visually guided behaviours Flashcards
What is the concept of “active vision” in animals?
Active vision refers to the manipulation of the viewpoint by repositioning or reorienting the eyes to:
1. Explore the environment.
2. Obtain improved sensory information.
why is active vision important in animal behaviour
- Active vision is closely integrated with the animal’s own movements and behavior, helping guide tasks like predation or evasion.
- information inferred from visual images due to active vision, allows useful information which is used to guide animal behaviour tasks like landing and avoiding obstacles
What is the main question of the lecture on visually guided behaviors?
how animals use information acquired through active vision for a range of behaviors, such as predation, evasion, or landing.
How does active vision guide an animal’s behavior?
By stabilizing gaze and gathering environmental visual information, animals can perform behaviors like locating food, avoiding predators, and navigating their surroundings.
what do vision fields show
- show how birds eyes are oriented
- show binocular overlap
- show blind area
what are 2 features important in a bird’s visual field
- visual field show binocular overlap
- blind areas
What is binocular overlap, and why is it important in birds?
- Binocular overlap is the area where both eyes’ fields intersect.
- In birds, it mainly helps them see their bill tips for tool use or manipulation, for foraging
what is blind area and why is it important
- area where birds cannot see due to eye positioning
- insights into holocene and evolutionary envrionments
Why do ducks have an upward-oriented visual field?
- Ducks’ eyes are oriented upward to detect aerial predators while swimming, resulting in a blind spot below their head.
How does the Cattle Egret’s visual field differ, and why?
- It’s adapted for ground feeding with a forward-looking field, creating a blind spot behind the head. This suits its foraging strategy on land.
What is the significance of New Caledonian crows having a wide binocular overlap?
- their wide binocular overlap correlated with their fine tool use
- Their larger overlap correlates with advanced tool use,
- allowing more focus on bill for precise bill manipulation for extracting
How does human binocular vision differ from that of birds?
- Humans primarily rely on binocular overlap for stereopsis (depth perception),
- whereas many birds’ binocular overlap is more of a byproduct, from wider vision field in each eye to guide their bill or tools.
what is stereopsis
Stereopsis is the ability to perceive depth and see in three dimensions.
It’s a vital part of binocular vision, which occurs because each eye sees a slightly different image
Why are birds with large overhead blind sectors prone to power line collisions?
- Their visual fields evolved and are adapted for their natural habitats in the holocene
- leaving them blind to structures like power lines above (their blind areas are poorly adapted for overhead power lines)
- This mismatch causes more collisions in human-made environments (anthropocene)
- understanding bird navigation can prevent this
What role do visual interneurons play in bird flight?
- They detect visual motion cues.
- The arrangement of these interneurons is driven by flight behavior, aiding navigation and movement in different species.
- visual interneurons are arranged differently across species, and have different sensitivities which are tuned to the type of flight behaviour of specific species
Why are zebra finches and pigeons more sensitive to forward motion?
- They primarily fly straight, so their interneurons are tuned to better detect forward optic flow,
- helping them gauge speed and distance in a forward trajectory.
Hummingbirds & Motion Sensitivity
- Hummingbirds have interneurons responsive to motion in all directions,
- enabling them to hover and fly backward or forward efficiently.
Why is understanding birds’ visual fields and neural organization important?
It helps in designing environments and conservation measures (like marking power lines) to reduce collisions and supports insights into how vision drives behavior.
What is “optic flow”?
It is the pattern of apparent motion in the visual field caused by an animal’s movement, providing crucial information about self-motion, direction, and distance.
* Using both translational and rotational optic flow and the informational it provides, it can help birds and insects guide their flight behaviour
How do insects like flies process optic flow?
- Flies have about 13 widefield optic flow interneurons called LPTCs in the lobula plate,
- each tuned to respond to specific motion types (rotational, translational),
- helping more precise guide of flight behaviors.
What are lobula plate tangential cells (LPTCs)?
