Clayton, Nicola S

Thom, James M

Frontiers in Psychology

English

PubMed

James M. Thom

Nicola S. Clayton

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GENERAL COMMENTARY
published: 11 February 2015
doi: 10.3389/fpsyg.2015.00144
Route-planning and the comparative study of
future-thinking
James M. Thom1* and Nicola S. Clayton2
1 Department of Philosophy, King’s College London, London, UK
2 Department of Psychology, University of Cambridge, Cambridge, UK
*Correspondence: james.thom@kcl.ac.uk
Edited by:
Aaron P. Blaisdell, University of California, Los Angeles, USA
Reviewed by:
Kazuo Fujita, Kyoto University, Japan
Keywords: mental time travel, navigation behavior, future thinking, chimpanzees, comparative cognition
A commentary on
Wild chimpanzees plan their breakfast
time, type, and location
by Janmaat, K. R., Polansky, L., Ban, S.
D., and Boesch, C. (2014). Proc. Natl.
Acad. Sci. U.S.A. 111, 16343–16348. doi:
10.1073/pnas.1407524111
Research into planning in non-human
animals has often focused on anticipa-
tion of future needs, with falsification
of the “Bischof-Köhler hypothesis” as the
gold standard. This hypothesis states that
non-human animals are unable to disso-
ciate from the present in order to con-
sider their future drives (Suddendorf and
Corballis, 1997). The Bischof-Köhler cri-
terion is intended as a test of constructive
future-thinking (or “mental time travel”),
in which the future is pre-experienced in
the mind’s eye (Atance and O’Neill, 2001).
Pre-experiencing future scenarios should,
the argument goes, allow the motivational
drives associated with those scenarios to
influence present behavior.
One recent study appears to offer com-
pelling evidence of “route-planning” in
chimpanzees (Janmaat et al., 2014). The
movements, nesting and feeding behav-
iors of five wild female chimpanzees were
monitored for 275 days. With other factors
(e.g., ambient temperature) controlled for,
the subjects responded to inter-specific
competition for breakfast fruit. The chim-
panzees departed toward the breakfast
trees earlier when the target fruit was
subject to greater competition (typically
smaller fruit). Furthermore, the chim-
panzees were also more likely to position
their nest sites the night before en route
to breakfast when breakfast was figs, which
were available on the trees for a shorter
time than other fruits. The authors argue
that this inferred route-planning is a
good example of future-thinking outside
humans.
However, it is not possible to com-
pletely rule out other explanations for
the observed behaviors. For example, the
authors dismiss time-place associations as
an explanation by excluding visits to a
breakfast tree after the first. This elimi-
nates a likely learning effect during the
course of the experiment, but it can-
not account for the accumulated experi-
ence of the adult subjects before the start
of the 275-day observation. Nonetheless,
this work offers intriguing questions for
future research. If, as the authors pro-
pose, chimpanzees balance predation risk
with competition for food when deciding
when to depart for breakfast, how flexibly
could they respond to new information? If
detained for a short time, would they alter
course for a tree less likely to be depleted
upon arrival?
Route-planning may also be fertile
ground for investigation of future-
thinking in other non-human animals.
Traveling the route to breakfast in one’s
mind ahead of time certainly seems
consistent with a lay definition of future-
thinking. Indeed, evidence of neural
activity corresponding to navigation of
future routes in rats (Pfeiffer and Foster,
2013) has been interpreted by some as
evidence of a degree of continuity of
future-thinking in mammals (Corballis,
