398 Iv. COGNITI vE AND M OTIvATIONAL P ROCESSES
showed that administration of a drug that 
increases central dopamine, a key transmit -
ter in reward prediction and reinforcement 
processes in the midbrain and the striatum, 
leads to increased n Achievement, whereas 
administration of a drug that decreases do -
pamine leads to reduced levels of this mo -
tive. Other research suggests a link between 
n Achievement and the peptide hormone 
arginine vasopressin (AVP), which regulates 
water retention in the body and memory 
processes in the brain. McClelland (1995) 
reported evidence that individuals high in 
n Achievement urinate less and have bet -
ter story recall after achievement arousal. 
Although these findings support the n 
Achievement–  AVP hypothesis, it has not 
been tested directly yet.
Finally, recent research points to a role of 
n Achievement in stress response regulation. 
Individuals high in n Achievement show an 
attenuated HPA stress response to one-on-
one competitions, to stressful social evalu -
ation tasks (Schult  heiss et al., 2014), and to 
negative performance feedback (Yang, Ram -
say, Schult  heiss, & Pang, 2015). They also 
exhibit greater SNS activation in response 
to challenging, but not to easy or impossibly 
difficult, tasks (Brunstein & Schmitt, 2010). 
Consistent with the characterization of n 
Achievement as a preference for challenges 
outlined earlier, these findings suggest that 
achievement-  motivated individuals view 
difficult tasks not as threats, which would 
preferentially lead to HPA activation, but as 
challenges, which engage the SNS.
Core Motivational Functions 
of Implicit Motives
Current theorizing in motivation science 
emphasizes the role of affective respons -
es to incentives and disincentives as the 
prime mover of motivation (see Schult  heiss 
& Wirth, 2018, for a review). According 
to Berridge (1996; Berridge & Robinson, 
2003), the motivational process consists of 
two consecutive, functionally interdepen -
dent phases, termed wanting  and liking . 
Liking denotes the primal affective response 
to rewards (pleasure) and punishments 
(pain), that is, to what learning theory has 
termed unconditioned stimuli . Cabanac (2014) holds that such hedonic responses 
signal the usefulness, or harmfulness, of a 
stimulus, event, or situation for an organ -
ism’s survival, depending on the organism’s 
current needs. They thus represent a com -
mon currency for evaluating the utility of 
outcomes that can otherwise be very diverse 
(e.g., food, safety) along one dimension. 
How much pleasure or pain an uncondi -
tioned stimulus generates—  how much it 
is liked or disliked—  has consequences for 
how much it is wanted in the future, that 
is, how emotionally compelled an organ -
ism will feel to pursue it, how much energy 
it is willing to invest in its attainment or 
avoidance, how much attention to predic -
tive cues (conditioned stimuli) and their 
situational contexts it will pay, and how 
well it will retain (or inhibit) behaviors that 
have brought about the reward (or punish -
ment). Of course, the relationship between 
wanting and liking is an iterative process 
that after every motivational episode needs 
to recalibrate, through the outcome evalua -
tion represented by liking, whether less, the 
same, or more wanting will be appropri -
ate in the future (see Rescorla & Wagner, 
1972). In the following, we present a model 
of implicit motives that anchors them in the 
liking phase of motivation, as generators of 
hedonic responses to motive-  specific incen -
tives and disincentives, and that describes 
their effects on components of the wanting 
phase as consequences of this fundamental 
function (see Figure 18.2 for an overview).
Motives Are about  Liking: Hedonic  Responses 
to Incentives and  Disincentives
Atkinson (1957) argued that a motive rep -
resents a capacity to have a strong affective 
response to motive-  specific (dis)incentives— 
this is the basis of the motive definitions we 
gave at the beginning. Thus, the strength of 
an implicit motive determines the strength of 
individuals’ affective responses to a motive- 
specific unconditioned stimulus, turning 
incentives into something pleasurable and 
rewarding and disincentives into something 
painful and aversive. Without a motive, 
there is no hedonic response to such stimuli.
Evidence for an affect-  scaling function 
of implicit motives comes from studies of 
facial expressions, which represent a prime 