Tinbergen s four questions for investigating behavior Mechanism Ontogeny Function Evolution Topic for today
Socio-cognitive abilities of dogs mainstream research direction is bottom-up It starts with a comparative question: Do dogs have the capacity of, such as the humans/apes? e. g. Following visual cues Learning from demonstrators Attribute false beliefs to others, etc. Studies on vocal behavior however are usually based on observations of commonly occuring phenomena, similarly to some other examples, like Attachment behavior, empathy, guilt etc. Vocal behavior of dogs provides a unique chance for ethologists to study natural dog behavior and its possible functions, as well as an exciting opportunity for building theories about the course of evolution during the domestication process
Describing the abundance of canine vocalizations Early, but throughout efforts (Cohen and Fox, 1976) Recurrent problems with naming the categories Between-language correspondance A new (acoustics-based) categorization would be necessary Are there dog-specific vocalizations? * *= woof woof in Hungarian
Compared to the closest relative (wolves Feddersen- Petersen, 2000) Different acoustics? (yes and no) Different contexts? (yes and no) WHY? Function? Evolution? Answer may shed light to events during domestication
Cohen & Fox, 1976 meow grunt Greeting F WD WC D Play initiation whine yelp scream yip howl coo growl cough bark click tooth snap D F C WD R WD - D - - F - - D D - - - - - - D - WK FD Submission F - WC D Defense - - WC D D K W CD CF W - - - - - - - - - - W - WC DF Threat - - - - - - - - WC DF Contact seeking nf DF n, D W C nw nc D WC DF WC DF WD F WC D WC DF F WC D F C - F - - D - - - - - pant Pain/ distress n - n, D WC F Loneliness - - n, D WC Group vocalization - - n, D W C nw nc D n, D W C F D - - W C D - - C W C D - - - D - D - - - F - - D - - - - W C D - - - - -
Predominantly dog-specific occurrence Abundant (easy to experience/collect) Large acoustic variability, and different from the wolves bark
The role of barks in dog-dog communication Early non-communicative theories Hypertrophy Excitement Neoteny Cohen and Fox, 1976 Coppinger and Feinstein, 1991 Mobbing theory (Lord et al., 2009) Acoustic similarities (bark = mobbing signal) Bark contexts are only partly overlapping with the opportunity to mob (unlike barking alone, joint action with owner etc.)
Back to the basics reliable acoustic features are needed for possible categories of information Identity, affective state, context, etc. Early analyses (few parameters, related to mostly context and affective state) Yin, 2002; Pongrácz et al., 2005) Machine learning approaches (many parameters, also about identity, sex, age of the dog) (Molnár et al., 2008; Larrañaga et al., 2013 Anim. Cogn.) The acoustic basis is given for information transfer between dogs
Habituation-dishabituation paradigm Dogs show evidence of hearing the difference IDENTITY, CONTEXT Maros et al., 2008 Appl. Anim. Behav. Sci. Molnár et al., 2009 Behav. Proc. BUT the circumstances were far from being realistic What about the natural behavior?
The effects of context (affective state) and identity were tested Territorial ( stranger ) barks elicit strong reaction Distress ( alone ) barks do not Familiarity of the caller also counts PARTICULAR types of barks elicit appropriate response from the receiver dog OTHER barks ( alone ) elicit no response These latter are new compared to the wolf barks If they are communicative signals, who is the AUDIENCE? Pongrácz et al., 2014 Appl. Anim. Behav. Sci.
Chemical With little to no relevance for humans Visual Dogs understand a variety of human visual cues (Lakatos et al., 2009) Humans have to learn the body language of dogs (sometimes difficult) Misunderstanding can be fatal (small children / aggressive face expressions of dogs Meints et al.. 2010) Humans understand humanized visual cues, like gaze alternation (Miklósi et al., 2000) Acoustic Dogs are usually very vocal, but do we understand them???
Selection pressure alone is not an explanation it obviously did not work in the case of chemical and most of the visual signals Universal channel for (even interspecific) communication? Two main explanatory hypotheses Evolution structural-motivational (Morton, 1977) Mechanism source-filter (Taylor and Reby, 2010)
General approach playback studies with large amount of standardized sound recordings (from Mudi dogs) CONTEXTS Stranger at the gate Schutzhund training Left alone Before walk Asking for ball Play Tasks for the participants Contextual recognition Rating of EMOTIONS Aggressiveness, Fear, Despair, Happiness, Playfulness
recognized situations (% + SE) Adults with different amount of experience with dogs High overall success rate of context recognition No effect of experience (Pongrácz et al., 2005 J. Comp. Psychol.) 50 45 40 35 30 25 20 15 10 5 0 ***: P<0.001 *** *** *** chance level=16.7% Mudi-owners Dog-owners Non-owners
Sighted and sightless adults (visual experience varies) High overall success rate of context recognition No effect of sightedness (Molnár et al., 2010 Q. J. Exp. Psychol.) correctly categorized situations (%) 45 40 35 30 25 20 15 10 5 *** *** *** chance level: 17% 0 Sightless from birth Sightless with visual experiment Sighted
Children with different extent of dog-experience Only three contexts, success rate mostly above chance level No effect of experience, general effect of age (Pongrácz et al., 2011 Appl. Anim. Behav. Sci.) correctly categorized situation (%+SE 100 90 80 70 60 50 40 30 20 10 0 * NS * *** *** *** *** *** 6 years old 8 years old 10 years old adults dog yes dog no
recognized situations (% + SE) 70 60 50 40 30 20 10 0 a ac bc ac bc c What could be the reason? Experience had only minimal effect Overall recognition rate is well above chance level Strong effect of contextchance recognition accuracy level=16.7% Stranger Schutzh. Walk Alone Ball Play Pongrácz et al., 2005 J. Comp. Psychol.
