Which of the following illustrates seriation?

A) The ability to place sticks in order according to size
B) The ability to understand that hidden objects still exist
C) The ability to understand that flattening a ball of clay does not change its mass
D) The ability to understand another person's point of view

The fact that human aggression varies widely from culture to culture most strongly suggests that it is NOT

A) a reaction to frustration.
B) influenced by social norms.
C) an unlearned instinct.
D) a product of deindividuation.

Which of the following occurs in the expulsion stage of ejaculation in men?

A) The bladder's sphincter muscle closes to prevent urine from mixing with the semen and semen from entering the bladder.
B) There are rapid, rhythmic contractions of the urethra, the prostate, and the muscles at the base of the penis.
C) Men feel a highly distinct sensation of ejaculatory inevitability.
D) A sphincter below the prostate closes to trap semen in the expanded urethral bulb.

Twins formed by the fertilization of two ova by two sperm are

A) fraternal.
B) the least common type of twins.
C) genetically the same.
D) more likely in first pregnancies than in later ones.

Women tend to find divorce more difficult than men because ______.

A) women ruminate more about arguments
B) men have more detailed memories of conflicts
C) women take arguments less personally
D) men feel less depressed after arguments

With sleep deprivation,the levels of leptin ________ and the levels of ghrelin ________.

A) rise;rise
B) fall;fall
C) rise;fall
D) fall;rise