2013), and as a potential constraint on the
evolution of future-thinking across other
clades (Thom and Clayton, 2014).
Route-planning and constructive
future-thinking also exhibit a shared
dependence on spatial processing
within the hippocampal formation.
Neuroimaging studies of constructive
future-thinking consistently identify hip-
pocampal activity (see Schacter et al., 2012
for a review), and patients with hippocam-
pal damage have difficulty imagining the
future (Klein et al., 2002). However, hip-
pocampal activity is also observed when
a subject constructs a scene with no tem-
poral placement at all (Hassabis et al.,
2007a). Similarly, some hippocampal
patients show impairments in imagination
of complex scenes but not simple objects,
with specific deficits in “spatial coherence”
(Hassabis et al., 2007b, but see Schacter
et al., 2012 for a summary of conflicting
cases). Maguire and colleagues therefore
argue that the hippocampus supports con-
structive future-thinking by laying down a
spatial framework for simulated scenes
(Hassabis and Maguire, 2007). Lesion
studies likewise identify the hippocam-
pus as important for navigation (Morris
et al., 1982). Importantly, activity in the
hippocampal formation is also implicated
in route-planning: when asked to mentally
navigate a route in a scanner, hippocam-
pal activity correlates with the distance
between the subject and the end of the
route, while activity in adjacent entorhinal
cortex corresponds to the Euclidian vector
between the subject and her goal (Howard
et al., 2014).
We believe that substantive evidence
of route-planning that is truly flexible
www.frontiersin.org February 2015 | Volume 6 | Article 144 | 1
Thom and Clayton Route-planning and the comparative study of future-thinking
should be considered as strongly sugges-
tive of a capacity for a certain type of
future-thinking. However, it is not clear
that such evidence would be sufficient
to refute the Bischof-Köhler hypothesis.
Can an intention to arrive at a destina-
tion before a certain time be considered
a “future need”? More generally, it seems
likely that any route-planning to reach
breakfast is motivated by current desire
for food. The Bischof-Köhler hypothesis
has previously been criticized as neither a
necessary (Raby and Clayton, 2009) nor
a sufficient (Cheke and Clayton, 2010)
criterion for constructive future-thinking.
Indeed, dissociation of present and future
needs is something that even humans are
not particularly good at, as evidenced by
systematic over-purchasing when shop-
ping while hungry (Nisbett and Kanouse,
1969).
In our view, the Bischof-Köhler
hypothesis is too narrow in its focus
on anticipation of future needs. It has
been used as a litmus test for future-
thinking, but future-thinking is not an
encapsulated, isolated ability. The Mental
Time Travel hypothesis identified sev-
eral important component processes that
overlap with other domains of cogni-
tion (Suddendorf and Corballis, 1997),
and more recent neuroimaging research
has emphasized a shared reliance on
hippocampal spatial processing in imagi-
nation and future-thinking (Hassabis and
Maguire, 2007). It is implausible that any
two species should be endowed with iden-
tical capacities for prospective cognition,
so any pass/fail litmus test will eventu-
ally prove to be of limited utility. With
deeper elucidation of the mechanisms
of human future-thinking, we have the
opportunity to search for evolutionary
continuity in associated and component
processes. To this list we should add
route-planning.
REFERENCES
Atance, C. M., and O’Neill, D. K. (2001). Episodic
future thinking. Trends Cogn. Sci. 5, 533–539. doi:
10.1016/S1364-6613(00)01804-0
Cheke, L. G., and Clayton, N. S. (2010). Mental time
travel in animals. Wiley Interdiscip. Rev. Cogn. Sci.
