The effect of (un)pleasant sounds on the visual and overall pleasantness of products

THE EFFECT OF (UN)PLEASANT SOUNDS O N THE

VISUAL AND OVERALL PLEASANTNESS O F PRODUCTS

Elif Özcan

Hendrik N.J. Schifferstein Delft University of Technology Faculty of Industrial Design Engineering E l e.ozcan@tudelft.nl

E l h.n.j.schifferstein@tudelft.nl ABSTRACT

A product is a nnulti-sensory object and eacli sensory property can contribute to the product experience. In this study we investigated the effect of sound (pleasant, unpleasant, original, and no sound) on the perceived pleasantness of products (i.e., visual pleasantness and over-all pleasantness). Results indicate that ratings for visual and overover-all pleasantness are similar when no sounds are provided with the products (pictures). When participants are provided with sounds corresponding to the product, however, the overall pleasantness ratings decreased and visual pleasantness increased. Furthermore, while original and unpleasant sounds had a nega-tive effect, pleasant sounds had a posinega-tive effect on visual and overall pleasantness ratings. We suggest that if efforts are put into improving the sound quality users will be more pleased and more willing to interact with products.

KEYW/ORDS: product sounds, visual pleasantness, overall pleasantness, experiences, audio-visual

interactions.

INTRODUCTION

I m a g i n e y o u r s e l f in a s t o r e w h e r e h o u s e h o l d a p p l i a n c e s a r e s o l d . You n e e d a coffee m a k e r f o r y o u r k i t c h e n . There are sev-e r a l o f t h sev-e m o n t h sev-e d i s p l a y a n d y o u c o n t sev-e m p l a t sev-e sev-each cof-f e e maker in t e r m s o cof-f its cof-f u n c t i o n a l i t y , ease o cof-f u s e , a n d l o o k s . You f i n a l l y c h o o s e t h e o n e t h a t y o u like t h e m o s t . A f t e r y o u r p u r c h a s e y o u t a k e t h e p r o d u c t h o m e a n d p l u g it i n . A w i l d r o a r i n g m o t o r s o u n d e m i t t i n g f r o m t h e p r o d u c t s t a r t l e s y o u . You f e e l d i s a p p o i n t e d . The u n p l e a s a n t s o u n d o f t h e p r o d u c t o v e r s h a d o w s t h e p l e a s a n t e x p e r i e n c e y o u had i n c h o o s i n g i t , a n d t h e Joy a n t i c i p a t e d w i t h t h e use o f t h e p r o d u c t . You are no longer p l e a s e d w i t h y o u r c h o i c e . A p r o d u c t i n h e r e n t l y f a c i l i t a t e s a m u l t i - s e n s o r y e x p e r i e n c e w i t h its v i s u a l , a u d i t o r y , t a c t i l e , a n d c h e m o s e n s o r y p r o p e r -t i e s . D u r i n g everyday p r o d u c -t e x p e r i e n c e s , p e o p l e p e r f o r m a c t i o n s w i t h t h e p r o d u c t , t h e y p e r c e i v e s e n s o r y s t i m u l a t i o n in d i f f e r e n t m o d a l i t i e s , t h e y b e c o m e a w a r e o f t h e m e a n i n g s a n d values t h e y a t t a c h t o t h e p r o d u c t , a n d t h e y can o b s e r v e a n y feelings a n d e m o t i o n s t h a t are e l i c i t e d ( e . g . , H e k k e r t & S c h i f f e r s t e i n , 2 0 0 8 ; Özcan & v a n E g m o n d , 2 0 0 9 ) . As f a r as p r o d u c t a e s t h e t i c s are c o n c e r n e d , a l l t h e s e n s o r y m o d a l i t i e s c a n c o n t r i b u t e t o p l e a s a n t e x p e r i e n c e s (Suzuki e t a l . 2 0 0 6 ; Fenko e t a l . , 2 0 1 0 ; S c h i f f e r s t e i n & H e k k e r t , 2011), a n d c o n

-s u m e r p r o d u c t -s c a n evoke feeling-s o f inten-se e n j o y m e n t in m u l t i p l e w a y s .

S o u n d may play a n i m p o r t a n t role in h o w p e o p l e p e r c e i v e a n d j u d g e p r o d u c t s o n p l e a s a n t n e s s . For i n s t a n c e , f o r an e s p r e s -so m a c h i n e o r a s p o r t s c a r t h e q u a l i t y o f t h e s o u n d c l e a r l y c o n t r i b u t e s t o t h e p l e a s a n t n e s s o f t h e i r usage e x p e r i e n c e . However, as e x e m p l i f i e d a b o v e , t h e p l e a s a n t n e s s o f e l e c t r i -c a l p r o d u -c t s in t h e a b s e n -c e o f s o u n d m a y n o t -c o r r e s p o n d t o t h e i r p l e a s a n t n e s s d u r i n g use w h i l e p r o d u c i n g s o u n d . W i t h regard t o o u r d a i l y i n t e r a c t i o n s w i t h p r o d u c t s , w e c a n m a k e c o n c e p t u a l d i s t i n c t i o n s b e t w e e n d i f f e r e n t kinds o f p l e a s a n t -ness J u d g m e n t s . Ideally, visual pleasant-ness J u d g m e n t s are t h e r e s u l t o f a p e r c e p t u a l process based solely o n t h e p r o d -uct's a p p e a r a n c e , w h e r e a s overall pleasantness J u d g m e n t s r e f l e c t an e v a l u a t i o n based o n t h e m u l t i s e n s o r y i n t e r a c t i o n i n c l u d i n g i t s t a c t i l e , h a p t i c , a u d i t o r y , a n d c h e m o s e n s o r y p r o p e r t i e s . H o w e v e r , b o t h v i s u a l a n d o v e r a l l p l e a s a n t n e s s J u d g m e n t s m a y be i n f l u e n c e d n o t o n l y by t h e presence o f t h e s o u n d b u t also b y t h e q u a l i t y o f t h e s o u n d . That is, p l e a s a n t p r o d u c t s o u n d s m a y f a c i l i t a t e a m o r e p l e a s a n t e x p e r i e n c e w i t h a p r o d u c t c o m p a r e d t o t h e u n p l e a s a n t s o u n d s , w h i c h may cause an u n d e s i r e d e x p e r i e n c e . There is e m p i r i c a l e v i -d e n c e t h a t users c a n -d i s t i n g u i s h b e t w e e n v i s u a l p l e a s a n t n e s s a n d o v e r a l l p l e a s a n t n e s s . In a s t u d y t h a t t a c k l e d t h e e f f e c t

