Random Psych Questions =]

[d0minicz]

Explain why a combination of red and blue flashing lights on emergency vehicles enhances their visiblity in different light conditions.
need verification

and could please someone explain to me the STEPS involved in transduction .

thanks

[Glockmeister]

Explain why a combination of red and blue flashing lights on emergency vehicles enhances their visiblity in different light conditions.
need verification

I'm surprised no one responded yet (I was thinking Jessie might)

Very quickly (because I have to run to catch my bus), it is because the rods and cones are sensitive to different colours. Cones are more sensitive to red colour light and rods are more sensitive to blue light. The photorepector cells also work more effectively in different light conditions. Rods are more active in dim light conditions and Cones in bright light. Thus during the day, where there is bright light, the cones are being utilised and thus red light is easier to see. During the night, where it is not as bright, rods are being utilised and the blue lights are more easier to see.

and could please someone explain to me the STEPS involved in transduction .

I've been out of VCE land for a while, so I might make a mistake here, but transduction = the process where light energy is converted to chemical energy in the eye right?

If so, what happens is that light hits the back of the retina. When there is enough energy, an action potential is sent from the photoreceptors in the eye to the other cells involved in the transmission process (ganglion cells and the ilk).

[TrueLight]

ah i think some of your answer is wrong glockmiester............ but i will check later!!! and get back to you

[jess3254]

ah i think some of your answer is wrong glockmiester............ but i will check later!!! and get back to you

Which aspect? The first response seems correct to me. Cones (photoreceptors involved in colour/ day vision) are more sensitive to red because they respond better to longer wavelengths (and red has a long wavelength). In contrast, rods (photoreceptors involved in night vision) respond better to short wavelengths and thus would be more sensitive to blue/ violent colours. Hence why emergency vehicles possess both red and blue lights - so they are clearly visible both in the day and night. Here's a picture to demonstrate (I like pictures.)


Rods respond better                                                            Cones respond better


As for the second question, you don't need to know the specifics of the 'stages' of transduction. Basically, you just need to know is that transduction is the process by which light energy (electromagnetic energy) is converted into electrochemical energy (neural impulses). This occurs in the photoreceptors, located at the back of the retina. For interest sakes though:

1) Electromagnetic energy is detected by the photoreceptors (this really just describes 'reception'.)
2) When photosensitive pigments called photopigments, (which are located in both the rods and cones) are exposed to light, they 'bleach' or 'break down' into different chemicals.
3) The breaking down of photopigments causes the photoreceptors to lose their characteristic colour (hence why it is also called 'bleaching')
4) When photoreceptors 'bleach', the create graded potentials in the bipolar cells to which they are connected to, which may then fire.

[TrueLight]

yeah actually its probably right let me take some points from the lecturers notes

wavelength sensitivity:

in rods and cones the photopigment always consists of 11-cis-retinal combined to a protein opsin molecule. ALL rods have the same opsin molecule and the unit (opsin+11-cis-retinal) in rods is called rhodopsin. Cones have one of 3 different opsins and these opsins differ from that in rods. the opsin structure determine which wavelength of light the photopigment is most sensitive to. ALL rods have the same wavelength sensitivity curve. cones have 3 differnt curves depending on the opsin they have..... there is the short wavelgnth cone (blue light), medium wavelngth cone (green light) and a long wavelgnth cone (for red light) the rhodopsin has a optimal wavelngth of eh...i would say around 480-500nm can't tell precisely from the graph. ...
heres a graph of what im talking about!
http://mcdb.colorado.edu/courses/3280/images/photoreception/four-spectra.gif

so yeah i think thats why i was confused cause there is a 'blue' cone so i thought it was the cone....eh

rods are more sensitive to light than cones because they contain more photopigment and the light activated cascade is more efficient in rods than cones. this means that rods are almost non-functional in the daylight.. cones are less affected because they have efficient  light adaptation mechanism. therefore daylight viewing is better in cones than rods. night vision is dependant on rods. Rods respond slowly to and recover slowly to light stimulus. cones respond rapidly and recover rapidly, so rods are NOT good in detecting rapid changes in a stimulus but cones can.


ok...