1, 915–930. doi: 10.1002/wcs.59
Corballis, M. C. (2013). Mental time travel: a case for
evolutionary continuity. Trends Cogn. Sci. 17, 5–6.
doi: 10.1016/j.tics.2012.10.009
Hassabis, D., Kumaran, D., and Maguire, E. A.
(2007a). Using imagination to understand the
neural basis of episodic memory. J. Neurosci.
27, 14365–14374. doi: 10.1523/JNEUROSCI.4549-
07.2007
Hassabis, D., Kumaran, D., Vann, S. D., and
Maguire, E. A. (2007b). Patients with hippocam-
pal amnesia cannot imagine new experiences.
Proc. Natl. Acad. Sci. U.S.A. 104, 1726–1731. doi:
10.1073/pnas.0610561104
Hassabis, D., and Maguire, E. A. (2007).
Deconstructing episodic memory
with construction. Trends Cogn. Sci.
11, 299–306. doi: 10.1016/j.tics.2007.
05.001
Howard, L. R., Javadi, A. H., Yu, Y., Mill, R.
D., Morrison, L. C., Knight, R., et al. (2014).
The Hippocampus and entorhinal cortex encode
the path and euclidean distances to goals dur-
ing navigation. Curr. Biol. 24, 1331–1340. doi:
10.1016/j.cub.2014.05.001
Janmaat, K. R., Polansky, L., Ban, S. D., and
Boesch, C. (2014). Wild chimpanzees plan
their breakfast time, type, and location. Proc.
Natl. Acad. Sci. U.S.A. 111, 16343–16348. doi:
10.1073/pnas.1407524111
Klein, S. B., Loftus, J., and Kihlstrom, J. F. (2002).
Memory and temporal experience: the effects
of episodic memory loss on an amnesic
patient’s ability to remember the past and
imagine the future. Soc. Cogn. 20, 353–379. doi:
10.1521/soco.20.5.353.21125
Morris, R., Garrud, P., Rawlins, J., and O’Keefe, J.
(1982). Place navigation impaired in rats with
hippocampal lesions. Nature 297, 681–683. doi:
10.1038/297681a0
Nisbett, R. E., and Kanouse, D. E. (1969). Obesity,
food deprivation, and supermarket shopping
behavior. J. Pers. Soc. Psychol. 12, 289–294. doi:
10.1037/h0027799
Pfeiffer, B. E., and Foster, D. J. (2013). Hippocampal
place-cell sequences depict future paths to
remembered goals. Nature 497, 74–79. doi:
10.1038/nature12112
Raby, C. R., and Clayton, N. S. (2009). Prospective
cognition in animals. Behav. Processes 80, 314–324.
doi: 10.1016/j.beproc.2008.12.005
Schacter, D. L., Addis, D. R., Hassabis, D., Martin,
V. C., Spreng, R. N., and Szpunar, K. K. (2012).
The future of memory: remembering, imagin-
ing, and the brain. Neuron 76, 677–694. doi:
10.1016/j.neuron.2012.11.001
Suddendorf, T., and Corballis, M. C. (1997). Mental
time travel and the evolution of the human mind.
Genet. Soc. Gen. Psychol. Monogr. 123, 133–167.
Thom, J. M., and Clayton, N. S. (2014). Continuity
in hippocampal function as a constraint on the
convergent evolution of episodic-like cognition.
Cosmology 18, 461–465.
Conflict of Interest Statement: The authors declare
that the research was conducted in the absence of any
commercial or financial relationships that could be
construed as a potential conflict of interest.
Received: 12 January 2015; accepted: 27 January 2015;
published online: 11 February 2015.
Citation: Thom JM and Clayton NS (2015) Route-
planning and the comparative study of future-thinking.
Front. Psychol. 6:144. doi: 10.3389/fpsyg.2015.00144
This article was submitted to Comparative Psychology, a
section of the journal Frontiers in Psychology.
Copyright © 2015 Thom and Clayton. This is an open-
access article distributed under the terms of the Creative
Commons Attribution License (CC BY). The use, dis-
tribution or reproduction in other forums is permitted,
provided the original author(s) or licensor are credited
and that the original publication in this journal is cited,
in accordance with accepted academic practice. No use,
distribution or reproduction is permitted which does not
comply with these terms.
Frontiers in Psychology | Comparative Psychology February 2015 | Volume 6 | Article 144 | 2