Salamanca, J, Desmet, P., Burbano, A., Ludden, G., Maya, J (Eds.). Proceedings of the Colors of Care: The 9th International Conference on Design & Emotion. Bogota, October 6-10,2014. Ediciones Uniandes, Bogota, 2014 ISBN: 978-958-774-070-7 601

of s o u n d on l a n d s c a p e e x p e r i e n c e . Carles, Barrio a n d De L u -cio (1999) f o u n d t h a t p l e a s a n t n e s s r a t i n g s w e r e h i g h e r w h e n l a n d s c a p e s o u n d s o r images w e r e r a t e d s e p a r a t e l y r a t h e r t h a n c o m b i n e d . N o n e t h e l e s s , Carles et a l . also s h o w e d t h a t s o u n d s w i t h p o s i t i v e a s s o c i a t i o n s ( e . g . , w a t e r ) i n c r e a s e d t h e o v e r a l l p l e a s a n t n e s s r a t i n g s . P r o d u c t s o u n d s are m a i n l y c o n s e q u e n c e s o f t h e ways p r o d -ucts o p e r a t e ( e . g . , m o t o r s , f a n s , a n d so o n ) o r t h e y give f u n c t i o n a l f e e d b a c k o n user a c t i o n s ( e . g . , b u t t o n s o u n d s ) , and t h e y are g e n e r a l l y n o t c r e a t e d t o a d d t o t h e p l e a s u r e o f p r o d u c t use ( L a n g e v e l d , e t a l . , 2013). P r o d u c t s o u n d s are p e r c e i v e d as l o u d , s h a r p , a n d noisy, w h i c h leads t o u n p l e a s -a n t sensory e x p e r i e n c e s o n p s y c h o -a c o u s t i c -a l g r o u n d s (Öz-c a n , 2 0 0 8 ) . As a (Öz-c o n s e q u e n (Öz-c e , m o s t p r o d u (Öz-c t s o u n d s are n o t e v a l u a t e d f a v o r a b l y w h e n j u d g e d i n d e p e n d e n t l y ( B i j s t e r v e l d , 2 0 0 8 ; Özcan & van E g m o n d , 2012). H e n c e , a l t h o u g h p r o d u c t s o u n d s are o f t e n necessary in p r o v i d i n g i n f o r m a t i o n o n t h e stages o f p r o d u c t f u n c t i o n i n g ( e . g . , w a s h i n g cycle a n d s p i n cycle o f w a s h i n g m a c h i n e s ) , t h e y are u n l i k e l y t o e n h a n c e o v e r a l l p r o d u c t p l e a s a n t n e s s e v a l u a t i o n s if t h e y are per-ceived as u n p l e a s a n t . S o u n d s in g e n e r a l c a n a f f e c t a n e x p e r i e n c e a d v e r s e l y i f l i s -t e n e r s d o n o -t have c o n -t r o l o v e r -t h e p r o d u c -t i o n o f -t h e s o u n d a n d i t s q u a l i t y ( M a r i s , 2 0 0 8 ) , w h i c h is o f t e n t h e case f o r p r o d u c t s o u n d s . For e x a m p l e , t h e l o u d , r o u g h , a n d h i g h p i t c h e d s o u n d o f a l a d y e p i l a t o r can c o n t n b u t e t o t h e n e g a t i v e r e a c t i o n s t o w a r d s t h e p r o d u c t itself. A n a t t e n t i o n d e -m a n d i n g s o u n d is -m o r e i n t r u s i v e a n d , t h e r e f o r e , c o n s i d e r e d as less p l e a s a n t c o m p a r e d t o a n o n - a t t e n t i o n d e m a n d i n g s o u n d ( B e r g m a n e t a l . , 2 0 0 9 ) . N o n e t h e l e s s , i f w e c o m p a r e t h e e f f e c t s o f d i f f e r e n t t y p e s o f s o u n d s on p r o d u c t e x p e r i -e n c -e s , w -e -e x p -e c t t h a t p r o d u c t s w i t h r -e l a t i v -e l y p l -e a s a n t s o u n d s w i l l e v o k e m o r e p o s i t i v e o v e r a l l e v a l u a t i o n s t h a n p r o d u c t s w i t h r e l a t i v e l y u n p l e a s a n t s o u n d s . For e x a m p l e . Van Balken ( 2 0 0 2 ) s h o w e d t h a t i m p r o v i n g t h e a u d i t o r y q u a l -i t y o f c o f f e e m a c h -i n e s t h r o u g h m e c h a n -i c a l c h a n g e s s h -i f t e d t h e e m o t i o n a l a n d s e m a n t i c e x p e r i e n c e s o f p r o d u c t s f r o m n e g a t i v e t o p o s i t i v e . S i m i l a r l y , L a g e a t , Czellar, a n d L a u r e n t ( 2 0 0 3 ) e s t a b l i s h e d l i n k s b e t w e e n t h e a c o u s t i c a l c o m p o s i -t i o n s o f s o u n d s -t o u s e r s ' e x p e r i e n c e s o f l u x u r y . In S p e n c e a n d Z a m p i n i ' s ( 2 0 0 6 ) s t u d y , p a r t i c i p a n t s r e p o r t e d t h a t b r u s h i n g t h e i r t e e t h w i t h a n e l e c t r i c t o o t h b r u s h f e l t m o r e p l e a s a n t a n d less r o u g h i f e i t h e r t h e o v e r a l l s o u n d l e v e l w a s r e d u c e d o r t h e h i g h f r e q u e n c y s o u n d s w e r e a t t e n u a t e d . A l l t h e s e s t u d i e s i n d i c a t e t h a t b y c h a n g i n g t h e a u d i t o r y q u a l -ity o f s o u n d s , d e s i g n e r s c a n o b t a i n m o r e p l e a s a n t p r o d u c t e x p e r i e n c e s . W h e n p e o p l e e n c o u n t e r p r o d u c t s , d i f f e r e n t s o u r c e s o f s e n -sory s t i m u l a t i o n t y p i c a l l y are n o t p e r c e i v e d s i m u l t a n e o u s l y . From a b i o l o g i c a l p e r s p e c t i v e , t h e s e n s o r y c h a n n e l s may o p e r a t e q u i t e i n d e p e n d e n t l y in t e r m s o f s t i m u l u s r e c e p t i o n , b u t p s y c h o l o g i c a l l y t h e p e r c e p t i o n o f one t y p e o f s e n s o r y i n -f o r m a t i o n is likely t o p a r t l y s h a p e e x p e c t a t i o n s -f o r t h e o t h e r m o d a l i t i e s ( e . g . , D a g m a n e t a l . , 2 0 T O ; Schifferstein & C l e i r e n , 2 0 0 4 ) . For i n s t a n c e , s e e i n g a large o b j e c t is likely t o lead t o t h e a n t i c i p a t i o n of p e r c e i v i n g a heavy o b j e c t w h e n y o u t r y

