn’t care to wait

Note that earlier studies had already shown that males were less efficient

predators

But if they don’t need extra energy to lay eggs,

that might be evolutionarily fine

Allosympatric Portia pretty much did not respond

Suggesting that some genetic component had evolved only

in those Portia

that had this type of prey available

Of interest, however, was that the juvenile sympatric Portia

didn’t engage much in this behavior

was it simply because the behavior pattern had to

mature?

Or was it some “knowledge” that they

were just too small to take on the Euryatta

Euryatta females are about the same size,

and actually are predators in their own right….

Of course, one can imagine an evoltionary “just-so-story”

In which those Portia for which the behavior matured

too early

were themselves eaten and taken out of the gene pool…

So we really can’t argue for a level of conscious

decision on the part of the juveniles

And we can’t yet do any tests to separate out decision

versus genetic wiring

Note that if Portia faced off Euryattus that were not in

nests or webs

Portia succeeded when the Euryattus were small or

medium

But didn’t bother with a large one

Whether that was because the larger Euryattus could

more easily get away

and other prey was available

is unclear

Interestingly, too, is that Portia didn’t seem very interested in juvenile

Euryattus in their webs

Remember that Portia’s usual predatory technique is to mimic

a mate on a web

Somehow Portia recognizes the species on the web as

either

(a) too small to be worth pursuing

or

(b) juvenile and not interested in pursuing a potential mate on the

web

Note, too, that the Euryattus somehow did recognize Portia as

something predatory….

Portia is the only spider that will engage in these

particular behavior patterns…

other than conspecifics….

and tried to fight it off right away

Most other prey of Portia do not recognize it

Or at least not in time to escape from Portia once it is on their

webs…

Has Euryattus evolved some kind of “you-me” distinction?

The authors suggest some kind of evolutionary ‘arms race”

which means that each time one species evolves some technique

to its advantage,

the other species evolves some technique that overcomes this

advantage, ad infinitum

What is clear, however, is that even in what appear

to be set behavior patterns,

elements of decision and choice appear

arguing for at least some behavioral flexibility and cognition

In fact, Portia is quite the expert when it comes to

flexibility and at least some forms of learning…

And even if we don’t want to call the behavior advanced

cognition,

it’s quite impressive…

Again, the critical issue is that Portia has evolved

not to sit and wait for something to hit its web,

but to actively hunt other jumping spiders

And, what is more important,

is that Portia is a generalist…

a critter that is not specialized for just a few

types of prey

Portia engages in what appears to be classic trial-

and-error learning…

try a bunch of different behavior patterns

see which one seems to work the best in a given situation

and then concentrate on the winning strategy!

But what makes Portia unusual

is that it forgets or erases what worked the most recent time

so as to be able to start from scratch in a novel

situation

So, one might argue that failure to recognize

something familiar is a drawback

and evidence of stupidity rather than intelligence

but in the life of Portia, such is not the case

Because even if Portia finds the web of a similar prey

item,

The specific conditions are likely to differ….

and if Portia misreads the situation,

it might itself end up as dinner

In demonstrating this behavior, Jackson and

Wilcox again used Portia that were raised in the lab

Thus the individuals had no previous experience with the specific prey items used in

the experiments

The experimenter first put Portia on a three webs of the same species of prey spider

And showed that Portia adjusted its behavior to each of the different situations for

the same prey

Thus showing that it wasn’t something

specific about the web that triggered Portia’s

behaviorBut rather the actions of the

individual prey items

that led to the different types of Portia’s actions

Thus Portia was sending out a set of

signals…

determining what the prey was doing in response (which differed in each

case)

and adjusting behavior in response

And, yes, one might argue that there are just so many different

combinations and that these could be programmed…

But programming (hard-wiring) takes a lot of neural space

And the spiders don’t have that much; learning is more efficient

Next, the experimenters tagged prey spiders with

magnets so that the prey could be made to move on demand

They reinforced some random movement of Portia’s with the prey

movementAnd saw that Portia repeated

these randomly reinforced motions

Portia also could be ‘duped’ by fake movement if it could see a prey spider

And if a signal that was initially reinforced was no longer reinforced, Portia stopped

repeating it

And Portia could be duped into repeating a signal if it

saw, but not felt, a response by the prey spider

Such data suggested that Portia used visual and

vibratory cuesand could quickly alter use of cues

And, too, the experimenters choose only about five signals

out of the 100 or so that Portia could make

but repetitions were still limited to those that were

reinforced

Other data (Tarsitano and Jackson, 1997, Animal

Behaviour 53, 257-266) suggest that Portia has a

“cognitive map”

That is, if given an overview and then two indirect routes to

preyPortia more often chooses the

correct one

And we’ll talk a lot more about cognitive maps and what they

mean in bees in a bit

But remember that such ability will help Portia take a circuitous

route to its prey

which could be very important in not getting detected

Interestingly, when Portia of purportedly the same species but of different

habitat were compared…

One with high prey diversity and one with low prey diversity

and neither with any hunting experience

The Portia that came from the high prey diversity area used more trial-and-error

behavior

suggesting that what was maybe genetically fixed is the USE of

such behavior

and not a particular set of responses

Another study (Jackson, Carter, Tarsitano, 2001, Behaviour 138,

1215-1234 )

showed that Portia will use trial-and-error learning to

escape confinement

suggesting that such learning can be adapted to other tasks

But Portia’s “cleverness” doesn’t stop at trial-and-error

learning….