Route-planning and the comparative study of future-thinking

Crossref

Apollo (Cambridge)

GENERAL COMMENTARYpublished: 11 February 2015doi: 10.3389/fpsyg.2015.00144Route-planning and the comparative study offuture-thinkingJames M. Thom1* and Nicola S. Clayton21 Department of Philosophy, King’s College London, London, UK2 Department of Psychology, University of Cambridge, Cambridge, UK*Correspondence: james.thom@kcl.ac.ukEdited by:Aaron P. Blaisdell, University of California, Los Angeles, USAReviewed by:Kazuo Fujita, Kyoto University, JapanKeywords: mental time travel, navigation behavior, future thinking, chimpanzees, comparative cognitionA commentary onWild chimpanzees plan their breakfasttime, type, and locationby Janmaat, K. R., Polansky, L., Ban, S.D., and Boesch, C. (2014). Proc. Natl.Acad. Sci. U.S.A. 111, 16343–16348. doi:10.1073/pnas.1407524111Research into planning in non-humananimals has often focused on anticipa-tion of future needs, with falsificationof the “Bischof-Köhler hypothesis” as thegold standard. This hypothesis states thatnon-human animals are unable to disso-ciate from the present in order to con-sider their future drives (Suddendorf andCorballis, 1997). The Bischof-Köhler cri-terion is intended as a test of constructivefuture-thinking (or “mental time travel”),in which the future is pre-experienced inthe mind’s eye (Atance and O’Neill, 2001).Pre-experiencing future scenarios should,the argument goes, allow the motivationaldrives associated with those scenarios toinfluence present behavior.One recent study appears to offer com-pelling evidence of “route-planning” inchimpanzees (Janmaat et al., 2014). Themovements, nesting and feeding behav-iors of five wild female chimpanzees weremonitored for 275 days. With other factors(e.g., ambient temperature) controlled for,the subjects responded to inter-specificcompetition for breakfast fruit. The chim-panzees departed toward the breakfasttrees earlier when the target fruit wassubject to greater competition (typicallysmaller fruit). Furthermore, the chim-panzees were also more likely to positiontheir nest sites the night before en routeto breakfast when breakfast was figs, whichwere available on the trees for a shortertime than other fruits. The authors arguethat this inferred route-planning is agood example of future-thinking outsidehumans.However, it is not possible to com-pletely rule out other explanations forthe observed behaviors. For example, theauthors dismiss time-place associations asan explanation by excluding visits to abreakfast tree after the first. This elimi-nates a likely learning effect during thecourse of the experiment, but it can-not account for the accumulated experi-ence of the adult subjects before the startof the 275-day observation. Nonetheless,this work offers intriguing questions forfuture research. If, as the authors pro-pose, chimpanzees balance predation riskwith competition for food when decidingwhen to depart for breakfast, how flexiblycould they respond to new information? Ifdetained for a short time, would they altercourse for a tree less likely to be depletedupon arrival?Route-planning may also be fertileground for investigation of future-thinking in other non-human animals.Traveling the route to breakfast in one’smind ahead of time certainly seemsconsistent with a lay definition of future-thinking. Indeed, evidence of neuralactivity corresponding to navigation offuture routes in rats (Pfeiffer and Foster,2013) has been interpreted by some asevidence of a degree of continuity offuture-thinking in mammals (Corballis,2013), and as a potential constraint on theevolution of future-thinking across otherclades (Thom and Clayton, 2014).Route-planning and constructivefuture-thinking also exhibit a shareddependence on spatial processingwithin the hippocampal formation.Neuroimaging studies of constructivefuture-thinking consistently identify hip-pocampal activity (see Schacter et al., 2012for a review), and patients with hippocam-pal damage have difficulty imagining thefuture (Klein et al., 2002). However, hip-pocampal activity is also observed whena subject constructs a scene with no tem-poral placement at all (Hassabis et al.,2007a). Similarly, some hippocampalpatients show impairments in imaginationof complex scenes but not simple objects,with specific deficits in “spatial coherence”(Hassabis et al., 2007b, but see Schacteret al., 2012 for a summary of conflictingcases). Maguire and colleagues thereforeargue that the hippocampus supports con-structive future-thinking by laying down aspatial framework for simulated scenes(Hassabis and Maguire, 2007). Lesionstudies likewise identify the hippocam-pus as important for navigation (Morriset al., 1982). Importantly, activity in thehippocampal formation is also implicatedin route-planning: when asked to mentallynavigate a route in a scanner, hippocam-pal activity correlates with the distancebetween the subject and the end of theroute, while activity in adjacent entorhinalcortex corresponds to the Euclidian vectorbetween the subject and her goal (Howardet al., 2014).We believe that substantive evidenceof route-planning that is truly flexiblewww.frontiersin.org February 2015 | Volume 6 | Article 144 | 1Thom and Clayton Route-planning and the comparative study of future-thinkingshould be considered as strongly sugges-tive of a capacity for a certain type offuture-thinking. However, it is not clearthat such evidence would be sufficientto refute the Bischof-Köhler