t o pick it u p , a n d l o w - p i t c h e d s o u n d s w h e n y o u p u t it d o w n . H e n c e , d i f f e r e n t t y p e s o f s e n s o r y s t i m u l a t i o n seem t o g o t o -g e t h e r f o r e v e r y d a y p r o d u c t s , a n d p e o p l e t e n d t o a-gree on s u c h c r o s s - m o d a l c o r r e s p o n d e n c e s ( e . g . , Schifferstein & Tan-u d j a j a , 2 0 0 4 ) . Schifferstein e t a l . , ( 2 0 1 0 ) i n v e s t i g a t e d w h e t h e r a n d h o w t h e o v e r a l l p l e a s a n t n e s s o f a m u l t i s e n s o r y p r o d u c t relates t o t h e p l e a s a n t n e s s o f its c o n s t i t u e n t s , c o m p r i s i n g of d i f f e r e n t sources o f s e n s o r y s t i m u l a t i o n . In t h i s s t u d y , s i x t e e n d i f f e r -e n t p r o d u c t v a r i a n t s ( -e . g . , a t a b l -e l a m p ) w -e r -e -e v a l u a t -e d af-t e r c r e a af-t i n g a l l p o s s i b l e c o m b i n a af-t i o n s o f e i af-t h e r a p l e a s a n af-t or u n p l e a s a n t c o l o r ( v i s i o n ) , w e i g h t d i s t r i b u t i o n ( t o u c h ) , s o u n d a n d s m e l l . Schifferstein e t a l . f o u n d t h a t t h e p l e a s a n t n e s s o f u n i s e n s o r y s t i m u l i i n f l u e n c e d t h e p l e a s a n t n e s s o f a c o m p l e x m u l t i s e n s o r y p r o d u c t o n l y t o a v e r y s m a l l d e g r e e . However, in t h i s p a r t i c u l a r s t u d y t h e s e l e c t i o n o f ( u n ) p l e a s a n t s t i m u l i f o r t h e d i f f e r e n t s e n s o r y m o d a l i t i e s w a s c a r r i e d o u t i n d e p e n d e n t l y f o r each m o d a l i t y , w h i c h may have led t o ( i n ) c o n g r u -ous s t i m u l u s c o m b i n a t i o n s . T h e r e f o r e , in t h e p r e s e n t s t u d y t h e ( u n ) p l e a s a n t s t i m u l u s s o u n d s are a l l g e n e r a t e d s p e c i f i -c a l l y f o r a p a r t i -c u l a r p r o d u -c t -c o n t e x t . This p a p e r s t u d i e s t h e e f f e c t o f ( u n ) p l e a s a n t s o u n d o n t h e p e r c e i v e d p l e a s a n t n e s s o f p r o d u c t s . W e a i m t o u n d e r s t a n d t h e d i f f e r e n c e s b e t w e e n v i s u a l a n d o v e r a l l p l e a s a n t n e s s j u d g m e n t s i n v o l v e d in p r o d u c t e x p e r i e n c e , a n d t h e k i n d o f e f f e c t s o u n d has o n t h e s e j u d g m e n t s . The e x p e r i m e n t m e a s u r e d t w o d e p e n d e n t v a r i a b l e s ( v i s u a l a n d o v e r a l l p l e a s a n t ness o f t h e p r o d u c t ) , w h i l e one f a c t o r ( a u d i t o r y p l e a s a n t -ness) w a s v a r i e d , w i t h f o u r levels o f t r e a t m e n t ( n o - s o u n d ( c o n t r o l c o n d i t i o n ) , o r i g i n a l s o u n d , p l e a s a n t s o u n d , a n d u n -p l e a s a n t s o u n d ) .

METHOD

Participants

s i x t y p a r t i c i p a n t s (34 f e m a l e a n d 26 m a l e ) , s t u d e n t s a n d e m -ployees of i n d u s t r i a l d e s i g n e n g i n e e r i n g a t Delft U n i v e r s i t y o f Technology, p a r t i c i p a t e d . The m e a n age w a s 29.7 y e a r s . Fif-t e e n p a r Fif-t i c i p a n Fif-t s w e r e r a n d o m l y assigned Fif-t o each of Fif-t h e f o u r e x p e r i m e n t a l c o n d i t i o n s d i f f e r i n g in s o u n d t y p e . A l l p a r t i c i -p a n t s r e -p o r t e d n o r m a l h e a r i n g .

Stimuli

In t o t a l e i g h t p r o d u c t s t h a t are c o m m o n l y used o n a d a i l y basis w e r e c h o s e n f o r t h e e x p e r i m e n t : d u s t b u s t e r , e p i l a t o r , hairdryer, m i c r o w a v e , mixer, shaver, t o o t h b r u s h , a n d w a s h i n g m a c h i n e . P r o d u c t s w e r e s e l e c t e d t o be n e i t h e r v e r y p l e a s a n t n o r very u n p l e a s a n t as r e g a r d s t h e i r v i s u a l q u a l i t y , as c o n -f i r m e d by 25 j u d g e s . The l o w e s t r a t i n g o n a 7 - p o i n t scale w a s f o r t h e h a i r d r y e r (3.72) a n d t h e h i g h e s t r a t i n g w a s f o r t h e mix-er ( 5 . 0 8 ) . The m e a n r a t i n g f o r a l l p r o d u c t s w a s 4 . 3 4 .