Repeated study on Hungarian and Portuguese samples. Pongrácz et al., 2006 Silva et al., submitted
Affective state of dogs in particular contexts was rated rather uniformly across the sample stranger, Schutzhund alone play These contexts were easier to recognize contextually as well Emotional assessment Contextual recognition (unconscious) (conscious)
Wolf-like ancestor Barks encode Aggression (defensive/offensive) Other affective states are being encoded by Howling Growls Whining, etc. Dogs Barks encode Aggression (defensive/offensive) Fear Frustration General excitement (?) Happiness / positive affective state What kind of selective pressure? Other types of vocalization remain intact, or become more rare (e.g. howling)
Human environment is of crucial importance Protection (i.e. passive tolerance) against the negative consequences of being loud (both the predators and shortage of prey) Preference for particular functions of barking (alarm, hunting, herding) Some forms of barks were retained (aggression) Some new forms turned to be useful (fear/separation) Some new forms were tolerated (playfulness) But see the new challenge! Nuisance barks
Theory of communicative relevance of auditory nuisance Particular signal-structures evolved for intense attention eliciting Baby cries (artificial version: siren) Natural response: intervention Dog barks do the same When intervention is impossible STRESS ANNOYANCE
High pitched barks are the most annoying Attention eliciting (baby cry, cat meow, sirens) No habituation Works, because of the NEW FUNCTION of barks Typical to dogs in trouble, separation Fast, harsh, deep barks are very annoying Aggressive vocalizations Original Works, function because of barks of the OLD similarity FUNCTION to wolves of barks Fight, flee, or intervene
Growls apparently no new function in the human environment Agonistic interactions Play Commonly encountered in dog-dog and dog-human interactions Testing of the information content of growls Step 1: intraspecific relations Step 2: dog-human communication
Playful vs. two types of agonistic growls Test situation matches with only one of the contexts
Dogs gave up only when a food guarding growl was played back Discrimination between agonistic and playful growls? Discrimination between two types of agonistic growls? Recognition of the food guarding growls? functional referentiality? 12 11 10 9 8 7 6 5 4 3 2 1 0 9 1 2 2 3 7 5 4 3 FG TS PL Type of growl playback leave eat take Faragó et al., 2010, Animal Behaviour
Human version of the aforementioned study Choose the correct context Rate the affective state Each context was recognized above chance level Emotional rating congruent with context Food guarding growls were the most aggressive for HUMANS Maybe for dogs, too? (Faragó et al., subm.)
Play growl Formant dispersion of play and food guarding growls from the same dog show interesting difference Formant dispersion connected to the size of the vocal apparatus indirectly to body size Do dogs manipulate the indexical information about themselves? 1150 1100 1050 1000 950 Food guarding growl Formant dispersion A A B FG TS PL
Faragó et al., 2010, PLoS ONE Bálint et al., 2013, Appl. Anim. Behav. Sci. Food-guarding growls Dogs look at the matching size DOG picture + sound playback Playful growls Dogs look at the bigger size DOG picture
The honesty of agonistic growls may originate from the close-distance circumstances of these vocalizations, where cheating would be difficult due to the instant visual reference Exaggerated size information encoded in play-growls may serve to sustain playful context due to the obvious discrepancy between the acoustic and visual information What about indexical signaling towards humans? Taylor et al. (2008) found in play-back studies that humans are sensitive to the size-component of dog growls Would dogs use honest signals in an agonistic encounter also towards HUMANS?
Threatening stranger experiment Various human participants of small and large body size Male Female Multi-parameter acoustic analysis of the elicited growls
Dog growls with lower fundamental frequency and lower formant dispersion at MEN Experience counts, the effect is the strongest if the dogs lived in MIXED-GENDER families First time evidence was found that dogs modify vocal indexical information as a function of different AGONISTIC encounters Bálint, Faragó, Miklósi, Pongrácz (2016) in press Anim. Cogn.
Tonal sounds moan Atonal sounds whine growl yelp snarl woof whimper bark Frustration, anxiousness Warning, defense Play Fear, pain
Repetitiveness grows Recruiting effect; Long distance communication Tonal barks High pitched barks Non-aggressive inner states encoded Hypothesized receivers: HUMANS Long distance non-aggressive communication
Growls convey an abundance of information to other DOGS Growls are also understandable for HUMANS inner state? context (indexical features) body size Growls were found suitable for dynamic apparent size communication Voluntary control??? Effect on the receiver??? Learning???
Evolution Did breed-selection affect vocal behavior? Function What type of information do particular types of vocalizations convey to humans and dogs? Ontogeny How does the social environment affect the emergence of particular vocalization types? Mechanism Are there specific acoustic fingerprints of conditions such as separation-related disorder? (see the lecture of Faragó on Wednesday morning)