Portia also uses various background noises to mask its

stalking movements

Thus Portia has to be keenly aware of its environment

In the very basic experiments, Jackson and Wilcox put Portia onto the

web of its prey

then disturbed the web with either wind or a magnet that

mimicked the prey of the prey species (e.g., an insect caught

in the web)

Portia consistently moved closer to its prey during times of

disturbance

and there were no sex or age differences involved

Now, it could be that Portia just reacted to web disturbance

So the researchers tested whether Portia was

attending to what its own prey was doing during the

disturbance

Remember, Portia sometimes was on the web of a spider

that could attack and eat it as well….

First, they made sure that Portia would not respond to disturbance if the web was

empty of its own prey

or if it was on the web with something that didn’t need

stalking such as a moth

Interestingly, if disturbance was constant,

Portia was generally more successful, but sometimes gave

up

Possibly because the prey will sometimes leave the web

Basically, the wind interfered with the preys’

ability to detect Portia

but not Portia’s ability to detect the motion of the prey, likely

because Portia uses visual as well as vibratory cues

Further work by Jackson and his colleagues (Ethology 106, 2000, 595-615) showed that Portia will

also create its OWN smokescreen,

Setting up pulses of brief, strong rocking motions to confuse the

prey spider and hide its own movement

Sci AM

So, now that we know at least some spiders are

smart, what about bees?

The article we read was a bit old, but provided a really nice review of bee behavior

I’ll add some new stuff as well…

First, let’s state that a honeybee brain has only about 960000 neurons (I’m assuming this is what was meant in the

ant wrt brain cells)

So it’s got a lot more than the ant, but it’s also a lot bigger than

an ant

We’ll see that bees go beyond simple stimulus-response

associationsAnd that they seem to draw

inferences, at least with respect to what is ecologically valid to them…

Note that, like ants, they have mushroom bodies, which are sort of like human grey matter—areas

related to ‘intelligence’

So, these seem to be ideal critters in which

to examine insect cognition

Nevertheless, Gould doesn’t look at cognition quite the same way that I define it…

I want a subject not only to figure out the correct answer to a given

task

but to be able to do so for a wide variety of tasks

But bees seem to do fine on a number of different tasks related to their survival

And, as Gould states, there is definitely the need to access the capacities in terms of the

ecological niche

One of the big issues in bee behavior was how the bees

stored their representations…

And not only of a particular flower

but of the area in which they foraged

According to some data, animals recognize mirror images as identical to the

original…

Note that mirror images are NOT simple rotations of the

items…

Any arboreal animal had better understand rotation…

And, of course, the issue of what exactly one is asking the

animal is truly important

Remember the study that couldn’t understand why pigeons were sorting blue

and green things together?

So asking whether the bee can distinguish

from

is not the same as asking if it thinks they are quite similar

Is the animal ‘stupid’ because is ‘suffers’ from mirror-image ‘confusion’?

or is it ‘smart’ because it ‘understands’ the ‘relationship’

between mirror image ‘reversal’?

Depends on how the experimenter is defining the

issue!

When researchers found that bees couldn’t

understand 90 N rotations

the data didn’t make any sense…

Until they realized that they were using a vertical format specific to

the laboratory….

And that bees didn’t view flowers vertically, but did so horizontally

And, as Gould mentions, flowers have a specific type of

symmetry, as least as far as the bee sees

And, luckily, bees could easily be trained to win-stay

Obviously, researchers have to be very careful, the more different an animal is from a

human,

To design experiments that will reproduce the world of the

animal

rather than that of the human

Now, we obviously didn’t read about the symbolic bee

dances

And that is because I think that the topic is well-covered in a

number of other courses.. and we’ll see some video…

And, if needed, a nice review is in Griffin’s “Animal Minds”

And cognitive maps are just as controversial

Various papers argue that bees aren’t really using such maps

But rather some form of path integration, concerning the

distances and directions

But let’s see the issues starting w/ the material reviewed by Gould….

Let’s start with the idea of a cognitive map…

A mental representation that has various landmarks

So that you can decide the best way to get from one

point to another

Even if the route involves a detour or if you have never

taken that path before

So, the idea, is that if I know something about the

Harvard campus,

And the usual route between Wm James and the Oxford St garage is closed because of

construction

I can still figure out an efficient way to get to my car after class

The issue is

whether the bee can use

landmarks

Does the bee notice various aspects of its environment as

it searches for food…

And does it remember these various aspects over time?

And can it integrate these aspects over a fairly large

distance?

Although the idea makes a lot of sense for a human,

the question is how much sense it makes for a bee….

