Assignment 2.1

Due: Sunday, End of Module by 11:55 p.m. EST

This assignment will be short answers that reflects the material covered in this module.  Please complete in APA format without an abstract.  You may list the questions and then answer them in chronological order. The assignment should be about 2-3 pages.  Thus, the answers should be short and descriptive. 

Each question if worth 12.5 pts.

  1.  There is a debate within the field of psychology in reference to the cause of human behavior.  It is called the nature/nurture controversy.  Last module we examined the differing fields of psychology, and this week examined behavior from an evolutionary and biological standpoint.  What is behavioral psychology and their standpoint on the cause of human behavior.  Similarly, this week we looked at evolutionary and biological psychology.  What is the field of thought from this area of study.  In addition, how are twin and adoption studies used as a means of trying to understand behavior and yet provide environmental control?  What do you think the cause of human behavior is?  Is it a combination of environment, experience and genetics, or predominantly one of these? 
  2. Gestalt psychologists noted certain consistencies in the way we integrate bits and pieces of sensory stimulation into meaningful wholes.  They grouped these rules into the laws of perceptual organization.  Please discuss and explain the following:  Figure-ground perception, proximity/similarity, continuity/closure and top-down versus bottom up processing.
  3. What causes objects to appear to follow us as we look out a window while riding in a car?  Or, what causes nearby objects such as trees to go by rapidly?  Similarly, what other monocular cues create depth illusion?
  4. The principles of perceptual organization make it possible for our eyes to play tricks on us.  These are called optical illusions.  What are the Hering-Helmholtz and the Muller-Lyer illusions and how do they occur?

5.What types of non-invasive measures can be taken when there is an interest in doing research that involves areas of the brain?  For example, I am a researcher interested in studying sleep research or to see if certain subjects with schizophrenia have different brain structures.  What brain measuring or imaging techniques might I use?

  1. What is the meaning of absolute threshold and just noticeable differences?  How can this be differentiated in terms of sound, weight, light and taste?



Writing Requirements


  • APA format, 3–4 pages in length (excluding cover page, abstract, and reference list)


Grading Criteria:


  • This assignment will be graded using the UOTP Writing Rubric displayed below


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 PSYC 201 – Principles of Psychology


Q1: Cause of human behavior

The debate about nature and nurture has been used over decades in field of psychology in an attempt to study and explain the cause of individual human behavior. Generally, nature studies the genetic and inheritance traits that influence human behavior while nurture is much more concerned with the study of environmental factors and experiences that influence human behavior. I believe that both the biological, environmental, and evolutionary standpoint significantly contributes in influencing human behavior. For instance, the study of identical twins with similar genetic characteristics has contributed a lot in studying how genes influence human behavior (Tellegen et al., 1988). It is evident from the study that genetic and inheritance traits significantly contribute about half of human behavior and development. Additionally, the role played by environmental and evolution factors cannot be underestimated. Despite the biological influence, the environmental factors such as peer influence, parental guidance, and the culture from which an individual was reared or lives in significantly influence personal characteristics (Lickliter, & Honeycutt, 2003). Moreover, it is worth noting that everyone is born an intelligent agent with the ability of learning and acquiring knowledge from early childhood to adulthood. It is during this process that an individual associate with others in the society, observe their behaviors, learn, develop and adapt personal behavior and characteristics (Lorenz, 1965). It is therefore admittedly that interaction between genetic, environmental and experience factors influence human behavior.

Q2: Gestalt laws of perceptual organization.

Figure-ground perception: This explains the ability of the visual system in separating and identifying a figure and a background/ground when looking at something (Wertheimer, 1938). The figure is the most relevant point of view while the rest part is the background. According to this law, color composition, brightness, contrast, blurriness, size and object separation help to accomplish this vision.

Proximity/similarity: This Gestalt law of perceptual organization explains that when objects are near each other, they are perceived as to belong to a similar group and not separately.

Continuity/closure: The law of continuity explains that a figure is perceived as complete if it is connected in a straight line or a circular path without a break while the law of closure alleges that the brain and the visual system have a tendency of forming a sensation and creating a meaningful perception from an incomplete visual object following a pattern.

Top-down and bottom-up processing: these are methodologies used to understand the perception process. Top-down processing approach refers to contextual information in the brain to recognize patterns while bottom-up processing approach refers to the use of stimulus such as eyes and ears to pass information to the brain to generate visual perception.

Q3: Monocular cues

The cause of static objects to appear as moving when we look outside while driving is motion parallax. This a monocular depth cue that is cause by a change of an object’s position relative velocities as perceived by the retina while driving. Additionally, relative size is also another monocular cue that explains that an observer perceives a smaller object far away than a larger object. Ariel perspective is also another cue that explains that an object that is far from an observer appear to be blurred because of atmosphere.

Q4: Hering-Helmholtz and the Muller-Lyer optical illusions

The Hering-Helmholtz illusion is a geometrical-optical illusion that was conducted on two straight parallel lines (Coren, Ward, & Enns, 2004). It was observed that despite the two lines being straight and parallel, the appeared to be curved as a result of other visual image background effects. The cause of this distortion is likely created by the tendency of our perceptual system to transform acute angles. On the other hand, Müller-Lyer illusion is a visual illusion where two arrow headed equal lines are used to investigate visual perception (Jahoda, 1971). The arrows in one line are pointing inward while in the other points outward. When the two lines are observed, the illusion created is that the line with inwards pointing arrows is longer than the other. This illusion is created by the perception of the brain of interpreting angles as the base to judge sizes leading to a misleading information.

Q5: Noninvasive brain measuring or imaging techniques

Positron emission tomography is among the effective techniques that can be used during an invasive brain research. Basically, this technique involves injection of a metabolic active chemicals that emit radiations. The emitted radiation data is measured and processed using a computer to produce images that show how the metabolic chemicals accumulates and are distributed in the brain. This scan significantly helps to show the rate of blood is flow as well as glucose metabolism in the brain which reflect the activities of the brain. Additionally, electroencephalography is also another noninvasive process that can be used to measure and record neural activity by placing electrodes on the surface of a human head.

Q6: Absolute threshold and just noticeable differences

Absolute threshold is the minimum amount of stimulus that can be detected by a person while just noticeable difference is the smallest noticeable difference stimulus that can be detected at least 50 percent when comparing two objects. In relation to vision, this can be differentiated in terms of the smallest photons that an individual can detect. Additionally, the minimum level of smell that an individual can sense and also the lowest sound that a normal person can hear differentiates both taste and sound respectively.


Coren, S., Ward, L. M., & Enns, J. T. (2004). Sensation and perception.

Jahoda, G. (1971). Retinal pigmentation, illusion susceptibility and space perception. International Journal of Psychology, 6(3), 199-207.

Lickliter, R., & Honeycutt, H. (2003). Developmental dynamics: toward a biologically plausible evolutionary psychology. Psychological bulletin, 129(6), 819.

Lorenz, K. (1965). Evolution and modification of behavior (No. 150 L6). Chicago: University of Chicago Press.

Tellegen, A., Lykken, D. T., Bouchard, T. J., Wilcox, K. J., Segal, N. L., & Rich, S. (1988). Personality similarity in twins reared apart and together. Journal of personality and social psychology, 54(6), 1031.

Wertheimer, M. (1938). Laws of organization in perceptual forms