Lecture 6 - Signals and Information

Question 1

Sequence of elements

Answer 1

• Repetition: Single unit repeated more than once
• Diversity: A number of distinct units are present. Order is unimportant
• Combination: Set of units has different information from each unit individually. Order IS NOT important.
• Ordering: Set of units has different information from each unit individually. Order IS important.
• Overlapping: Information conveyed in the relationship between sequences of two or more individuals
• Timing: Timing between units (often between different individuals) conveys information

Question 2

Acoustic structure

Answer 2

Type of call (grunt vs scream)

Duration

F0 and formants contour and range

Energy quartiles

FM

AM

Question 3

Which kind of information can be encoded?

Answer 3

Functionally referential communication

Vocal expression of emotions

Question 4

Information transmitted by acoustic signal

Answer 4

Identity:
species, population, sex, individual

Characteristics/Quality: body size/weight, age, dominance

External events:
Functionally referential signals

Internal state:
Motivation, emotions

–> Static and dynamic information

Question 5

Identity information

Answer 5

Species
Population
Sex
Individual

–> Fixed throughout life
–> Strength (amount of information) depends on ecological constraints

Question 6

Individual identity

Answer 6

Can be more stereotyped - more variation among individuals than within individual

Or less stereotyped - less variation among individuals

Question 7

Parent-offspring recognition

Answer 7

• Offspring survival
• Reduces confusion over reproductive investment

Vocal recognition: long distance; large groups

Ecological constraints –> Direction (unidirectional/mutual) and timing of recognition

Question 8

Recognition in ungulates: Follower strategy (sheep, horse):
- Young follow the mother
- Flee, maternal and group defense
- Open habitats

Answer 8

Mutual vocal two-way recognition process

Question 9

Recognition in ungulates: Hider strategy (Deer, gazelle):
- First weeks of life: young lie concealed and silent in vegetation
- Mother visits them only for nursing
- Habitats providing cover

Answer 9

Unidirectional vocal recognition process

Question 10

Recognition in pinnipeds

Answer 10

‘Income’ breeders: regularly leave their pups to forage throughout lactation —> mutual vocal two-way recognition

‘Capital’ breeders: mostly fast throughout lactation —> unidirectional vocal recognition

Question 11

Characteristics/quality information

Answer 11

Body size/weight
Age
Dominance

–> To be ‘honest’ (reliable): Changes throughout life according to characteristics/quality

Question 12

Dominance information: Fallow deer

Answer 12

Males produce higher frequency groans (formants + F0) when older

More dominant males have lower frequency groans (formants + F0)

Question 13

Dominance information: humans

Answer 13

Low-frequency voice increases dominance ratings of both men and women (playbacks)

Men lower or raise their pitch according to perceived dominance

Men with low pitch = more attractive

Women with higher pitched voices = more attractive up to an optimal pitch (female voice > ca. 280 Hz less attractive)

Question 14

Morton’s motivational rules: Hostile interaction

Answer 14

Low frequency, loud and noisy (mimic large body size)

Question 15

Morton’s motivational rules: Fearful or appeasing interaction

Answer 15

High frequency, tonal (mimic small body size)

Question 16

Morton’s motivational rules: Friendly interaction

Answer 16

Soft, low-frequency, amplitude-modulated, rhythmic sounds (e.g. purr)

Question 17

Arousal and valence

Answer 17

More evidence for arousal (e.g. pain, hunger, predator) than valence

Across species:

Arousal –> Higher amplitude, higher and more variable frequencies

Valence –> shorter, lower and less variable F0

Question 18

Vervet alarm call system

Answer 18

Leopard –> run into trees

Eagle –> Look up

Snake –> Look down

Question 19

Male domestic chicken food calls

Answer 19

• Preferred food items (mealworms): higher call rate and shorter intervals
• Prob. females approaching higher for preferred food calls
• Hens look down only during playback of food calls (not during alarm and contact calls)

Question 20

Referent

Answer 20

Object or event external to the signaler

Question 21

Production specificity

Answer 21

Production needs to be context-specific (i.e. linked to the presence of a particular external referent)

Question 22

Perception specificity

Answer 22

Appropriate responses to the calls need to be stimulus-independent (i.e. in the absence of the referent)

Question 23

Proximate mechanisms unknown

Answer 23

–> Functionally referential

Question 24

Referentiality vs urgency

Answer 24

Functionally referential alarm calls (e.g. vervet monkeys)

Urgency-based alarm calls
(e.g. Sciuridae)

Combination (e.g. Meerkats)

Question 25

What is 'meaning' in animal communication

Answer 25

Literal meaning: code that maps signs onto the signified words --> referents Speaker or intended meaning: both the signaller and the receiver take each other's state of mind into account when communication

Question 26

What is 'intentional' in animal communication?

Answer 26

Social use Sensitivity to attentional state if recipient Manipulation of attentional state of recipient Audience checking and gaze alternation

Question 27

Intentional communication: social use

Answer 27

The signal is directed at a recipient. This can be asses at various levels: 1) presence/absence of audience effect: the signal is only produced in the presence of a recipient 2) Composition of audience: the signal is only produced in the presence of certain recipients (e.g. kin, dominants, friends) 3) Behavior of audience: signal production is contingent on the behavior of the recipient

Question 28

Intentional communication: sensitivity to attentional state of recipient

Answer 28

Visual signals are only produced in the field of view of recipients. If a signaler does not have a recipient's visual attention, tactile or auditory signals should be produced.

Question 29

Intentional communication: Manipulation of attentional state of recipient

Answer 29

Before a visual signal is produced, attention-getting behaviors are directed towards a recipient who is not visually attending to the signaler, or the signaler moves itself into the line of view of a recipient

Question 30

Intentional communication: Audience checking and gaze alteration

Answer 30

Signaler monitors the audience and visually orients towards the recipient before producing a signal. If a third entity is involved, gaze alternation may occur between recipients and this entity

Question 31

What is information?

Answer 31

Reduces uncertainty (e.g. about upcoming social interactions, events in the environment) Common view: Whether or not they were voluntary or intentional, animal signals provided listeners with information

Question 32

Information acquired by receiver depends on..

Answer 32

1. Properties of the signal --> informative value (reliable predictor?), referential specificity (range of eliciting stimuli), signal specificity (distinction from other signals) 2. Properties of the context

Question 33

Pragmatics

Answer 33

How context contributes to meaning Often (for humans), body cues (context), not facial expressions, discriminate between intense positive and negative emotions.

Question 34

Take-home message

Answer 34

Information can be encoded in: * Sequences of elements * Acoustic structure Vocalisations can contain information about: * Identity * Characteristics/Quality * Internal state * External events Meaning in animal communication: * Animal signals provide information to receivers → reduce uncertainty (e.g. about an event, environment) * Meaning = signal properties + context

Question 35

Information is encoded in…

Answer 35

Sequence of elements and acoustic structure