Figure 1. Examples of two product photos used in the study. Dustbuster on the left and epilator on the right. (Philips my shop Nederland have autho-rized the use of the Philips product photos for our study.)

Visual stimuli

P r o d u c t s w e r e p r e s e n t e d as p h o t o s ( s o o x 5 0 0 p i x e l s , 150 d p i ) o n a c o m p u t e r s c r e e n . A l l p r o d u c t s w e r e c h o s e n t o have a n e u t r a l c o l o r a n d w e r e p r e s e n t e d o n a w h i t e b a c k g r o u n d . Brand i n f o r m a t i o n w a s e r a s e d . See Figure i f o r t w o e x a m p l e s ( d u s t b u s t e r a n d e p i l a t o r ) .

Auditory stimuli

Each p r o d u c t w a s r e p r e s e n t e d by one c o r r e s p o n d i n g p r o d u c t s o u n d , e x c e p t f o r t h e w a s h i n g m a c h i n e , w h i c h w a s r e p -r e s e n t e d by t w o d i f f e -r e n t s o u n d s -r e s u l t i n g f -r o m d i f f e -r e n t o p e r a t i o n cycles ( i . e . , t h e w a s h i n g c y c l e a n d t h e s p i n c y c l e ) . H e n c e , in t o t a l nine o r i g i n a l p r o d u c t s o u n d s w e r e used t h a t each l a s t e d t h r e e s e c o n d s . These s o u n d s w e r e r e c o r d i n g s o f t h e m a i n f u n c t i o n i n g m e c h a n i s m s o f t h e p r o d u c t s . i::<;i 8 0 £ S fiO o a' 2 0 CI 10 15 ™ \ rpiiJlIn, i n If. f f«|rjoncy (Utirk)

Figure 2. The pleasantness manipulations of sounds presented as barkscales for two products (Dustbuster and Epilator). The full black line indicates the original sounds, the fine dashed line indicates pleasant sounds, and the course dashed line indicates unpleasant sounds.

The pleasantness of t h e o r i g i n a l p r o d u c t s o u n d s w a s m a n i p u l a t e d in Sound Studio t h r e e , f o r t h r e e o f t h e f o u r e x p e r i m e n -t a l c o n d i -t i o n s ( e x c l u d i n g -t h e n o - s o u n d c o n d i -t i o n ) : o r i g i n a l s o u n d , p l e a s a n t s o u n d a n d u n p l e a s a n t s o u n d . In t o t a l 27 sounds w e r e used (nine p r o d u c t s x t h r e e pleasantness lev-e l s ) . A c c o r d i n g t o Z w i c k lev-e r & Fasti ( 2 0 0 1 ) , t h lev-e p l lev-e a s a n t n lev-e s s o f a s o u n d is highly c o r r e l a t e d w i t h p s y c h o a c o u s t i c a l p a r a m -e t -e r s : t h -e high-er t h -e p -e r c -e i v -e d s h a r p n -e s s o r loudn-ess is, t h -e l o w e r t h e sensory pleasantness is. To make t h e s o u n d s pleasa n t , pleasa l o w p pleasa s s f i l t e r w pleasa s used pleasa n d t h e pleasa m p l i t u d e o f t h e l o w -er f r e q u e n c y range of t h e s o u n d s w a s s l i g h t l y i n c r e a s e d . To make t h e s o u n d s u n p l e a s a n t , a h i g h - p a s s f i l t e r was used a n d t h e a m p l i t u d e o f t h e h i g h e r f r e q u e n c y range was s l i g h t l y i n creased (see Figure 2 f o r t w o e x a m p l e s ) . D u r i n g t h e s e m a n i p -u l a t i o n s , t h e s p e c t r a l - t e m p o r a l c o m p o s i t i o n o f a s o -u n d w a s k e p t as close as possible t o t h e o r i g i n a l version of t h e s o u n d s . The p l e a s a n t n e s s o f t h e m a n i p u l a t e d a n d o r i g i n a l s o u n d s w a s t e s t e d in a p a i r e d - c o m p a r i s o n t a s k by asking 25 j u d g e s w h i c h s o u n d t h e y t h o u g h t w a s t h e m o s t p l e a s a n t . A p a r t i c i -p a n t c o m -p a r e d t h r e e s o u n d -p a i r s f o r each -p r o d u c t t y -p e in t w o p r e s e n t a t i o n o r d e r s . D e s c r i p t i v e s t a t i s t i c s s h o w t h a t t h e p l e a s a n t s o u n d s w e r e c h o s e n in 5 3 % o f t h e cases (n = 1350) as m o s t p l e a s a n t , o r i g i n a l s o u n d s in 3 3 % , and u n p l e a s a n t s o u n d s in 14 % o f t h e c a s e s . A r e p e a t e d measures analysis i n d i c a t e d t h a t t h e n u m b e r o f c h o i c e s f o r p l e a s a n t , o r i g i n a l , a n d u n p l e a s a n t s o u n d s w a s s i g n i f i c a n t l y d i f f e r e n t f r o m e a c h o t h e r [ F ( 2 , 4 4 8 ) = 152.68, p < . 0 0 1 ] . These d a t a c o n f i r m t h a t p l e a s a n t versions o f t h e s o u n d s w e r e p e r c e i v e d as m o r e p l e a s a n t t h a n t h e o r i g i n a l v e r s i o n s , a n d t h a t o r i g i n a l v e r s i o n s w e r e p e r c e i v e d as m o r e p l e a s a n t t h a n t h e u n p l e a s a n t v e r -sions. These p r e f e r e n c e o r d e r s w e r e c o n f i r m e d at t h e level o f t h e i n d i v i d u a l p r o d u c t s . However, t h e m a n i p u l a t i o n s of t h e h a i r d r y e r s o u n d s d i d n o t y i e l d t h e p r e d i c t e d p r e f e r e n c e o r der. Pleasant s o u n d s in a l l h a i r d r y e r c o m b i n a t i o n s w e r e c h o -sen in 3 4 % o f t h e cases ( n = 150) as m o s t p l e a s a n t , o r i g i n a l s o u n d s in 2 2 % , a n d u n p l e a s a n t s o u n d s in 4 4 % o f t h e cases. T h e r e f o r e , f o r t h e h a i r d r y e r t h e u n p l e a s a n t version o f t h e s o u n d s w a s used as t h e p l e a s a n t s o u n d c o n d i t i o n , t h e pleasa n t version o f t h e s o u n d s w pleasa s used pleasas t h e o r i g i n pleasa l s o u n d c o n -d i t i o n , a n -d t h e o r i g i n a l v e r s i o n o f t h e s o u n -d w a s use-d as t h e u n p l e a s a n t s o u n d c o n d i t i o n in s u b s e q u e n t analyses.

