1)  How do the details in each image differ?  Be specific; describe the changes in good visual detail.

The details differ in a few different ways.  Lange captures a more close up view of the migrants as the series progresses.  Through this we first see the details of the residence as a whole in the beginning image, which provides an overview of their situation.  The final three images bring the emotional expressions of the mother and her children into focus while also bringing to mind the obvious fact that the family lives in harsh, impoverished conditions.
 

2)  Does your perception of the people in the photograph change with each image?

My perception of the people in the photograph does not change with each image.  The first image elicits disbelief that people managed to live in such desolation.  This theme becomes reinforced in the following images mostly through the facial expressions of both mother and children.  Adversity challenges all aspects of life as portrayed through the family's living conditions and environment, ultimately finalized as truth in my mind through the power of their body language and facial expressions.
 

3)  Consider the artistic decisions Lange made and how those decisions/strategies elicited a desired emotional response from the viewer.  Do you think the subjects in the photograph were instructed how to pose or did Lange capture them as they were?

While I think that Lange may have directed the poses in the images, the environment and state of the people in the images seems genuine.  Sadness exudes from every individual shown and this transmits to the viewer the fact that these people lead a very difficult life.
 

4)  Which image did you find most sympathetic and why?

I find the final image the most sympathetic because it seems to relay a sense of despair.  The mother is holding her infant while the other two young children turn away, seemingly upset or crying over her shoulder.  Mother also has her hand at her mouth accenting the vacant, worried look in her eyes.
 

5)  The photographs are presented as "a series."  Does your emotional response to the photographs change as the composition changes?

My emotional response becomes progressively more sympathetic as the series continues.  This occurs partly because of the close relation each image has with one another.  By this I mean that the effect of one image still lingers as I view the next image, effectively escalating my emotional response.  This effect culminates with the last and final image.
 

6)  How could these images be used as arguments?

These images could be used as arguments through the way they show living conditions of migrant farm workers during the Great Depression.  Lange's series does a great job of capturing the reality of the hardships that this subclass of workers faced in order to survive.