cones are not DIRECTLY connected to retinal ganglion cells, they contact bipolar cells which contact RGC. two ways in which info. from cones can flow to RGC- direct pathway from receptors to bipolar cell to RGC and an indirect pathway where horizontal cells and amacrine cells are invovled....won't go into detail here...acuity comes from receptor field size and the amount of convergence.. acuity is highest at the fovea and descreases peripherally...



property                   foveal (cone) vision                    non foveal (rod) vision

directionality               axial only                                 any direction                             

wavelength sensitivity     colour vision                             non colour vision   

absolute sensitivity          low sensitivity, day vision            high sensitivity, night vision


type object detection        detects rapidly                                        detects slowly, detects only slowly
                                     detects rapidly moving/changing objects           moving/changing objects


acuity of vision                 high acuity, fine detail vision                           low acuity, detection vision

[d0minicz]

thanks for that ; is that all neccessary for vce knowledge ?

Another question:
Give an example of when a small child might have difficulty using shape constancy.
and
In your opinion, are visual constancies innate or learned? Give reasons.
thanks !

[jess3254]

thanks for that ; is that all neccessary for vce knowledge ?

Nah, it's not. As far as the VCE course goes, you're expected to know that:
Rods = respond better to short wavelengths
Cones = respond better to long wavelengths

Another question:
Give an example of when a small child might have difficulty using shape constancy.

Perceptual constancies, including shape constancy, rely on past experience or familiarity with an object. In other words, the more familiar we are with an object, the more readily we use size constancy. As a small child will have limited experience with a variety of objects, they will difficulty maintaining shape constancy. (Something along those lines.) For example, as a firetruck turns a corner, a small child may think it's changing its shape, rather than just changing its angle due to lack of familiarity with the fire truck.

In your opinion, are visual constancies innate or learned? Give reasons.
thanks !

Well, I'd say a combination of innate and learnt. Our ability to use constancies relies on familiarity or past experience with objects. Thus, it is to an extent learnt. However, studies have showed that when infants are presented with simple objects at different distances, they were able to demonstrate that one was further away from the other, suggesting that some basic elements of constancies may be innate (I'll try and find that study in a tick - this is just from memory.) I'll get back to you on that one though, I'll do some more research on it.

Perhaps someone with a university psychology text book + psychology database will be able to provide some more insight into the last question?

[d0minicz]

yay same opinion as me !
thanks alot jessie !

[Eriny]

According to http://science.jrank.org/pages/5094/Perception.html :

Perceptual constancy is one of the hallmarks of the field of perception, for it strongly indicates that visual perception involves more than the direct registration of the retinal image in the brain. Without perceptual constancy the world would be perceived as a booming blur of chaotic confusion in which the sizes, shapes, and colors of objects would be constantly shifting. Thus it can be seen that perceptual constancy serves an important adaptive function.

Despite constancy's great importance and prevalence across much of visual perception, there still no widely agreed upon explanation of it.There is, however, great agreement that constancy is based in part on the observer using appropriate contextual cues in the environment. For example, in size constancy it seems that in most instances we use estimates of detected distance based on various cues (for instance, haze, and a smoothing of textured surfaces such as grass are indicators of distance) to estimate an object's true size. And it seems that without cues enabling an accurate estimation of distance from an object, the perceived constancy of size ceases. For example, if one is extremely distant from objects without many intermediate visual cues enabling an accurate assessment of that distance, their perceived size would decrease. This is evident when looking at the world from a very high mountain top, or from a very tall building. From this distance, houses, cars, trees, and people below look very small, as if they were in miniature.

That doesn't really answer the question, sorry.

Additionally:

The perception of form can be said to result, in part, from characteristics of the nervous system, as well as learning and experience. Yet there is no single theory of form perception that can fully account for the ability to perceive form. Nor is there a general principle that can pull together the many different types of form perception.

In sum, binocular vision and environmental cues can account for many aspects of depth perception. In addition, based on research with animals and human infants too young to have had experience with depth perception, it appears that humans and various species of animals are born with some innate visual mechanism to perceive depth.

I doubt that you'd have to know any of that (still, pretty interesting though).