Procedure

A p a r t i c i p a n t w a s r a n d o m l y assigned t o any of t h e f o u r e x p e r i m e n t a l c o n d i t i o n s : c o n t r o l c o n d i t i o n , o r i g i n a l s o u n d c o n d i t i o n , pleasant s o u n d c o n d i t i o n , a n d u n p l e a s a n t s o u n d c o n d i -t i o n . The visual a n d a u d i -t o r y s -t i m u l i w e r e presen-ted using a specially designed a p p l i c a t i o n d e v e l o p e d using t h e T r o l l t e c h Qt (Mac OS X — free e d i t i o n ) t o o l kit. The a p p l i c a t i o n ran o n a Macintosh iMac I n t e l Core 2 Duo w i t h 19" s c r e e n . For t h e p r e s e n t a t i o n o f t h e a u d i t o r y s t i m u l i , e x t e r n a l h e a d p h o n e s (Sennheiser HD 2 0 5 ) w e r e u s e d . P a r t i c i p a n t s w e r e seated in f r o n t of t h e screen a t a d i s t a n c e o f a p p r o x i m a t e l y 5 0 c m . They w e r e i n s t r u c t e d t o rate t h e p r o d u c t s p r e s e n t e d as p h o t o s o n t h e c o m p u t e r screen on t h e bases o f t h e i r visual a n d overall pleasantness. In a l l c o n d i t i o n s , p r o d u c t t y p e s w e r e r a n d o m l y p r e s e n t e d f o r each p a r t i c i p a n t . The e n t i r e e x p e r i m e n t w a s

s e l f - p a c e d and t h e r e w e r e no pauses b e t w e e n t h e r a t i n g t r i a l s . One r a t i n g session for nine p r o d u c t s lasted a b o u t five m i n u t e s . In t h e t h r e e e x p e r i m e n t a l c o n d i t i o n s ( o r i g i n a l , p l e a s a n t , u n -p l e a s a n t ) , t w o r a t i n g scales (visual -p l e a s a n t n e s s a n d o v e r a l l pleasantness) a p p e a r e d s i m u l t a n e o u s l y on t h e s c r e e n , b u t w e r e i n i t i a l l y inactive f o r r a t i n g . The p a r t i c i p a n t w a s asl<ed t o listen t o t h e s o u n d o f t h e p r o d u c t p r e s e n t e d o n t h e s c r e e n . A p a r t i c i p a n t w a s a l l o w e d t o listen t o t h e s o u n d m o r e t h a n once w h i l e e v a l u a t i n g t h e p l e a s a n t n e s s . A l l s o u n d s w e r e p r e s e n t e d at a similar, c o m f o r t a b l e l i s t e n i n g level p r e s e r v i n g t h e n a t u r a l v a r i a t i o n in t h e loudness of s o u n d s . P a r t i c i p a n t s w e r e n o t a l -l o w e d t o change t h e s o u n d -leve-ls d u r i n g t h e e x p e r i m e n t . A f t e r a s o u n d w a s h e a r d , t h e r a t i n g scales b e c a m e a c t i v e . P a r t i c i p a n t s f i r s t rated t h e v i s u a l p l e a s a n t n e s s a n d t h e n rated t h e o v e r a l l p l e a s a n t n e s s o f t h e p r o d u c t u n d e r t h e i n f l u ence o f t h e s o u n d . They w e r e i n s t r u c t e d t h a t v i s u a l p l e a s a n t -ness w a s a b o u t a s e n s o r y j u d g m e n t based o n l y o n t h e v i s u a l q u a l i t y o f t h e p r o d u c t . For t h e o v e r a l l p l e a s a n t n e s s r a t i n g , a p a r t i c i p a n t w a s e n c o u r a g e d t o i m a g i n e t h e p r o d u c t as a w h o l e w i t h a l l sensory p r o p e r t i e s . Ratings w e r e c o l l e c t e d o n a s e v e n - p o i n t Lil<ert scale (one i n d i c a t i n g ' n o t p l e a s a n t ' a n d seven i n d i c a t i n g ' v e r y p l e a s a n t ' ) . In t h e c o n t r o l c o n d i t i o n , t h e nine r a t i n g t r i a l s w e r e c o m p l e t e d in t h e a b s e n c e o f a c o r r e -s p o n d i n g p r o d u c t -s o u n d .

