From the blog ‘Predictably Irrational’ by Dan Ariely, behavioral scientist at M.I.T. and author of ‘Predictably Irrational‘, here’s a personal account of the identifiable victim effect:

The story described a 911 call in which the dispatcher could hear Mrs. Schneider being slapped and her say, “Mark, you hit me. I’m bleeding.” The dispatcher heard a second slap noise and another call for help. The officer who arrived two minutes later and saw Mrs Schneider, covered in blood, in her front yard with her son Mark hitting her on the head with wooden baseball bat. The police officer drew his pistol and ordered Mark to stop, but Mark struck his mother in the head again and again until the officer was able to use his Taser and Mark dropped to the ground. Mrs, Schneider was rushed to Hartford Hospital for treatment of two broken forearms and a skull fracture, while Mark was taken to the police headquarters, and from there to the psychiatric unit at the local Hospital.
I was deeply saddened after reading these reports, but the story that I could not get out of my head for the next few days, was not the large devastation of Hurricane Ike, it was the tragedy of the Schneider family.

For the whole story, see: The Identifiable Victim Effect in ActionVictims whose stories we know are more likely to elicit sympathy, 10/1/2008

Scoville and Milner. Loss of Recent Memory After Bilateral Hippocampal Lesions. Journal of Neurology, Neurosurgery and Psychiatry (1957) vol. 20 (11) pp. 11-21

In The Interpretation of Dreams, Ch V (p. 210-211 of the Avon edition, Strachey translation, Freud argues:

And there is another objection that can be raised to Robert’s theory. If it were really the business of dreams to relieve our memory of the ‘dregs’ or daytime recollections by a special psychical activity, our sleep would be more tormented and harder worked than our mental life while we are awake. For the number of indifferent impressions from which our memory would need to be protected is clearly immensely large: the night would not be long enough to cope with such a mass. It is far more likely that the process of forgetting indifferent impressions goes forward without the active intervention of our psychical forces.

The argument has two parts: the first is a rejection of Robert’s theory that psychic forces are active in the process of forgetting the minutia of daily experiences while sleeping. The second posits that a more likely explanation for this phenomenon is that the psychic forces are not active.  The mechanism of forgetting posited by Freud is, of course, left to other sections of the work.

Thus, the argument that is the most interesting for our puposes here is the first.  The first sentence tells us Freud is objecting to Robert’s theory.

The second sentence in the quotation asserts a conditional:

(1) If it were really the business of dreams to relieve our memory of the ‘dregs’ or daytime recollections by a special psychical activity, our sleep would be more tormented and harder worked than our mental life while we are awake.

Let us formalize this argument by split this into its two parts and removing the qualifiers. The antecedent is (take from the subjunctive tense and put in the literary present):

(1a) it is the business of dreams to relieve our memory of the ‘dregs’ or daytime recollections by a special psychical activity

And the consequent is:

(1c) our sleep is more tormented and harder worked than our mental life while we are awake.

The use of the subjunctive tense here has already shown that Freud believes the antecedent false. We therefore know that this argument is intended as a form of modus tollens.

Thus, to complete the objection to Roberts, Freud needs to connect Robert’s theory with the antecedent, and demonstrate that the consequence is false.

Checking back over the text (Ch 1, section G or p. 110-111 in the same edition), we find that Freud characterizes Robert’s position as holding that “Dreams serve as a safety-valve for the over-burdened brain.” He quotes Robert as saying that ‘A man depraved of the capacity for dreaming would in course of time become mentally deranged, because a great mass of uncompleted, unworked-out thoughts and superficial impressions would accumulate in his brain and would be bound by their bult to smother the thoughts which should be assimilated into his memory as completed wholes.’ Fair enough. “dregs of daytime recollections” is equivalent to the “great mass of uncompleted, unworked-out thoughts and superficial impressions” and “relieve” is the process of assimilating these “into his memory as completed wholes.”

All Freud needs to do then is provide the negation of the consequent and draw the conclusion.  The intended negation must then be contained in the third sentence:

For the number of indifferent impressions from which our memory would need to be protected is clearly immensely large: the night would not be long enough to cope with such a mass.

Again, we can split this into two parts.  The first must be seen as an extension of the antecedent: the ‘uncompleted, un-worked out thoughts and superficial impressions’ are compressed into ‘indifferent impressions,’ which are immensly large in number. The heart of the argument, then, is Freud’s assertion that the night would not be long enough to cope with this ‘immensely large’ mass. We can formalize these premises, tying them into the first, thus:

(2) The number of different ‘dregs’ of daytime recollections is immensely large.

(3) The night is not long enough to cope with an immensely large number of daytime recollections.

But that’s where the argument is an enthymeme: nowhere has Freud, or Roberts, made a claim about the computational speed of the mind.  To truly complete the argument, Freud needs the premise that:

(2) The number of different ‘dregs’ of daytime recollections is larger than the mind can process in a single night.

And that’s not exactly the same as what he asserts. The reformed (2) still doesn’t match the consequent in (1c), so we’ll have to allow that processing such a large mass would create tormenting, hard work for the mind–at least, more tormented and harder worked than daily life. On a charitable reading, then, we can recharacterize Freud’s argument thus:

IF (1a) it is the business of dreams to relieve our memory of the ‘dregs’ or daytime recollections by a special psychical activity THEN (1c) our sleep is more tormented and harder worked than our mental life while we are awake.

(2) The number of different ‘dregs’ of daytime recollections is larger than the mind can process in a single night.

(3) processing such a large number of ‘dregs’ in a night would make the mind more tormented and harder worked–at more than being awake.

(4) Sleep does not make the mind more tormented and harder worked than being awake.

(5) Therefore, it is not the business of dreams to relieve our memory of the ‘dregs’ or daytime recollections by a special psychical activity