[Glockmeister]

Perceptual constancies, including shape constancy, rely on past experience or familiarity with an object. In other words, the more familiar we are with an object, the more readily we use size constancy. As a small child will have limited experience with a variety of objects, they will difficulty maintaining shape constancy. (Something along those lines.) For example, as a firetruck turns a corner, a small child may think it's changing its shape, rather than just changing its angle due to lack of familiarity with the fire truck.

In your opinion, are visual constancies innate or learned? Give reasons.
thanks !

Well, I'd say a combination of innate and learnt. Our ability to use constancies relies on familiarity or past experience with objects. Thus, it is to an extent learnt. However, studies have showed that when infants are presented with simple objects at different distances, they were able to demonstrate that one was further http://www.google.com.au/search?q=Dr+Max+Jory&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-GB:official&client=firefox-aaway from the other, suggesting that some basic elements of constancies may be innate (I'll try and find that study in a tick - this is just from memory.) I'll get back to you on that one though, I'll do some more research on it.

Perhaps someone with a university psychology text book + psychology database will be able to provide some more insight into the last question?

I remember my Psych teacher referring to a study related to the Muller-Lyer illusion, where they tested that illusion to people in African villages, who's houses are round, not square like ours. It turned out that such people don't get tricked like us Westerners would.

But, to answer the question, I'm not quite sure myself. I will have a look if I finish all my work tonight.

(If I'm really desperate, I might e-mail Dr Max Jory, who actually lectures this at Monash and who may be familiar to you if you have ever used the Checkpoints books)

[d0minicz]

thank youuuuuuuu
Could we experience two different states of consciousness simultaenously? Explain.
thanks guys

[Glockmeister]

thank youuuuuuuu
Could we experience two different states of consciousness simultaenously? Explain.
thanks guys

Umm... a hard hitting question here. We are getting into the realms of Philosophy here.

Don't take this as truth or anything, but I think you need to treat states of consciousness as a sort of sliding scale. In other words, you can't experience two states of consciousness simultaneously. But you can slide from one state of consciousness to another fairly quickly.

Remember also that consciousness is a hypothetical construct as well. That makes it really hard to give you a definitive answer. This is good for you thought, because I'm pretty sure that means that it won't be a question asked in the exam.

EDIT: I meant you can't experience two states of consciousness, not you can. Sorry.

[cns1511]

thank youuuuuuuu
Could we experience two different states of consciousness simultaenously? Explain.
thanks guys

Umm... a hard hitting question here. We are getting into the realms of Philosophy here.

Don't take this as truth or anything, but I think you need to treat states of consciousness as a sort of sliding scale. In other words, you can experience two states of consciousness simultaneously. But you can slide from one state of consciousness to another fairly quickly.

Remember also that consciousness is a hypothetical construct as well. That makes it really hard to give you a definitive answer. This is good for you thought, because I'm pretty sure that means that it won't be a question asked in the exam.

I was thinking that you can't experience two states of consciousness at once since its the level of awareness at a given time (which couldn't possibly be two different levels). However, you could how be in between 2 of the states of consciousness you learn (because we don't know all of the exact levels, etc) so, you could be between divided attentioand daydreaming for example.

[Glockmeister]

ok...

cones are not DIRECTLY connected to retinal ganglion cells, they contact bipolar cells which contact RGC. two ways in which info. from cones can flow to RGC- direct pathway from receptors to bipolar cell to RGC and an indirect pathway where horizontal cells and amacrine cells are invovled....won't go into detail here...acuity comes from receptor field size and the amount of convergence.. acuity is highest at the fovea and descreases peripherally...



property                   foveal (cone) vision                    non foveal (rod) vision

directionality               axial only                                 any direction                             

wavelength sensitivity     colour vision                             non colour vision   

absolute sensitivity          low sensitivity, day vision            high sensitivity, night vision


type object detection        detects rapidly                                        detects slowly, detects only slowly
                                     detects rapidly moving/changing objects           moving/changing objects


acuity of vision                 high acuity, fine detail vision                           low acuity, detection vision

Yeah, I was in a rush and I didn't have time to really go into the nitty gritty. Also, that could be more of a transmission process.

[d0minicz]

Describe two important differences between controlled and automatic processes in normal waking consciousness.
yeah just need verification .
thanks.