Dofa analysis

We analyzed t h e p l e a s a n t n e s s responses in SPSS by d o u b l y m u l t i v a r i a t e r e p e a t e d m e a s u r e s analysis o f v a r i a n c e (Ste-v e n s , 2 0 0 2 , p.538). In t h i s analysis, w e used t h e o (Ste-v e r a l l a n d v i s u a l p l e a s a n t n e s s r a t i n g s as t h e t w o d e p e n d e n t v a r i a b l e s , w h i l e P r o d u c t w a s a w i t h i n - p a r t i c i p a n t s v a r i a b l e w i t h nine levels, a n d C o n d i t i o n d i f f e r e d b e t w e e n p a r t i c i p a n t s w i t h f o u r levels ( c o n t r o l , o r i g i n a l , p l e a s a n t , u n p l e a s a n t s o u n d ) . For t h e m u l t i v a r i a t e e f f e c t s , w e r e p o r t t h e v a l u e s o f Rao's F, c o r r e -s p o n d i n g t o Will<-s'-s • . Significant effect-s w e r e i n v e -s t i g a t e d in m o r e d e t a i l by r e p e a t e d m e a s u r e s analyses f o r t h e s e p a r a t e d e p e n d e n t v a r i a b l e s . In a c c o r d a n c e w i t h Stevens ( 2 0 0 2 ) , w e c o r r e c t e d t h e degrees o f f r e e d o m o f t h e u n i v a r i a t e t e s t s w i t h t h e G r e e n h o u s e G e i s e r • if • < 0.7, a n d w e averaged t h e • v a l -ues f r o m G r e e n h o u s e - G e i s e r a n d H u y n h - F e l d t , w h e n • > 0.7. Differences b e t w e e n i n d i v i d u a l s a m p l e s w e r e i n v e s t i g a t e d by p o s t hoc t - t e s t s w i t h B o n f e r r o n i a d j u s t m e n t .

RESULTS

In t h e m u l t i v a r i a t e t e s t s , w e f o u n d s i g n i f i c a n t e f f e c t s f o r C o n -d i t i o n (p < o . o o i ) . P r o -d u c t (p < 0 . 0 0 1 ) , a n -d t h e C o n -d i t i o n x P r o d u c t i n t e r a c t i o n (p = 0 . 0 2 4 ) . However, in t h e u n i v a r i a t e s i g n i f i c a n c e t e s t s in t h e s e p a r a t e analyses f o r t h e t w o t y p e s o f p l e a s a n t n e s s j u d g m e n t s , t h e C o n d i t i o n x P r o d u c t i n t e r a c -t i o n d i d no l o n g e r reach significance ( o v e r a l l p l e a s a n -t n e s s p > 0 . 2 0 ; v i s u a l p l e a s a n t n e s s p = 0 . 0 6 ) . As w e w e r e n o t p r i -m a r i l y i n t e r e s t e d in t h e d a t a f o r t h e i n d i v i d u a l p r o d u c t s , w e d e c i d e d t o p e r f o r m no a d d i t i o n a l analyses a t t h e level o f t h e i n d i v i d u a l p r o d u c t s .

If j u d g m e n t s for visual pleasantness are unaffected by t h e sounds p a r t i c i p a n t s hear, w e expect responses in the f o u r c o n -d i t i o n s t o be i -d e n t i c a l . However, t h e C o n -d i t i o n main was sta-tistically significant [F (3,56) = 3.1, p < 0 . 0 5 ] . Post-hoc tests w i t h Bonferroni a d j u s t m e n t indicate t h a t these o u t c o m e s are mainly due t o a difference b e t w e e n t h e c o n t r o l c o n d i t i o n and t h e pleasant c o n d i t i o n (p < 0 . 0 5 ) . A separate analysis c o m p a r -ing only t h e t h r e e e x p e r i m e n t a l c o n d i t i o n s shows no Condition main effect [F(2,42) = i . 6 , p > 0 . 2 0 ] .

We expect t h e overall pleasantness j u d g m e n t s t o be affected by t h e p r o d u c t sounds, and t h i s is c o n f i r m e d by a Condition main effect [F(3,56) = 4 . 9 , p < o . o i ] . Post-hoc tests s h o w dif-ferences between the c o n t r o l c o n d i t i o n on t h e one hand and the o r i g i n a l and t h e u n p l e a s a n t c o n d i t i o n s on t h e o t h e r hand (p < o . o i and p < 0 . 0 5 , respectively). A l t h o u g h no o t h e r significant differences are f o u n d , t h e separate analysis c o m p a r -ing t h e t h r e e e x p e r i m e n t a l c o n d i t i o n s s t i l l shows a Condition main effect [F(2,42) = 3.2, p < 0 . 0 5 ] . Post hoc analyses s h o w no significant differences b e t w e e n t h e t h r e e c o n d i t i o n s , a l t h o u g h difference b e t w e e n t h e o r i g i n a l and t h e pleasant c o n d i t i o n j u s t failed t o reach significance (p = 0 . 0 5 5 ) .

These analyses show t h a t t h e pleasantness j u d g m e n t s in t h e c o n t r o l c o n d i t i o n , w h e r e a p r o d u c t is presented w i t h o u t any s o u n d , differ s u b s t a n t i a l l y f r o m those in t h e t h r e e e x p e r i m e n -t a l c o n d i -t i o n s . This sugges-ts -t h a -t -t h e presence or absence of sounds has an i m p o r t a n t effect on h o w j u d g m e n t s of b o t h v i -sual and overall pleasantness are f o r m e d . In t h e absence of s o u n d , p a r t i c i p a n t s seem t o t r e a t t h e v i s u a l and overall pleas-antness j u d g m e n t s s i m i l a r l y : The mean ratings are very similar (3.89 f o r visual, 4 . 0 2 f o r overall pleasantness) and the Pearson c o r r e l a t i o n coefficient b e t w e e n t h e visual and overall pleasant-ness ratings is 0.32 [N = 135, p < 0 . 0 0 1 ] .

In c o n t r a s t , in t h e t h r e e sound c o n d i t i o n s t h e means for visual pleasantness are c o n s i s t e n t l y higher t h a n t h e means for overall pleasantness. Surprisingly, a l t h o u g h t h e differences b e t w e e n the t h r e e e x p e r i m e n t a l c o n d i t i o n s fail t o reach s t a t i s t i c a l signif-icance, t h e p a t t e r n of means is s i m i l a r f o r the visual and overall pleasantness j u d g m e n t s , w i t h t h e means consistently d i f f e r i n g a b o u t one unit (Figure 3 ) . The Pearson c o r r e l a t i o n coefficients b e t w e e n visual and overall pleasantness ratings for these t h r e e c o n d i t i o n s vary b e t w e e n 0.24 and 0.27 (N = 135. P < 0.01).

I ! ,

NoSoLnd Ofiginal PJea£inl Unj^easanl

Condltkm

Figure 3. Visual and overall pleasantness ratings (± SEM) in the four experi-mental conditions.