hypothesis.Can an intention to arrive at a destina-tion before a certain time be considereda “future need”? More generally, it seemslikely that any route-planning to reachbreakfast is motivated by current desirefor food. The Bischof-Köhler hypothesishas previously been criticized as neither anecessary (Raby and Clayton, 2009) nora sufficient (Cheke and Clayton, 2010)criterion for constructive future-thinking.Indeed, dissociation of present and futureneeds is something that even humans arenot particularly good at, as evidenced bysystematic over-purchasing when shop-ping while hungry (Nisbett and Kanouse,1969).In our view, the Bischof-Köhlerhypothesis is too narrow in its focuson anticipation of future needs. It hasbeen used as a litmus test for future-thinking, but future-thinking is not anencapsulated, isolated ability. The MentalTime Travel hypothesis identified sev-eral important component processes thatoverlap with other domains of cogni-tion (Suddendorf and Corballis, 1997),and more recent neuroimaging researchhas emphasized a shared reliance onhippocampal spatial processing in imagi-nation and future-thinking (Hassabis andMaguire, 2007). It is implausible that anytwo species should be endowed with iden-tical capacities for prospective cognition,so any pass/fail litmus test will eventu-ally prove to be of limited utility. Withdeeper elucidation of the mechanismsof human future-thinking, we have theopportunity to search for evolutionarycontinuity in associated and componentprocesses. To this list we should addroute-planning.REFERENCESAtance, C. M., and O’Neill, D. K. (2001). Episodicfuture thinking. Trends Cogn. Sci. 5, 533–539. doi:10.1016/S1364-6613(00)01804-0Cheke, L. G., and Clayton, N. S. (2010). Mental timetravel in animals. Wiley Interdiscip. Rev. Cogn. Sci.1, 915–930. doi: 10.1002/wcs.59Corballis, M. C. (2013). Mental time travel: a case forevolutionary continuity. Trends Cogn. Sci. 17, 5–6.doi: 10.1016/j.tics.2012.10.009Hassabis, D., Kumaran, D., and Maguire, E. A.(2007a). Using imagination to understand theneural basis of episodic memory. J. Neurosci.27, 14365–14374. doi: 10.1523/JNEUROSCI.4549-07.2007Hassabis, D., Kumaran, D., Vann, S. D., andMaguire, E. A. (2007b). Patients with hippocam-pal amnesia cannot imagine new experiences.Proc. Natl. Acad. Sci. U.S.A. 104, 1726–1731. doi:10.1073/pnas.0610561104Hassabis, D., and Maguire, E. A. (2007).Deconstructing episodic memorywith construction. Trends Cogn. Sci.11, 299–306. doi: 10.1016/j.tics.2007.05.001Howard, L. R., Javadi, A. H., Yu, Y., Mill, R.D., Morrison, L. C., Knight, R., et al. (2014).The Hippocampus and entorhinal cortex encodethe path and euclidean distances to goals dur-ing navigation. Curr. Biol. 24, 1331–1340. doi:10.1016/j.cub.2014.05.001Janmaat, K. R., Polansky, L., Ban, S. D., andBoesch, C. (2014). Wild chimpanzees plantheir breakfast time, type, and location. Proc.Natl. Acad. Sci. U.S.A. 111, 16343–16348. doi:10.1073/pnas.1407524111Klein, S. B., Loftus, J., and Kihlstrom, J. F. (2002).Memory and temporal experience: the effectsof episodic memory loss on an amnesicpatient’s ability to remember the past andimagine the future. Soc. Cogn. 20, 353–379. doi:10.1521/soco.20.5.353.21125Morris, R., Garrud, P., Rawlins, J., and O’Keefe, J.(1982). Place navigation impaired in rats withhippocampal lesions. Nature 297, 681–683. doi:10.1038/297681a0Nisbett, R. E., and Kanouse, D. E. (1969). Obesity,food deprivation, and supermarket shoppingbehavior. J. Pers. Soc. Psychol. 12, 289–294. doi:10.1037/h0027799Pfeiffer, B. E., and Foster, D. J. (2013). Hippocampalplace-cell sequences depict future paths toremembered goals. Nature 497, 74–79. doi:10.1038/nature12112Raby, C. R., and Clayton, N. S. (2009). Prospectivecognition in animals. Behav. Processes 80, 314–324.doi: 10.1016/j.beproc.2008.12.005Schacter, D. L., Addis, D. R., Hassabis, D., Martin,V. C., Spreng, R. N., and Szpunar, K. K. (2012).The future of memory: remembering, imagin-ing, and the brain. Neuron 76, 677–694. doi:10.1016/j.neuron.2012.11.001Suddendorf, T., and Corballis, M. C. (1997). Mentaltime travel and the evolution of the human mind.Genet. Soc. Gen. Psychol. Monogr. 123, 133–167.Thom, J. M., and Clayton, N. S. (2014). Continuityin hippocampal function as a constraint on theconvergent evolution of episodic-like cognition.Cosmology 18, 461–465.Conflict of Interest Statement: The authors declarethat the research was conducted in the absence of anycommercial or financial relationships that could beconstrued as a potential conflict of interest.Received: 12 January 2015; accepted: 27 January 2015;published online: 11 February 2015.Citation: Thom JM and Clayton NS (2015) Route-planning and the comparative study of future-thinking.Front. Psychol. 6:144. doi: 10.3389/fpsyg.2015.00144This article was submitted to Comparative Psychology, asection of the journal Frontiers in Psychology.Copyright © 2015 Thom and Clayton. This is an open-access article distributed under the terms of the CreativeCommons Attribution License (CC BY). The use, dis-tribution or reproduction in other forums is permitted,provided the original author(s) or licensor are creditedand that the original publication in this journal is cited,in accordance with accepted academic practice. No use,distribution or reproduction is permitted which does notcomply with these terms.Frontiers in Psychology | Comparative Psychology February 2015 | Volume 6 | Article 144 | 2

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