From previous research, we expected to find a two main factor solution: Affective Valence, comprising affective valence ratings, magnitude, and latency of the startle reflex, and heart-rate change, and Arousal, made up of arousal ratings, SCR, and picture-viewing time.
The data of one subject were unavailable for startle blink reflex (n = 44), heart-rate data of one subject were discarded from statistical analysis due to intractable recording artifacts (n = 44), and SCR data of one subject were discarded due to a low rate of responses (< 2; n = 44).
Startle probes were presented at two of three pictures of each affective category per block, at a random time between 3500 and 4500 ms after picture onset.
The acoustic startle stimulus was a 50-ms 105-dB(A) burst of white noise (20 Hz-20 kHz) with instantaneous rise- and fall-times, presented binaurally through Sony MDR-P70 headphones, and generated by a custom-made noise acoustic stimulator from the facilities of the University of Murcia.
If the resident is hitting because of an exaggerated
startle response, the caregiver should approach from the front with a smile, being sure to gain the resident's attention and to precede the physical contact with eye contact.
The researchers examined the startle reactions of 17 healthy individuals who, on different occasions, did or did not know when a blank pistol would be fired.
Within 200 milliseconds after an unanticipated startle, most subjects displayed horizontal stretching of the lips, tightening of eye and neck muscles, eye blinking, eyebrow lowering and jerking of the head and trunk.
With emotions such as surprise, happiness and disgust, note the researchers, facial expressions can be inhibited and simulated fairly successfully and are far more difficult to elicit experimentally than is the startle reaction.