DISCUSSION

The present s t u d y s h o w s t h a t r a t i n g s f o r v i s u a l a n d o v e r a l l p l e a s a n t n e s s are s i m i l a r w h e n no s o u n d s are p r o v i d e d w i t h t h e visual s t i m u l i ( p i c t u r e s ) . This is n o t s u r p r i s i n g , since par-t i c i p a n par-t s are nopar-t p r o v i d e d w i par-t h any n o n - v i s u a l i n f o r m a par-t i o n . H e n c e , w h e n t h e y j u d g e o v e r a l l p l e a s a n t n e s s , t h e y can o n l y base t h e i r j u d g m e n t s o n t h e v i s u a l i n f o r m a t i o n p r o v i d e d . T h e r e f o r e , t h e j u d g m e n t s o f v i s u a l p l e a s a n t n e s s are likely t o c o n c u r w i t h t h o s e o f o v e r a l l p l e a s a n t n e s s in t h i s c o m p a r i s o n . W h e n p a r t i c i p a n t s are p r o v i d e d w i t h p r o d u c t s o u n d s , h o w -ever, t h e o v e r a l l p l e a s a n t n e s s d a t a s h o w s a c o n s i d e r a b l e d e c r e a s e in pleasantness r a t i n g s . This d e c r e a s e may be d u e t o t h e l o w a p p r e c i a t i o n t h a t is g e n e r a l l y f o u n d f o r p r o d u c t s o u n d s . In c o n t r a s t , v i s u a l p l e a s a n t n e s s i n c r e a s e d w h e n s o u n d w a s a d d e d . Possibly, t h e p l e a s a n t n e s s o f t h e p i c t u r e s c o n t r a s t e d w i t h t h e l o w a u d i t o r y p l e a s a n t n e s s o f t h e s o u n d s , a n d t h e r e b y b o o s t e d t h e v i s u a l p l e a s a n t n e s s ratings in t h e s t u d y ( A n d e r s o n , 1973)- A l t e r n a t i v e l y , w e m i g h t suggest t h a t t h e a d d i t i o n o f s o u n d m a k e s t h e p r o d u c t c o m e alive, w h i c h m a k e s t h e v i s u a l r e p r e s e n t a t i o n m o r e i n t e r e s t i n g a n d i n -creases its p l e a s a n t n e s s . The f i n d i n g t h a t t h e p r e s e n t a t i o n o f p r o d u c t s o u n d s a f f e c t s b o t h o v e r a l l a n d v i s u a l p l e a s a n t n e s s r a t i n g s has i m p l i c a t i o n s f o r p r o d u c t d e v e l o p m e n t p r a c t i c e , because it i n d i c a t e s t h a t c o m p a n y d e c i s i o n s s h o u l d n o t be b a s e d on t h e e v a l u a t i o n o f p a r t i a l d a t a . If p a r t i c i p a n t s in c o n s u m e r panels are p r o v i d e d w i t h l i m i t e d i n f o r m a t i o n , t h e i r j u d g m e n t s w i l l o n l y have l i m i t e d e x t e r n a l v a l i d i t y . As w e see in t h e p r e s e n t s t u d y , p r o v i d -i n g a d d -i t -i o n a l sensory ( a u d -i t o r y ) -i n f o r m a t -i o n has a s -i g n -i f -i c a n t i m p a c t on b o t h t y p e s o f p l e a s a n t n e s s j u d g m e n t s .

Similarly, sensory processes are l i k e l y t o a f f e c t c o n s u m e r s ' b u y i n g processes (Lageat e t a l . , 2 0 0 3 ; Spence & G a l l a c e , 2 o n ) . Consumers o f t e n p u r c h a s e h o u s e h o l d a p p l i a n c e s in s t o r e s in t h e absence o f s o u n d . This is even m o r e so f o r o n -line s h o p p i n g e x p e r i e n c e s . In m a n y cases, p e o p l e w h o b u y p r o d u c t s are a b l e t o use only a single s e n s o r y m o d a l i t y ( i . e . , v i s i o n ) t o c o m p a r e p r o d u c t s (see Fenko e t a l . , 2 0 0 9 ) . Thus, t h e i r pleasantness j u d g m e n t s are m a i n l y b a s e d on p r o d u c t a p p e a r a n c e , w h i c h may p r o v i d e d i f f e r e n t i n f o r m a t i o n t h a n t h e a u d i t o r y p r o d u c t p r o p e r t i e s . M u l t i - s e n s o r y experiences o n l y t a k e place in h o m e e n v i r o n m e n t s a f t e r p r o d u c t p u r c h a s e , a n d people's j u d g m e n t s o f p r o d u c t p l e a s a n t n e s s may need t o be a d j u s t e d a c c o r d i n g l y . As a c o n s e q u e n c e , m a n y buyers may be d i s a p p o i n t e d w i t h t h e i r p u r c h a s e , because even t h e p r o p e r t i e s o f t h e r e l a t i v e l y p l e a s a n t s o u n d s may lead t o a d e -crease in o v e r a l l p r o d u c t e v a l u a t i o n . Moreover, retailers a n d p r o d u c e r s may be c o n f r o n t e d w i t h c o n s u m e r c o m p l a i n t s , as t h e p r o d u c t may n o t live u p t o c o n s u m e r e x p e c t a t i o n s . The pleasantness r a t i n g s in Figure 3 suggest t h a t t h e o r i g i -n a l p r o d u c t s o u -n d s a -n d t h e u -n p l e a s a -n t v e r s i o -n s we c r e a t e d w e r e a b o u t e q u a l l y u n p l e a s a n t . This i n d i c a t e s t h a t t h e s o u n d q u a l i t y o f t h e p r o d u c t s c u r r e n t l y f o u n d in t h e m a r k e t does n o t e n a b l e p l e a s a n t a u d i t o r y e x p e r i e n c e s . The s o u n d s w e used b e l o n g t o everyday p r o d u c t s t h a t p e o p l e use f o r m u n d a n e t a s k s such as s h a v i n g , d r y i n g hair, c o o k i n g , w a s h i n g , a n d so

