Why did later ethologists move away from drive and energy models of instinct?

Later ethologists moved away from drive and energy models of instinct due to significant conceptual and empirical shortcomings in the theories proposed by early figures like Konrad Lorenz and Nikolaas Tinbergen.12

The primary reasons for this shift include:

• Incompatibility with Physiology: The concept of "action-specific energy" accumulating and being "expended" bore little resemblance to actual nervous system function. While these models might have loosely described hormonal processes, they failed to account for the realities of neural transmission, which is the primary mechanism of behavioral control.12
• Lack of Empirical Evidence: Attempts to find overt quantitative indices for these drive states often produced inconsistent results, suggesting that behavior is not driven by a single, unitary force.1
• Complexity of Behavioral Control: Research, particularly by Robert Hinde in the 1960s, demonstrated that the causal basis of behavior is dispersed across numerous variables affecting sensory, central, and motor pathways, rather than being a simple hierarchical discharge of energy.1
• Shift to Decision Theory: Ethologists increasingly adopted decision theory, which views animals as selecting actions based on assessments of costs and benefits in specific situations, rather than merely reacting to internal "dammed up" energy.1