This process tactic happens when an offer is made that is unsatisfactory and no counter comes quickly. The offeror may then wait and resist correcting (as many are schooled not to negotiate against themselves) what may be a bad, trial, or probing offer. The offeror lets great gaps of time pass, running the clock and creating time pressure. There is an anxiety around responding to offers like this, especially if they are complex.
An offer is made. Time passes. Offeror gets nervous and makes a second, more generous offer, for fear that the deal is going away. The second offer is effectively negotiating against oneself.
The issue here is to prompt a response or motivate to a prompt response without an eager tone. If you are the buyer using the Waiting Dark tactic, you are waiting for the seller to follow up with a modified offer; if you’re the seller then you might follow up in a different way by forwarding an article or information discussing urgency or scarcity to trigger closing. You may also lighten the darkness with open ended questions, such as, “Is that your best and final offer? Do you think that is realistic?” Or even, “I thought you were joking.”