And Gould provides strong support for his thesis; I won’t go

over the details here

The real issue is how a brain that is so small, even

relative to the body weight,

stores this kind of information

and that is something that we have not yet completely

worked out

In fact, another set of researchers, Kirchner and Braun (Animal Behaviour,

1994, 48, 1437ff) argue that bees don’t have this map…

They interrupted the bees’ flight, put them in a wind tunnel turned

at a different angle

And when the bees were released, they didn’t act as

tho’ they had a map,

but rather flew and danced as tho’ the extra distance and the direction from the tunnel was

realHow do we deal with these data?

Well, one issue is that the wind tunnel was a real

experience for the bees….

It was open on top, but the sides were striped

The arrangement was like this:

Open to the sky gave

them the direction,

which was 90 N off the path

Conceivably, the experience was somehow part of the cognitive map that they

stored….And, as Gould states—and we

also know from homing pigeons—the bees will use whatever is

available

odor, landmarks, color, shapes, etc.

And they use them in whatever order is most likely

to help

Support for this hierarchy comes from other work by

Gould on mapsOnes that ‘fake’ the bees

And, conceivably, they update this information as needed…

Bees were

ferried out to

a station in the lake

X

When these bees returned and danced to tell the others of the

food source

They were ignored because the other bees “knew” that no

flowers grew in the middle of the lake

When the

scout bees were

put on a boat

near the shore

X

and then came back and danced about that

resource

they were followed because that more or less made sense according to what the bees

already knew

More recently, Sherman and Visscher (Nature, 2002, 419,

920-922) have shown that the bees really attend to the

dances when food is scarce…

food-location information in the dance is presumably important

when

Food sources are

hard to find

variable in richness

ephemeral

Such that any extra clues would be extremely useful

Remember, most of these studies,

even if carried out in open land

still use hives that are opened and shut and maintained by

researchers

So, we next look at a paper that puts the bees into a really

controlled experimental situation…

To see if it can understand ‘same’ and ‘different’

according to the rules we discussed last lecture

Well, even in the abstract, the authors admit

that what they will show is match-to-sample versus

nonmatch-to-sample

which we know isn’t really a concept of same/different

But how complex a concept can these bees learn?

Here the bees were, as were pigeons, trained to see A

And then asked to choose A or B

Then given C, with choice of C or D

The interesting thing was that bees got the match-

to-sample idea in only about 60 trials….

Which was an order of magnitude faster than the

pigeon…

Now, think of why…..

If you are a bee, colors and shapes are CRITICAL indicators of food….

Such is not really true for a pigeon

One problem with this paper is that we do not know how

many trials were needed for transfer

Even tho’ the

data are

good, we

need first trials

The bees were not, however, rewarded on the transfer trials

Which suggests that they probably were not learning anything about the novel

stimuli

Although the were ‘retrained’ after each set of transfer trials

And what seems weird to me was that the bees

had a 90 degree rotation on the vertical

lines….

Which other researchers had shown was really difficult

So, although the bees probably haven’t got a true

sense of same-different

They do, with their very tiny brains,

manage an ecologically relevant matching/nonmatching paradigm

and faster than pigeons

Recently, Dyer and his colleagues (J. Expt’l Biology,

2005, 208, 4709ff) argued that bees can recognize human

faces…

Something for which they would have absolutely no ecological predisposition…

He and his colleagues fastened a portrait above

each of four feeders

They used portraits of men's faces from a standard test used

to diagnose people with cognitive deficits

One picture was above two feeders with sugar

water

Others, a stylized cartoon and one real one, were above

feeders with quinine, which bees hate

Bees learned to go to the feeder with the one photo

The researchers then switched the photos around,

giving the bees the other pictures

Bees consistently chose that one picture EXCEPT

when the photos were upside down

Data which are consistent with the original work on bees having trouble with

vertical rotations…

Now, did the bees really learn to recognize a face?

or just a specific pattern?

Probably just the latter

Given that the expression never changed

Nor the ‘normal’ angle from which it was viewed

Nevertheless, it was a fairly complex form of

discrimination…

And that was really all the researchers wanted to

demonstrate

Now, remember that most of this material has been

on honeybees….

And it isn’t clear that bumblebees or stingless bees will respond quite the same

way…In fact, work on bumblebees

suggest slight brain differences compared to honeybees

although the researchers aren’t entirely clear about what these differences might mean (Brain, Behavior, and Evolution, 2005,

66, 50-61)

They do remind us that honeybee brains increase in size with age

and foraging experience…

which suggests some role for learning ….

But they also suggest that larger brains are needed for creatures that fill multiple

roles…

which honeybees do sequentially

In honey bees, workers perform different tasks depending on their age:

young workers care for the brood,

older ones guard the nest entrance

and the oldest workers forage

Thus the oldest ones are the ones that experience the

greatest variation in environment,

And probably need the greatest flexibility in their behavior

patterns

And only foraging honeybees have been tested….

So, with all that said…let’s look at some bee video…