- They are specialized neurons in flies that act as matched filters,
- each detecting a frequently experienced motion pattern, enabling precise flight control.
- the specialised neurons are wired to detect most frequent/most experienced optic flows
How do flies use horizontal system neurons (HS) for flight?
- Flies have 3 HS neurons in the LBTC responsive to horizontal visual motion.
- For example, HSE responds strongly to optic flows during flight between saccades (during the fixation period)
- helping flies estimate distance on each side to stay centered.
how does HSE neurons help flies stay centred during flight
- during the fixation period of saccade + fixate, the HSE neurons detects optic flows
- By comparing right and left HSE neurons, flies are able to estimate relative distance to background on each side of animal (due to translational optic flow)
- This estimate of distance on right and left side allows insects to balance to remain centred
Example of Tunnel Navigation in Honeybees
- Honeybees balance translational optic flow from each side of a tunnel to remain in the center.
- experiments which induce asymmetry in translatiopnal optic cue on one side, bees shift closer to one wall, showing how translational optic flow cues guide navigation.
how do orchid bees navigate flying through forests
- they dont use simple optic flow based centering to navigate flying through their habitat
- they use brightness cues
Why do orchid bees rely on brightness cues rather than simple centering?
- They navigate cluttered forest environments where balancing optic flow alone is insufficient
- Bright areas indicate safe pathways such as gaps or sky, helping them maneuver more flexibly around obstacles.
what cues do honeybees use for landing
- looming cues
what are looming cues
- When an object approaches, its image on the retina expands. This expansion is a visual “looming” cue.
- The rate of expansion is directly related to how quickly the object appears to be approaching.
How do honeybees use looming cues for landing?
- They maintain a constant rate of visual field expansion to gauge landing speed.
- Expanding patterns indicate they are quickly approaching the landing target, indicating the bee is at a fast landing speed, this makes them land more slowly and cautiously
- contracting patterns suggest the target is receding, and is a further landing target. Indicating bees are currently at a slow landing speed, this prompts them to faster landings
What is collision avoidance in Drosophila based on?
- Drosophila detects lateral image expansion (looming cues from translational optic flow) on one side,
- triggering an asymmetric wingbeat response that steers them away from a potential collision.
How do hummingbirds center themselves differently from bees?
- Hummingbirds receive optic flow from all directions but rely on feature-based cues,
- they prefer flying towards narrower stripes.
- and they fly away from wider vertical stripes
- This helps them avoid large objects like tree trunks in natural habitats.
Why might hummingbirds avoid broad vertical stripes?
- Broad stripes likely represent large tree trunks or obstacles,
- so they steer away, demonstrating an adaptation for cluttered forest environments.
how does vision guide behaviour
Vision is not just for detection; it guides complex tasks like foraging, tool use, collision avoidance, and landing by combining visual fields, neural processing, and optic flow cues.
What is the key idea behind active vision and behavior?
- Animals shape their visual field/image (e.g., gaze stabilization, flight maneuvers), which allows them to infer useful information from vision
- and complete tasks like hunting, evasion, and navigation.
How do visual field anatomy and ecology relate in birds?
Binocular overlaps and blind areas evolved for specific needs—like predator avoidance or foraging in holocene—making some species vulnerable to modern hazards (e.g., power lines).
Why is neural tuning to optic flow so precise?
Many species, from flies to birds, have specialized neurons for the types of motion they experience most, ensuring efficient flight control and obstacle avoidance based on how frequent an optic motion is from past experience
Simple Cues for Complex Tasks
Brightness contrasts, looming, and optic flow combine to guide landing, collision avoidance, and navigation, showing how basic visual cues underpin important behaviors.
How far back do visually guided predatory behaviors date?
- They trace back to the Cambrian period, as shown by ancient arthropods (e.g., anomalocarids) with large compound eyes and raptorial appendages.
What evidence suggests visual predation is deeply conserved?
