Sensory Perception

Question 1

Vision

Answer 1

• canines eyes are more spherical compared to humans
• have visual streak that runs horizontally thru the back of the eye
• visual streak varied b/t breeds

Question 2

Retina

Answer 2

• has 2 photoreceptors: cones (color/detail) and rods (lighting/ movement)
• cones comprise 3% of photoreceptors
• no fovea
• enhanced visual acuity, binocular vision, and scanning

Question 3

Color Vision

Answer 3

• 1909, 1912: experiments done said dogs saw color poorly or not at all
• 1989: studies that dogs have dichromatic color (yellow and blue tones)

Question 4

Vision in Low Light

Answer 4

• pupils dilate to allow max light to enter
• rods are stimulated by low light
• tapetum lucidum ehances light
• tapetum nigrens: absorbs excessive scattered light

Question 5

Binocular Vision

Answer 5

• important for predators tracking prey movement
• overlap in visual fields, about 40-60 degrees of overlap
• peripheral vision 250 degrees in dogs

Question 6

Shape and Form Discrimination

Answer 6

• distinguishes moving shapes better
• distinguish individuals as part of group
• trouble reconciling unusual shapes

Question 7

Blindness

Answer 7

• causes of blindness is heredity and age
• can cause behavioral change
• deaf/blind dogs prone to aggression, dependece and attention seeking

Question 8

Part of the Ear

Answer 8

• external pinnae: gathers sound
• auditory canal: directs sound to eardrums
• tympanic membrane: eardrum
• cochlea: fluid filled and stimulates hair cells on basilar membrane

Question 9

Frequency and Range of Hearing

Answer 9

• Range is 15Hz to 60,000Hz, best at 4,000Hz

- can hear low freq. and ultrasound (like rodent patters)

Question 10

Auditory Localization

Answer 10

• advanced triangulation
• sound hits one ear slightly sooner
• w/ heading turning neuronal messages convey “picture” of location w/ sound

Question 11

Deafness

Answer 11

• congenital deafness: linked to white pigment
• 30% of Dalmatians are deaf
• exposure to loud noises

Question 12

Mechanics of Smell

Answer 12

• sample of air->nasal cavities->accumulates on mucous layer->picked up by odor sensitive cilia
• 250 olfactory neurons
• surface area of olfactory epithelium in dogs 20-200 sq. cm

Question 13

Smell and the Brain

Answer 13

• dogs have large olfactory bulb
• over 1000 kinds of olfactory receptor neurons
• largest family of genes known to exist

Question 14

Olfactory Acuity

Answer 14

• can discriminate particles 1 part per trillion
• ability varies on type of scent, best at butyric acid
• difficult to behaviorally test

Question 15

Biological Function of Smell

Answer 15

• prey location
• urine or scent marking and investigation
• fecal elimination doesn’t have same signaling effect
• sexual receptivity

Question 16

What roll on carrion of feces?

Answer 16

• camo or hunting technique

- scent as social cement/identification

Question 17

Detecting Human Odors

Answer 17

• can smell when we become afraid
• can detect seizures 15-45 prior
• can smell 6 week old fingerprints

Question 18

Tracking on Ground

Answer 18

-creates one path for dog to smell

Question 19

Tracking in Air

Answer 19

• creates scent cone

- advanced type of tracking

Question 20

Vomeronasal Organ

Answer 20

• behind front incisors and opens pouch containing neurons
• similar olfactory receptor neurons
• specialized to detect pheromones
• use tonguing, teeth chatter and licking the air

Question 21

Taste Buds

Answer 21

• salt, sugar and sour on 1/3 front of tongue
• umami: savory, meat, and cheese
• bitter is back of tongue
• taste present in neonates
• best response to sugar/sweet amino acids

Question 22

Dog Barks Affect on Humans

Answer 22

• low pitch and short intervals is aggression
• high pitch is desperate and fearful
• long intervals can be many things