o n . These u n p l e a s a n t s o u n d s may lead t o m o m e n t a r y a n n o y -ance ( e . g . , p r e p a r i n g a cake w i t h a l o u d mixer can d i s t u r b t h e user a n d o t h e r p e o p l e ) , t h e desire t o a v o i d using t h e p r o d -u c t again ( e . g . , a n e l e c t r i c t o o t h b r -u s h p r o d -u c i n g l o -u d a n d rough s o u n d s d o e s n o t invite t h e i m p r o v e m e n t o f p e r s o n a l h y g i e n e ) , o r even h e a l t h p r o b l e m s d u e t o sensory f a t i g u e ( e . g . , b e i n g e x p o s e d t o a l o u d hissing s o u n d f r o m an a i r c o n -d i t i o n e r may e v e n t u a l l y lea-d t o h e a l t h issues). On t h e p o s i t i v e s i d e , o u r results s u g g e s t t h a t i f efforts are p u t i n t o i m p r o v i n g t h e s o u n d q u a l i t y , b o t h t h e v i s u a l and t h e o v e r a l l e x p e r i e n c e s w i t h p r o d u c t s are e n h a n c e d a n d , c o n s e q u e n t l y , users w i l l be m o r e p l e a s e d a n d w i l l i n g t o i n t e r a c t w i t h t h e p r o d u c t s . F u r t h e r m o r e , even t h o u g h i n t r i n s i c s o u n d p r o p e r t i e s f o r p r o d u c t s may g e n e r a l l y be e v a l u a t e d as u n p l e a s a n t , s o m e c o g n i t i v e a s s o c i a t i o n s may n o n e t h e l e s s be p o s i t i v e a n d i m -prove p r o d u c t p u r c h a s e (Özcan, 2014). For i n s t a n c e , a roar-ing m o t o r s o u n d m a y evoke associations w i t h b e i n g w i l d a n d u n t a m a b l e , a n d may make t h e user f e e l a d v e n t u r o u s in t h e c o n t e x t o f a m o t o r b i k e r i d e . For a user w h o likes t o f e e l a d -v e n t u r o u s , u s i n g t h i s p r o d u c t may gi-ve h i m m o r e p l e a s u r e , in w h i c h case t h i s s o u n d may i m p r o v e his p r o d u c t e v a l u a t i o n . H e n c e , m a k i n g use o f expressive sound p r o p e r t i e s m a y p r o v i d e an a d d i t i o n a l r o u t e f o r i m p r o v e m e n t in t h e p r o d u c t d e -sign ( e . g . , L u d d e n & S c h i f f e r s t e i n , 2 0 0 7 ) .

We have s h o w n t h a t t h e r e is i n t e r p l a y b e t w e e n t h e s e n s o r y p r o p e r t i e s o f a p r o d u c t (audiovisual) w i t h regard t o t h e e x p e -rience of p l e a s a n t n e s s . However, our m a n i p u l a t i o n s w e r e re-s t r i c t e d t o t h e a u d i t o r y p r o d u c t p r o p e r t i e re-s only a n d w e have n o t m a n i p u l a t e d t h e c o n t r i b u t i o n of v i s u a l p r o d u c t p r o p e r -t i e s . A f u -t u r e s -t u d y c o u l d s y s -t e m a -t i c a l l y inves-tiga-te h o w each s e n s o r y p r o p e r t y o f a p r o d u c t (e.g., visual a n d a u d i t o r y ) i n d i -v i d u a l l y c o n t r i b u t e s t o affecti-ve p r o d u c t e x p e r i e n c e s . One o f t h e l i m i t a t i o n s o f t h e c u r r e n t s t u d y is t h e p a r t i c i p a n t s ' lack o f p h y s i c a l e x p e r i e n c e w i t h t h e p r o d u c t p r o p e r -t i e s -t e s -t e d ( i . e . , a u d i -t o r y a n d v i s u a l p r o d u c -t p r o p e r -t i e s ) . In o t h e r w o r d s , p a r t i c i p a n t s ' j u d g m e n t s o n v i s u a l a n d o v e r a l l p l e a s a n t n e s s are b a s e d o n t h e p h o t o s a n d r e c o r d e d s o u n d s o f p r o d u c t s i n s t e a d o f t h e p r o d u c t s p r o p e r ( i . e . , t a n g i b l e o r p h y s i c a l p r o d u c t s ) . A f u t u r e s t u d y c o u l d i n v e s t i g a t e w h e t h e r t h e e f f e c t s f o u n d w o u l d p e r s i s t if p a r t i c i p a n t s i n t e r a c t e d w i t h p h y s i c a l p r o d u c t s ( p r o v i d e d t h a t t h e p h y s i c a l p r o d u c t s can be m o d i f i e d in s i t u in o r d e r t o p r o d u c e p l e a s a n t as w e l l as u n p l e a s a n t s o u n d s ) . F u r t h e r m o r e , o t h e r p r o d u c t e x p e r i e n c es p e r t a i n i n g t o basic a f f e c t i v e responses c o u l d also be m e a -s u r e d a-s a c o n t i n u a t i o n o f t h e c u r r e n t -s t u d y . For e x a m p l e , it c o u l d be t e s t e d w h e t h e r t h e p r o d u c t is p e r c e i v e d as p l e a s -i n g , s t -i m u l a t -i n g o r p o w e r f u l -in r e l a t -i o n t o t h e -i n t e r v e n t -i o n s c a u s e d by t h e s o u n d s o f t h e p r o d u c t s , p e r h a p s even w i t h dif-f e r e n t d e g r e e s o dif-f p l e a s a n t n e s s .

ACKNOWLEDGEMENTS

S h a r m i s t h a Banerjee t o o k p a r t in t h e study as p a r t o f an e l e c t i v e course on research d e s i g n . She was involved in t h e p r e p a r a t i o n of t h e e x p e r i m e n t a l m a t e r i a l a n d c o n d u c t i n g t h e e x p e r i m e n t s .

The a u t h o r s w o u l d like t o t h a n k S h a r m i s t h a f o r her v a l u a b l e c o n t r i b u t i o n . In a d d i t i o n , c o n s u m e r b r a n d Philips have been h e l p f u l in p r o v i d i n g t h e p r o d u c t images f o r o u r study.

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