- Fossils show key optic lobe and neural circuit features in ancient arthropods show homology modern arthropods,
- indicating either deep homology or convergent evolution.
how do animals pursuit prey
- they use visual cues like proportional navigation to track and intercept prey
What is proportional navigation in target pursuit?
- It’s a pursuit algorithm where a predator turns at an angular velocity proportional to the rate of change in the line of sight to its target’s vector,
- enables interception.
how does a falcon use proptional navigation to intercept prey?
- falcons steer in the direction of the prey
- they then steer the direction of their attack trajectory by feeding back the angular rate of change of the target (relative to a fixed reference point)
- this allows adjustment of attack trajectory as the prey moves
- and allows interception of prey
Which animals use proportional navigation and how did it evolve?
- Falcons, predatory flies, robber flies, and many other taxa
- independently evolved similar line-of-sight feedback mechanisms for intercepting prey.
Visual System Feedback in target Pursuit using proportional navigation
- Eye and head stabilization provide information on target motion
- The angular rate of eye movement encodes how quickly and direction the target is moving away
- predator must turn proportional to that eye movement rate to intercept.
how do we build reliable mathematical model for attack trajectories
- mathematical models can easily model proportional navigation
- including physical limitations and other appropriate parameters of the model allow more realistic model which closely matches data
How do looming cues facilitate evasion?
- Expanding objects in the visual field signal a potential collision, or something getting closer
- prompting prey (e.g., fish) to perform evasive maneuvers like a rapid C-start away from the threat
experiment on reef fish for evasion
- reef fish in natural habitat exposed to artificial looming stimuli (a black dot getting larger)
- the fish respons to the optic looming cue and makes a C-start away from looming visual stimuli
- but the visual stimuli has to be expanding at specific rate and specific size and location because of matched filter
- neuron responses are matched to particular features of the stimuli which are threats to a fish (evolutionary adaptations)
- fish then make another trajectory which is also visually guided to th enearest shelter for safety
Why is matched-filter tuning important for evasion?
Prey neurons respond to looming stimuli of specific sizes and expansion rates, ensuring quick and accurate escape responses to real threats.
What is group vigilance in shoaling fish?
- Fish often form groups (forming schools and shoals)
- because in groups increase overall predator detection by sharing visual coverage (“many eyes”),
- even though some individuals in centre have partially blocked views, overall increases predator detection by group vigilance
- The group is more likely to see the predator and respond faster to an approaching predator as the group increases
What are the main rules of collective behavior?
- Attraction, repulsion, and alignment.
- These rules help fish maintain best group cohesion/arrangement, reduce predation risk, and coordinate escape responses.
Analogy to Auditory Systems
- Bats use “acoustic flow” (echolocation) much like optic flow, and both provide spatial information
- applying similar interception strategies and proportional navigation for hunting.
What are the core principles of visual sensorimotor systems?
- Many species use reference-based target tracking, matched-filter neurons, and proportional navigation pursuit or evasion algorithms, showing convergent evolution.
How do these principles apply to engineered systems?
Robotic sensorimotor designs often borrow from biological strategies—e.g., peripheral “morphological computation”—for efficient navigation and target tracking.
What broader strategies are linked by visual systems?
Target pursuit, collision avoidance, collective motion, and foraging all rely on similar visual cues, neural tuning, and feedback loops.
Key Lecture Takeaways
1) Vision is used actively in flight and predation.
2) Ancient visual mechanisms appear across taxa.
3) Simple pursuit algorithms by proportional navigation guide interception.
4) Group vigilance and collective behavior reduce predation risk.
5) Common sensorimotor principles emerge across species and modalities.
6) looming cues and brightness cues guide landing, prevent collision and evasion
How do physical and informational constraints shape these commonalities?
- Limited effective ways to interact with the environment from a physical and informational way
- drive convergent solutions (e.g., pursuit algorithms, looming cues) across diverse species, from arthropods to vertebrates.
