Science fiction genre

This was really helpful to me as my essay was on this question on orginality and repetition in a chosen genre but, the thing i found interesting the most was that in the alien film they used a puppet to get a better reaction from the actors and acctresses this is because they would have had used a tennis ball on a stick which would not have the same reaction because the actors and actresses would be imaging what they think it would look like and especially as they did it in one take and it was the first time they had seen what it looks like also since seeing this and it helping in my essay i have gone out and brought alien on dvd and it is the first time i have watched it properly but most of all it has really helped my work.