Animal Cognition - July 2018

**Intuitive optics: What great apes**
infer from mirrors and shadows (Voelter & Call, 2018)

In a
series of experiments, researchers asked what kind of information great apes
can infer from mirrors and shadows in order to help discriminate appearance
from reality. In the first experiment, all ape species were able to locate food
using a mirror or a shadow. In a second experiment they compared the shadow
condition to a control condition where the experimenter placed a black rubber
object on the side where the food was slid, to mimic a shadow in a sense. This
was to see if the apes would perform the same using perceptually similar cues
for where the food was hidden. However, they performed at chance in this new
‘arbitrary’ (black rubber object) condition while maintaining above chance in
the shadow condition. Since the reward was always where the shadow or rubber
object was, this finding was a little surprising to me. Experiment 3 assessed
whether apes could extract depth information from a mirror. Subjects were able
to adjust their response and select the truly closer food item despite appearing
farther in the reflection. Experiment 4 manipulated angles of the mirror and
experiment 5 compared mirror-naïve chimpanzees to chimps that had scored above
chance on Experiments 1, 3, and 4. Before each trial subjects were shown either
two mirrors, where they could see their own reflections, or two pictures, one
of which looked like the reflection of the food. The food was always hidden
where they could see its reflection or where the picture of the reflection was.
Overall, experienced chimps performed better than naïve chimps in both the
mirror and picture demonstration conditions. Notably, they performed much
better than mirror-naïve chimps on the first trial of mirror demonstration
trials. There is a lot going on here, but I think I would have liked to see a
condition where they had to discriminate between an image and a mirror’s
reflection rather than just something against nothing – as most of these
conditions did.

**Spatial representation of magnitude**
in humans (*Homo sapiens*), western
lowland gorillas (*Gorilla gorilla gorilla*),
and American black bears (*Ursus*
americanus*) (Johnson-Ulrich & Vonk, 2018). '*

Here’s one
for the SNARC people. Subjects had to respond to either a smaller or larger
array of dots, and the arrays were either static or moving. All species showed
some evidence of a SNARC effect when looking at accuracy or response time.
However, for bears and gorillas, the evidence was pretty limited – some
individuals only showed an effect for accuracy or for response time, and only
for congruent trials. No SNARC in human subjects for reaction time, and only 2
SNARC effects based on accuracy. The effects were clearer once regression
slopes were standardized, with nearly all groups showing an effect, but
direction and strength of effect varied across subjects. The authors point out
that a lack of explicit instructions may have contributed to this and suggest
that his testing paradigm may not be the best for assessing the SNARC effect in
comparative research. In other words, for a phenomenon assumed present in
humans, only testing paradigms that produce robust results for humans should be
used to assess the phenomenon in nonhuman species.

**Neophobia does not account for**
**motoric self-regulation performance as measured during the detour-reaching**
cylinder task (Stow, Vernouillet, & Kelley, 2018)

Two
species of corvids were assessed for neophobic behaviors using novel
environment and novel object exploration paradigms. Then, a detour-reaching
cylinder task was used to examine motoric inhibitory control. The scores from
the two measures of neophobia (novel environment and novel object) did not
correlate with each other. These scores also did not explain individual
differences in cylinder task performance (neither did species or sex or their
interaction) – suggesting that neophobic responses do not relate to motoric
self-regulation in these species. This study was partially based off one that
did find performance in a detour task affected by novelty responses in domestic
chicks (Regolin et al, 1994: Perceptual and motivational aspects of detour
behavior in young chicks. *Anim Behav 47,*
123-31.)

**Pigeons play the percentages:**
**computation of probability in a bird (Roberts, MacDonald, & Ha Lo, 2018)**

Another
probability paper for you guys. Here researchers tested pigeons in an operant
chamber with keys that reinforced at different probabilities. There was a
preference for a key that reinforced 75% of the time over a key that reinforced
25% of the time, even when the keys yielded the same overall amount of
reinforcers. In experiment 3, when both keys provided 50% reinforcement pigeons
showed no preference, even though one key provided 3 times as many reinforcers.
The authors conclude that the pigeons are basing their choices on the
probabilities the keys will reinforce rather than on the total amount of reinforcers
they are receiving. Their choices are a little unexpected (selecting the 75%
key even more than would be expected if subjects were probability matching),
but towards the end the authors break down the overall rate of reinforcement
for each key across the 3 experiments, showing a faster overall rate for the
75% key in experiments 1 and 2 and equal rates of reinforcement for the keys in
experiment 3. So maybe the pigeons are basing their selection on the rate of
reinforcement? Curious to see what you guys think of this one!

**Where’s the cookie? The ability of**
**monkeys to track object transpositions (Majecka & Pietraszewski, 2018)**

Object
permanence in 10 species of monkeys (19 total individuals). Experimenters
placed a reward under 1 of 2 cups that always started in the same positions,
but then were moved around according to several variants. Monkeys did well, getting
the most right when the cup movements were less complex.  Comparing to similar studies, monkeys did
better than dogs but worse than apes.

Other
articles that might interest some:

**Young macaques (*Macaca fascicularis*) preferentially bias**
**attention towards closer, older, and better tool users (Tan, Hemelrijk,**
Malaivijitnond, & Gumert, 2018)

Young
macaques interact with adults to obtain food, but watch tool users perhaps in
order to learn and maximize feeding opportunities.

**Spatio-temporal organization during**
**group formation in rats (Weiss, Levi, Segev, Simbirsky, & Eilam, 2018)**

**Relative salience of syllable structure**
**and syllable order in zebra finch song (Lawson, Fishbein, Prior, Ball, &**
Dooling, 2018)

**Testing domain general learning in**
**an Australian lizard (Qi, Noble, Fu, & Whiting, 2018)**

Lizards
that performed well on a spatial task performed the same as lizards that did
not perform well on a spatial task in an instrumental and a discrimination task.
Overall, the lizards did well on all tasks. Authors suggest focusing on
individual differences may be a better way of classifying learning abilities
than an overall domain general or domain specific.